通常情况下使用
mybatis的时候我们会添加一个mybatis-config.xml的文件. 这个文件是如何解析的呢?
- 先编辑一个
mybatis-config.xml文件放在src\resources目录下,具体内容如下
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<setting name="lazyLoadingEnabled" value="true"/>
</settings>
<typeAliases>
<!-- <package name="com.huifer.mybatis.entity"/>-->
<typeAlias type="com.huifer.mybatis.entity.Person" alias="Person"/>
</typeAliases>
<!-- 定义数据库的信息，默认使用development数据库构建环境 -->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!-- 定义映射器 -->
<mappers>
<mapper resource="com/huifer/mybatis/mapper/PersonMapper.xml"/>
</mappers>
</configuration>
- 目前已知的条件: 这是一个配置文件,应该有一个对应的JAVA类来存储
org.apache.ibatis.session.Configuration
<settings>
<setting name="lazyLoadingEnabled" value="true"/>
</settings>看上述的xml文件标签内容是否在org.apache.ibatis.session.Configuration存在,搜索lazyLoadingEnabled属性
protected boolean lazyLoadingEnabled = false;-
其他的一些属性应该也会有对应的比如查询超时
defaultStatementTimeout等等. -
mappers 标签的属性对应
protected final Map<String, MappedStatement> mappedStatements = new StrictMap<MappedStatement>("Mapped Statements collection")
.conflictMessageProducer((savedValue, targetValue) ->
". please check " + savedValue.getResource() + " and " + targetValue.getResource());
protected final Map<String, Cache> caches = new StrictMap<>("Caches collection");
protected final Map<String, ResultMap> resultMaps = new StrictMap<>("Result Maps collection");
protected final Map<String, ParameterMap> parameterMaps = new StrictMap<>("Parameter Maps collection");
protected final Map<String, KeyGenerator> keyGenerators = new StrictMap<>("Key Generators collection");- 打开
mybatis提供的测试类org.apache.ibatis.submitted.global_variables_defaults.ConfigurationTest查看方法org.apache.ibatis.submitted.global_variables_defaults.ConfigurationTest.applyDefaultValueOnXmlConfiguration
@Test
void applyDefaultValueOnXmlConfiguration() throws IOException {
Properties props = new Properties();
props.setProperty(PropertyParser.KEY_ENABLE_DEFAULT_VALUE, "true");
Reader reader = Resources.getResourceAsReader("org/apache/ibatis/submitted/global_variables_defaults/mybatis-config.xml");
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader, props);
Configuration configuration = factory.getConfiguration();
Assertions.assertThat(configuration.getJdbcTypeForNull()).isEqualTo(JdbcType.NULL);
Assertions.assertThat(((UnpooledDataSource) configuration.getEnvironment().getDataSource()).getUrl())
.isEqualTo("jdbc:hsqldb:mem:global_variables_defaults");
Assertions.assertThat(configuration.getDatabaseId()).isEqualTo("hsql");
Assertions.assertThat(((SupportClasses.CustomObjectFactory) configuration.getObjectFactory()).getProperties().getProperty("name"))
.isEqualTo("default");
}- 不难发现
org.apache.ibatis.session.SqlSessionFactoryBuilder.build(java.io.Reader, java.util.Properties)通过这个方法就可以将mybatis-config.xml文件解析出来了
public SqlSessionFactory build(Reader reader, Properties properties) {
return build(reader, null, properties);
} /**
* 真正的创建方法
*
* @param reader inputStream
* @param environment
* @param properties 属性值
* @return
*/
public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
try {
// 通过 XMLConfigBuilder 解析成一个 XMLConfigBuilder
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
// 往下点进去看方法
// 1. org.apache.ibatis.session.SqlSessionFactoryBuilder.build(org.apache.ibatis.session.Configuration)
// 2. org.apache.ibatis.session.defaults.DefaultSqlSessionFactory.DefaultSqlSessionFactory
// 3. 第二步的构造方法中生成了 `org.apache.ibatis.session.Configuration`对象
return build(parser.parse());
} catch (Exception e) {
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
reader.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
} public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}public class DefaultSqlSessionFactory implements SqlSessionFactory {
private final Configuration configuration;
public DefaultSqlSessionFactory(Configuration configuration) {
this.configuration = configuration;
}
}- 调用链路
org.apache.ibatis.session.SqlSessionFactoryBuilder.build(java.io.Reader, java.util.Properties)org.apache.ibatis.builder.xml.XMLConfigBuilder.parseorg.apache.ibatis.session.SqlSessionFactoryBuilder.build(java.io.Reader, java.lang.String, java.util.Properties)org.apache.ibatis.session.SqlSessionFactoryBuilder.build(org.apache.ibatis.session.Configuration)org.apache.ibatis.session.defaults.DefaultSqlSessionFactory
public Configuration parse() {
if (parsed) {
throw new BuilderException("Each XMLConfigBuilder can only be used once.");
}
parsed = true;
parseConfiguration(parser.evalNode("/configuration"));
return configuration;
}private void parseConfiguration(XNode root) {
try {
//issue #117 read properties first
propertiesElement(root.evalNode("properties"));
Properties settings = settingsAsProperties(root.evalNode("settings"));
loadCustomVfs(settings);
loadCustomLogImpl(settings);
typeAliasesElement(root.evalNode("typeAliases"));
pluginElement(root.evalNode("plugins"));
objectFactoryElement(root.evalNode("objectFactory"));
objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
reflectorFactoryElement(root.evalNode("reflectorFactory"));
settingsElement(settings);
// read it after objectFactory and objectWrapperFactory issue #631
environmentsElement(root.evalNode("environments"));
databaseIdProviderElement(root.evalNode("databaseIdProvider"));
typeHandlerElement(root.evalNode("typeHandlers"));
mapperElement(root.evalNode("mappers"));
} catch (Exception e) {
throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
}
}- 先自己先一段测试用例
@Test
void testXmlConfigurationLoad() throws IOException {
Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);
Configuration configuration = factory.getConfiguration();
System.out.println();
}- properties 标签属性加载
private void propertiesElement(XNode context) throws Exception {
if (context != null) {
// 加载下级标签,解析属性
Properties defaults = context.getChildrenAsProperties();
String resource = context.getStringAttribute("resource");
String url = context.getStringAttribute("url");
if (resource != null && url != null) {
// 不会同时设置 resource 和 url 的属性值
throw new BuilderException("The properties element cannot specify both a URL and a resource based property file reference. Please specify one or the other.");
}
if (resource != null) {
// 覆盖子节点属性
defaults.putAll(Resources.getResourceAsProperties(resource));
} else if (url != null) {
// 覆盖子节点属性
defaults.putAll(Resources.getUrlAsProperties(url));
}
Properties vars = configuration.getVariables();
if (vars != null) {
defaults.putAll(vars);
}
parser.setVariables(defaults);
// 设置到 全局的 configuration 中
configuration.setVariables(defaults);
}
}- 解析标签属性
/**
* 解析配置文件xml的标签将返回 {name:value}
* @return
*/
public Properties getChildrenAsProperties() {
Properties properties = new Properties();
for (XNode child : getChildren()) {
String name = child.getStringAttribute("name");
String value = child.getStringAttribute("value");
if (name != null && value != null) {
properties.setProperty(name, value);
}
}
return properties;
}- 当前配置文件
<properties resource="test.properties" >
<property name="hello" value="world"/>
<property name="k" value="v"/>
</properties>
可以看到defaults就是我们配置的标签属性值了
为了测试后半段内容将test.properties添加一个属性
k=java
可以看到这段话
if (resource != null && url != null) {
// 不会同时设置 resource 和 url 的属性值
throw new BuilderException("The properties element cannot specify both a URL and a resource based property file reference. Please specify one or the other.");
}
if (resource != null) {
// 覆盖子节点属性
defaults.putAll(Resources.getResourceAsProperties(resource));
} else if (url != null) {
// 覆盖子节点属性
defaults.putAll(Resources.getUrlAsProperties(url));
}defaults.putAll()方法将会读取properties文件中的内容. 并且覆盖<properties>标签的子节点
最终设置结果k的属性值修改了:happy:
- 别名加载,配置文件在下方,在debug阶段选择开启不同的别名方式进行源码查看
<typeAliases>
<!-- <package name="com.huifer.mybatis.entity"/>-->
<typeAlias type="com.huifer.mybatis.entity.Person" alias="Person"/>
</typeAliases>private void typeAliasesElement(XNode parent) {
if (parent != null) {
for (XNode child : parent.getChildren()) {
if ("package".equals(child.getName())) {
// 解析 package 标签
String typeAliasPackage = child.getStringAttribute("name");
configuration.getTypeAliasRegistry().registerAliases(typeAliasPackage);
} else {
// 解析 typeAliases 标签
String alias = child.getStringAttribute("alias");
String type = child.getStringAttribute("type");
try {
Class<?> clazz = Resources.classForName(type);
// 别名注册
if (alias == null) {
typeAliasRegistry.registerAlias(clazz);
} else {
typeAliasRegistry.registerAlias(alias, clazz);
}
} catch (ClassNotFoundException e) {
throw new BuilderException("Error registering typeAlias for '" + alias + "'. Cause: " + e, e);
}
}
}
}
}
目前解析的内容为Person这个实体
- 别名加载方法
/**
* 别名注册,
* typeAliases 是一个map key=>别名,value=>字节码
*
* @param alias 别名名称
* @param value 别名的字节码
*/
public void registerAlias(String alias, Class<?> value) {
if (alias == null) {
throw new TypeException("The parameter alias cannot be null");
}
// issue #748
String key = alias.toLowerCase(Locale.ENGLISH);
if (typeAliases.containsKey(key) && typeAliases.get(key) != null && !typeAliases.get(key).equals(value)) {
throw new TypeException("The alias '" + alias + "' is already mapped to the value '" + typeAliases.get(key).getName() + "'.");
}
typeAliases.put(key, value);
}完成了properties标签和typeAliases看一下此时的configuration是什么
通过下面的代码我们知道properties属性放置在 configuration.variables
configuration.setVariables(defaults); public void setVariables(Properties variables) {
this.variables = variables;
}
typeAaliases放在this.configuration.typeAliasRegistry.typeAliases中
-
org.apache.ibatis.builder.xml.XMLConfigBuilder#parseConfiguration -
设置 setting 标签下的属性相关代码
Properties settings = settingsAsProperties(root.evalNode("settings")); // vfs 虚拟文件相关属性 loadCustomVfs(settings); // 日志实现类 loadCustomLogImpl(settings);
private Properties settingsAsProperties(XNode context) {
if (context == null) {
// 返回一个空的 Properties
return new Properties();
}
Properties props = context.getChildrenAsProperties();
// Check that all settings are known to the configuration class
MetaClass metaConfig = MetaClass.forClass(Configuration.class, localReflectorFactory);
for (Object key : props.keySet()) {
if (!metaConfig.hasSetter(String.valueOf(key))) {
throw new BuilderException("The setting " + key + " is not known. Make sure you spelled it correctly (case sensitive).");
}
}
return props;
}返回结果就是Properties 对象
-
修改
mybatis-config.xml<setting name="logImpl" value="LOG4J"/>
org.apache.ibatis.builder.xml.XMLConfigBuilder#loadCustomLogImpl
private void loadCustomLogImpl(Properties props) {
Class<? extends Log> logImpl = resolveClass(props.getProperty("logImpl"));
configuration.setLogImpl(logImpl);
}-
熟悉的方法他来了
/** * 通过别名查询 * @param alias * @param <T> * @return */ protected <T> Class<? extends T> resolveClass(String alias) { if (alias == null) { return null; } try { return resolveAlias(alias); } catch (Exception e) { throw new BuilderException("Error resolving class. Cause: " + e, e); } }
protected <T> Class<? extends T> resolveAlias(String alias) { return typeAliasRegistry.resolveAlias(alias); }
/** * 获取别名的value * * @param string 别名名称 * @param <T> * @return */ @SuppressWarnings("unchecked") // throws class cast exception as well if types cannot be assigned public <T> Class<T> resolveAlias(String string) { try { if (string == null) { return null; } // issue #748 String key = string.toLowerCase(Locale.ENGLISH); Class<T> value; if (typeAliases.containsKey(key)) { value = (Class<T>) typeAliases.get(key); } else { value = (Class<T>) Resources.classForName(string); } return value; } catch (ClassNotFoundException e) { throw new TypeException("Could not resolve type alias '" + string + "'. Cause: " + e, e); } }
从别名
private final Map<String, Class<?>> typeAliases = new HashMap<>();存储空间获取存储的实体直接返回
-
此时该日志为：
org.apache.ibatis.logging.log4j.Log4jImpl
-
org.apache.ibatis.builder.xml.XMLConfigBuilder#pluginElement -
准备一个插件类测试用
package com.huifer.mybatis.plugins; import org.apache.ibatis.plugin.Interceptor; import org.apache.ibatis.plugin.Invocation; import org.apache.ibatis.plugin.Plugin; import java.util.Properties; //@Intercepts({ // @Signature( // type = Executor.class, // method = "query", // args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class} // ) //}) public class TestPlugin implements Interceptor { @Override public Object intercept(Invocation invocation) throws Throwable { return invocation.proceed(); } @Override public Object plugin(Object target) { return Plugin.wrap(target, this); } @Override public void setProperties(Properties properties) { System.out.println(properties); } }
修改 mybatis-config.xml
<plugins>
<plugin interceptor="com.huifer.mybatis.plugins.TestPlugin">
<property name="testPlugins" value="tPl"/>
</plugin>
</plugins> /**
* 记载 plugins 标签内容
* @param parent
* @throws Exception
*/
private void pluginElement(XNode parent) throws Exception {
if (parent != null) {
for (XNode child : parent.getChildren()) {
// <plugin interceptor="com.huifer.mybatis.plugins.TestPlugin"> 获取 interceptor 值
String interceptor = child.getStringAttribute("interceptor");
// 获取plugin 下面的 property 标签数据
Properties properties = child.getChildrenAsProperties();
Interceptor interceptorInstance = (Interceptor) resolveClass(interceptor).getDeclaredConstructor().newInstance();
interceptorInstance.setProperties(properties);
configuration.addInterceptor(interceptorInstance);
}
}
}先看interceptor 和 properties
-
Interceptor interceptorInstance = (Interceptor) resolveClass(interceptor).getDeclaredConstructor().newInstance();这段内容其实是通过反射获取对应的实例 ， -
注意：
org.apache.ibatis.plugin.Interceptor的setProperties方法是空的实现类需要实现. 现在的实现方式是输出参数properties
public interface Interceptor {
Object intercept(Invocation invocation) throws Throwable;
default Object plugin(Object target) {
return Plugin.wrap(target, this);
}
default void setProperties(Properties properties) {
// NOP
}
}
-
跳出这个方法，通过 debug 查看下面这个方法的返回值
this.configuration.getInterceptors()
-
指向了我们刚才编写的插件类，为了测试在插件类编写
public String hello() { return "hello-mybatis-plugins";}
-
((TestPlugin) this.configuration.getInterceptors().get(0)).hello()
-
标签
<objectFactory>的解析 -
在
mybatis-config.xml中写入<objectFactory type="com.huifer.mybatis.factory.TestObjectFactory"> <property name="data" value="100"/> </objectFactory>
package com.huifer.mybatis.factory; import org.apache.ibatis.reflection.factory.ObjectFactory; import java.util.List; import java.util.Properties; public class TestObjectFactory implements ObjectFactory { private String data; public String getData() { return data; } public void setData(String data) { this.data = data; } /** * Sets configuration properties. * * @param properties configuration properties */ @Override public void setProperties(Properties properties) { this.data = properties.getProperty("data"); } /** * Creates a new object with default constructor. * * @param type Object type * @return */ @Override public <T> T create(Class<T> type) { return null; } /** * Creates a new object with the specified constructor and params. * * @param type Object type * @param constructorArgTypes Constructor argument types * @param constructorArgs Constructor argument values * @return */ @Override public <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) { return null; } /** * Returns true if this object can have a set of other objects. * It's main purpose is to support non-java.util.Collection objects like Scala collections. * * @param type Object type * @return whether it is a collection or not * @since 3.1.0 */ @Override public <T> boolean isCollection(Class<T> type) { return false; } }
-
objectFactoryElement方法的内容和其他标签的解析方式基本相同
private void objectFactoryElement(XNode context) throws Exception {
if (context != null) {
// 获取标签 objectFactory 中的 type 属性
String type = context.getStringAttribute("type");
Properties properties = context.getChildrenAsProperties();
// 去别名 MAP 中获取实例
ObjectFactory factory = (ObjectFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 设置属性值
factory.setProperties(properties);
// 在 configuration 中放入该工厂
configuration.setObjectFactory(factory);
}
}
-
解析
<objectWrapperFactory>标签 -
修改
mybatis-config.xml<objectWrapperFactory type="org.apache.ibatis.reflection.wrapper.DefaultObjectWrapperFactory"/>
private void objectWrapperFactoryElement(XNode context) throws Exception {
if (context != null) {
// 获取 objectWrapperFactory 标签 type 的值
String type = context.getStringAttribute("type");
// 别名 mao 中获取
ObjectWrapperFactory factory = (ObjectWrapperFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 在 configuration 设置
configuration.setObjectWrapperFactory(factory);
}
}
-
解析
<reflectorFactoryElement>标签 -
修改
mybatis-config.xml
<reflectorFactory type="org.apache.ibatis.reflection.DefaultReflectorFactory"/>- 源码和
objectWrapperFactoryElement方法相同的解析过程.
/**
* 解析 reflectorFactory 标签
*
* @param context
* @throws Exception
*/
private void reflectorFactoryElement(XNode context) throws Exception {
if (context != null) {
// 获取 reflectorFactory 标签 type 的值
String type = context.getStringAttribute("type");
// 别名 mao 中获取
ReflectorFactory factory = (ReflectorFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 在 configuration 设置
configuration.setReflectorFactory(factory);
}
}- 这个方法的作用是将xml解析道德内容放入
org.apache.ibatis.session.Configuration中
/**
* 该方法将settings标签内的数据放到 {@link Configuration}
*
* @param props settings 标签的内容
*/
private void settingsElement(Properties props) {
configuration.setAutoMappingBehavior(AutoMappingBehavior.valueOf(props.getProperty("autoMappingBehavior", "PARTIAL")));
configuration.setAutoMappingUnknownColumnBehavior(AutoMappingUnknownColumnBehavior.valueOf(props.getProperty("autoMappingUnknownColumnBehavior", "NONE")));
configuration.setCacheEnabled(booleanValueOf(props.getProperty("cacheEnabled"), true));
configuration.setProxyFactory((ProxyFactory) createInstance(props.getProperty("proxyFactory")));
configuration.setLazyLoadingEnabled(booleanValueOf(props.getProperty("lazyLoadingEnabled"), false));
configuration.setAggressiveLazyLoading(booleanValueOf(props.getProperty("aggressiveLazyLoading"), false));
configuration.setMultipleResultSetsEnabled(booleanValueOf(props.getProperty("multipleResultSetsEnabled"), true));
configuration.setUseColumnLabel(booleanValueOf(props.getProperty("useColumnLabel"), true));
configuration.setUseGeneratedKeys(booleanValueOf(props.getProperty("useGeneratedKeys"), false));
configuration.setDefaultExecutorType(ExecutorType.valueOf(props.getProperty("defaultExecutorType", "SIMPLE")));
configuration.setDefaultStatementTimeout(integerValueOf(props.getProperty("defaultStatementTimeout"), null));
configuration.setDefaultFetchSize(integerValueOf(props.getProperty("defaultFetchSize"), null));
configuration.setDefaultResultSetType(resolveResultSetType(props.getProperty("defaultResultSetType")));
configuration.setMapUnderscoreToCamelCase(booleanValueOf(props.getProperty("mapUnderscoreToCamelCase"), false));
configuration.setSafeRowBoundsEnabled(booleanValueOf(props.getProperty("safeRowBoundsEnabled"), false));
configuration.setLocalCacheScope(LocalCacheScope.valueOf(props.getProperty("localCacheScope", "SESSION")));
configuration.setJdbcTypeForNull(JdbcType.valueOf(props.getProperty("jdbcTypeForNull", "OTHER")));
configuration.setLazyLoadTriggerMethods(stringSetValueOf(props.getProperty("lazyLoadTriggerMethods"), "equals,clone,hashCode,toString"));
configuration.setSafeResultHandlerEnabled(booleanValueOf(props.getProperty("safeResultHandlerEnabled"), true));
configuration.setDefaultScriptingLanguage(resolveClass(props.getProperty("defaultScriptingLanguage")));
configuration.setDefaultEnumTypeHandler(resolveClass(props.getProperty("defaultEnumTypeHandler")));
configuration.setCallSettersOnNulls(booleanValueOf(props.getProperty("callSettersOnNulls"), false));
configuration.setUseActualParamName(booleanValueOf(props.getProperty("useActualParamName"), true));
configuration.setReturnInstanceForEmptyRow(booleanValueOf(props.getProperty("returnInstanceForEmptyRow"), false));
configuration.setLogPrefix(props.getProperty("logPrefix"));
configuration.setConfigurationFactory(resolveClass(props.getProperty("configurationFactory")));
}- 先修改配置
mybatis-config.xml
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>- 这个
environments标签下我们会有多个数据源的填写操作,所以代码中应该会有循环来解析environment标签, 代码如下 。
/**
* 解析 environments 标签
*
* @param context
* @throws Exception
*/
private void environmentsElement(XNode context) throws Exception {
if (context != null) {
if (environment == null) {
// environment 初始化的是就是空
environment = context.getStringAttribute("default");
}
for (XNode child : context.getChildren()) {
// 获取 environment 的 id
String id = child.getStringAttribute("id");
if (isSpecifiedEnvironment(id)) {
// 解析 transactionManager
TransactionFactory txFactory = transactionManagerElement(child.evalNode("transactionManager"));
// 解析 dataSource
DataSourceFactory dsFactory = dataSourceElement(child.evalNode("dataSource"));
// 获取数据库
DataSource dataSource = dsFactory.getDataSource();
// 构建
Environment.Builder environmentBuilder = new Environment.Builder(id)
.transactionFactory(txFactory)
.dataSource(dataSource);
// 在 configuration 设置
configuration.setEnvironment(environmentBuilder.build());
}
}
}
} /**
* 解析 transactionManager 标签
* <transactionManager type="JDBC"/>
*
* @param context
* @return
* @throws Exception
*/
private TransactionFactory transactionManagerElement(XNode context) throws Exception {
if (context != null) {
// 获取 type 属性
String type = context.getStringAttribute("type");
Properties props = context.getChildrenAsProperties();
TransactionFactory factory = (TransactionFactory) resolveClass(type).getDeclaredConstructor().newInstance();
factory.setProperties(props);
return factory;
}
throw new BuilderException("Environment declaration requires a TransactionFactory.");
} /**
* 解析 dataSourceElement 标签
* <dataSource type="POOLED">
* <property name="driver" value="com.mysql.jdbc.Driver"/>
* <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
* <property name="username" value="root"/>
* <property name="password" value="root"/>
* </dataSource>
*
* @param context
* @return
* @throws Exception
*/
private DataSourceFactory dataSourceElement(XNode context) throws Exception {
if (context != null) {
String type = context.getStringAttribute("type");
Properties props = context.getChildrenAsProperties();
//org.apache.ibatis.datasource.unpooled.UnpooledDataSourceFactory.setProperties
DataSourceFactory factory = (DataSourceFactory) resolveClass(type).getDeclaredConstructor().newInstance();
factory.setProperties(props);
return factory;
}
throw new BuilderException("Environment declaration requires a DataSourceFactory.");
}- 这部分有话说! 此时通过
type我们可以知道当前值为:POOLED那么他的别名背后的类是那一个,从哪里寻找. 这一点之前源码中没有描述,补充一下在org.apache.ibatis.session.Configuration.Configuration()构造中
public Configuration() {
typeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);
typeAliasRegistry.registerAlias("MANAGED", ManagedTransactionFactory.class);
typeAliasRegistry.registerAlias("JNDI", JndiDataSourceFactory.class);
typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);
typeAliasRegistry.registerAlias("UNPOOLED", UnpooledDataSourceFactory.class);
typeAliasRegistry.registerAlias("PERPETUAL", PerpetualCache.class);
typeAliasRegistry.registerAlias("FIFO", FifoCache.class);
typeAliasRegistry.registerAlias("LRU", LruCache.class);
typeAliasRegistry.registerAlias("SOFT", SoftCache.class);
typeAliasRegistry.registerAlias("WEAK", WeakCache.class);
typeAliasRegistry.registerAlias("DB_VENDOR", VendorDatabaseIdProvider.class);
typeAliasRegistry.registerAlias("XML", XMLLanguageDriver.class);
typeAliasRegistry.registerAlias("RAW", RawLanguageDriver.class);
typeAliasRegistry.registerAlias("SLF4J", Slf4jImpl.class);
typeAliasRegistry.registerAlias("COMMONS_LOGGING", JakartaCommonsLoggingImpl.class);
typeAliasRegistry.registerAlias("LOG4J", Log4jImpl.class);
typeAliasRegistry.registerAlias("LOG4J2", Log4j2Impl.class);
typeAliasRegistry.registerAlias("JDK_LOGGING", Jdk14LoggingImpl.class);
typeAliasRegistry.registerAlias("STDOUT_LOGGING", StdOutImpl.class);
typeAliasRegistry.registerAlias("NO_LOGGING", NoLoggingImpl.class);
typeAliasRegistry.registerAlias("CGLIB", CglibProxyFactory.class);
typeAliasRegistry.registerAlias("JAVASSIST", JavassistProxyFactory.class);
languageRegistry.setDefaultDriverClass(XMLLanguageDriver.class);
languageRegistry.register(RawLanguageDriver.class);
}
public class PooledDataSourceFactory extends UnpooledDataSourceFactory {
public PooledDataSourceFactory() {
this.dataSource = new PooledDataSource();
}
}public class UnpooledDataSourceFactory implements DataSourceFactory {
private static final String DRIVER_PROPERTY_PREFIX = "driver.";
private static final int DRIVER_PROPERTY_PREFIX_LENGTH = DRIVER_PROPERTY_PREFIX.length();
protected DataSource dataSource;
public UnpooledDataSourceFactory() {
this.dataSource = new UnpooledDataSource();
}
@Override
public void setProperties(Properties properties) {
Properties driverProperties = new Properties();
MetaObject metaDataSource = SystemMetaObject.forObject(dataSource);
for (Object key : properties.keySet()) {
String propertyName = (String) key;
if (propertyName.startsWith(DRIVER_PROPERTY_PREFIX)) {
String value = properties.getProperty(propertyName);
driverProperties.setProperty(propertyName.substring(DRIVER_PROPERTY_PREFIX_LENGTH), value);
} else if (metaDataSource.hasSetter(propertyName)) {
String value = (String) properties.get(propertyName);
Object convertedValue = convertValue(metaDataSource, propertyName, value);
metaDataSource.setValue(propertyName, convertedValue);
} else {
throw new DataSourceException("Unknown DataSource property: " + propertyName);
}
}
if (driverProperties.size() > 0) {
metaDataSource.setValue("driverProperties", driverProperties);
}
}
@Override
public DataSource getDataSource() {
return dataSource;
}
private Object convertValue(MetaObject metaDataSource, String propertyName, String value) {
Object convertedValue = value;
Class<?> targetType = metaDataSource.getSetterType(propertyName);
if (targetType == Integer.class || targetType == int.class) {
convertedValue = Integer.valueOf(value);
} else if (targetType == Long.class || targetType == long.class) {
convertedValue = Long.valueOf(value);
} else if (targetType == Boolean.class || targetType == boolean.class) {
convertedValue = Boolean.valueOf(value);
}
return convertedValue;
}
}类图
private DataSourceFactory dataSourceElement(XNode context) throws Exception {
if (context != null) {
String type = context.getStringAttribute("type");
Properties props = context.getChildrenAsProperties();
//org.apache.ibatis.session.Configuration.Configuration()
DataSourceFactory factory = (DataSourceFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// PooledDataSourceFactory -> UnpooledDataSourceFactory
factory.setProperties(props);
return factory;
}
throw new BuilderException("Environment declaration requires a DataSourceFactory.");
} factory.setProperties(props);设置jdbc链接相关的属性值
@Override
public void setProperties(Properties properties) {
Properties driverProperties = new Properties();
//metaDataSource 现在是一个dataSource
MetaObject metaDataSource = SystemMetaObject.forObject(dataSource);
for (Object key : properties.keySet()) {
String propertyName = (String) key;
if (propertyName.startsWith(DRIVER_PROPERTY_PREFIX)) {
// 如果是 driver. 前缀开头
String value = properties.getProperty(propertyName);
driverProperties.setProperty(propertyName.substring(DRIVER_PROPERTY_PREFIX_LENGTH), value);
} else if (metaDataSource.hasSetter(propertyName)) {
String value = (String) properties.get(propertyName);
Object convertedValue = convertValue(metaDataSource, propertyName, value);
// 通过 metaDataSource 来对 dataSource 进行设置属性
metaDataSource.setValue(propertyName, convertedValue);
} else {
throw new DataSourceException("Unknown DataSource property: " + propertyName);
}
}
if (driverProperties.size() > 0) {
metaDataSource.setValue("driverProperties", driverProperties);
}
}
debug 第一次进来
此时拿到的key=password 程序会设置password
此时的密码是root
执行metaDataSource.setValue(propertyName, convertedValue);
方法走过去此时dataSource的password属性被设置了
environmentsElement方法还有两个
// 构建
Environment.Builder environmentBuilder = new Environment.Builder(id)
.transactionFactory(txFactory)
.dataSource(dataSource);
// 在 configuration 设置
configuration.setEnvironment(environmentBuilder.build());/**
* <environment id="development">
* <transactionManager type="JDBC"/>
* <dataSource type="POOLED">
* <property name="driver" value="com.mysql.jdbc.Driver"/>
* <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
* <property name="username" value="root"/>
* <property name="password" value="root"/>
* </dataSource>
* </environment>
*/
public final class Environment {
/**
* <environment id="development">
*/
private final String id;
/**
* <transactionManager type="JDBC"/>
* {@link Configuration#Configuration()}
* {@link JdbcTransactionFactory}
*/
private final TransactionFactory transactionFactory;
/**
* * <dataSource type="POOLED">
* * <property name="driver" value="com.mysql.jdbc.Driver"/>
* * <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
* * <property name="username" value="root"/>
* * <property name="password" value="root"/>
* * </dataSource>
*/
private final DataSource dataSource;
public Environment(String id, TransactionFactory transactionFactory, DataSource dataSource) {
if (id == null) {
throw new IllegalArgumentException("Parameter 'id' must not be null");
}
if (transactionFactory == null) {
throw new IllegalArgumentException("Parameter 'transactionFactory' must not be null");
}
this.id = id;
if (dataSource == null) {
throw new IllegalArgumentException("Parameter 'dataSource' must not be null");
}
this.transactionFactory = transactionFactory;
this.dataSource = dataSource;
}
public String getId() {
return this.id;
}
public TransactionFactory getTransactionFactory() {
return this.transactionFactory;
}
public DataSource getDataSource() {
return this.dataSource;
}
public static class Builder {
private final String id;
private TransactionFactory transactionFactory;
private DataSource dataSource;
public Builder(String id) {
this.id = id;
}
public Builder transactionFactory(TransactionFactory transactionFactory) {
this.transactionFactory = transactionFactory;
return this;
}
public Builder dataSource(DataSource dataSource) {
this.dataSource = dataSource;
return this;
}
public String id() {
return this.id;
}
public Environment build() {
return new Environment(this.id, this.transactionFactory, this.dataSource);
}
}
}- 修改
mybatis-config.xml
<databaseIdProvider type="DB_VENDOR">
<property name="Oracle" value="oracle"/>
<property name="MySQL" value="mysql"/>
<property name="DB2" value="d2"/>
</databaseIdProvider>
回到org.apache.ibatis.session.Configuration类
搜索DB_VENDOR
typeAliasRegistry.registerAlias("DB_VENDOR", VendorDatabaseIdProvider.class); // 向 VendorDatabaseIdProvider 放入解析标签后的结果
Properties properties = context.getChildrenAsProperties();
databaseIdProvider = (DatabaseIdProvider) resolveClass(type).getDeclaredConstructor().newInstance();
databaseIdProvider.setProperties(properties);
}
Environment environment = configuration.getEnvironment();
if (environment != null && databaseIdProvider != null) {
// 从 configuration 获取 environment 标签的内容 在通过
String databaseId = databaseIdProvider.getDatabaseId(environment.getDataSource());
configuration.setDatabaseId(databaseId);
}- 解析下面这段代码
String databaseId = databaseIdProvider.getDatabaseId(environment.getDataSource()); /**
* 获取数据库名称 MySQL
* 核心内容是JDBC 相关的 java.sql
*
* @param dataSource
* @return
* @throws SQLException
*/
private String getDatabaseProductName(DataSource dataSource) throws SQLException {
Connection con = null;
try {
con = dataSource.getConnection();
DatabaseMetaData metaData = con.getMetaData();
return metaData.getDatabaseProductName();
} finally {
if (con != null) {
try {
con.close();
} catch (SQLException e) {
// ignored
}
}
}
}
有了上面两张图片的内容再看下面这个方法就明了了
/**
* 通过数据源获取数据库类型名称
*
* @param dataSource
* @return
* @throws SQLException
*/
private String getDatabaseName(DataSource dataSource) throws SQLException {
String productName = getDatabaseProductName(dataSource);
if (this.properties != null) {
// 通过获取到的数据库类型 获取 属性值的小写
// properties 就是
// <databaseIdProvider type="DB_VENDOR">
// <property name="Oracle" value="oracle"/>
// <property name="MySQL" value="mysql"/>
// <property name="DB2" value="d2"/>
// </databaseIdProvider>
for (Map.Entry<Object, Object> property : properties.entrySet()) {
if (productName.contains((String) property.getKey())) {
return (String) property.getValue();
}
}
// no match, return null
return null;
}
return productName;
}在走一步
/**
* 返回数据源名称
* 返回的是 mysql
* <databaseIdProvider type="DB_VENDOR">
* <property name="Oracle" value="oracle"/>
* <property name="MySQL" value="mysql"/>
* <property name="DB2" value="d2"/>
* </databaseIdProvider>
*
* @param dataSource
* @return
*/
@Override
public String getDatabaseId(DataSource dataSource) {
if (dataSource == null) {
throw new NullPointerException("dataSource cannot be null");
}
try {
return getDatabaseName(dataSource);
} catch (Exception e) {
LogHolder.log.error("Could not get a databaseId from dataSource", e);
}
return null;
}
最终我们获取到了mysql 这个字符加载也就结束了
- 修改
mybatis-config.xml
<typeHandlers>
<typeHandler jdbcType="varchar" javaType="String" handler="com.huifer.mybatis.handler.TestTypeHandler"/>
</typeHandlers> /**
* 解析 typeHandler
* 最终调用方法：{@link TypeHandlerRegistry#register(java.lang.reflect.Type, org.apache.ibatis.type.JdbcType, org.apache.ibatis.type.TypeHandler)}
*
*
* <typeHandlers>
* <!-- <package name="com.huifer.mybatis.handler"/>-->
* <typeHandler jdbcType="VARCHAR" javaType="String" handler="com.huifer.mybatis.handler.TestTypeHandler"/>
* </typeHandlers>
*
* @param parent
*/
private void typeHandlerElement(XNode parent) {
if (parent != null) {
for (XNode child : parent.getChildren()) {
if ("package".equals(child.getName())) {
// 获取 package 的 name 属性
String typeHandlerPackage = child.getStringAttribute("name");
// 注册
typeHandlerRegistry.register(typeHandlerPackage);
} else {
// 获取 javaType 属性值
String javaTypeName = child.getStringAttribute("javaType");
// 获取 jdbcType 属性值
String jdbcTypeName = child.getStringAttribute("jdbcType");
// 获取 handler 属性值
String handlerTypeName = child.getStringAttribute("handler");
// org.apache.ibatis.type.TypeAliasRegistry.TypeAliasRegistry 构造方法中有默认的
// 从别名中获取
Class<?> javaTypeClass = resolveClass(javaTypeName);
JdbcType jdbcType = resolveJdbcType(jdbcTypeName);
Class<?> typeHandlerClass = resolveClass(handlerTypeName);
if (javaTypeClass != null) {
if (jdbcType == null) {
typeHandlerRegistry.register(javaTypeClass, typeHandlerClass);
} else {
typeHandlerRegistry.register(javaTypeClass, jdbcType, typeHandlerClass);
}
} else {
typeHandlerRegistry.register(typeHandlerClass);
}
}
}
}
} /**
* * 注册方法 , 将 类型处理字节码注册到 allTypeHandlersMap
*
* @param javaType
* @param jdbcType
* @param handler
*/
private void register(Type javaType, JdbcType jdbcType, TypeHandler<?> handler) {
if (javaType != null) {
// 在 默认的 typeHandlerMap 获取 javaType 的子集
Map<JdbcType, TypeHandler<?>> map = typeHandlerMap.get(javaType);
if (map == null || map == NULL_TYPE_HANDLER_MAP) {
map = new HashMap<>();
typeHandlerMap.put(javaType, map);
}
// 在 所选的 javaType 中注册 TypeHandler
map.put(jdbcType, handler);
}
allTypeHandlersMap.put(handler.getClass(), handler);
}- 默认的TypeHandler
- 添加一条自己的TypeHandler
-
org.apache.ibatis.builder.xml.XMLConfigBuilder#mapperElement/** * 解析 mappers * * @param parent * @throws Exception */ private void mapperElement(XNode parent) throws Exception { if (parent != null) { for (XNode child : parent.getChildren()) { if ("package".equals(child.getName())) { String mapperPackage = child.getStringAttribute("name"); configuration.addMappers(mapperPackage); } else { // 读取 resource 属性 String resource = child.getStringAttribute("resource"); // 读取 url 属性 String url = child.getStringAttribute("url"); // 读取 class 属性 String mapperClass = child.getStringAttribute("class"); if (resource != null && url == null && mapperClass == null) { // 加载 resource 内容 ErrorContext.instance().resource(resource); InputStream inputStream = Resources.getResourceAsStream(resource); // 解析 mapper.xml 文件 XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, resource, configuration.getSqlFragments()); mapperParser.parse(); } else if (resource == null && url != null && mapperClass == null) { ErrorContext.instance().resource(url); InputStream inputStream = Resources.getUrlAsStream(url); XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, url, configuration.getSqlFragments()); mapperParser.parse(); } else if (resource == null && url == null && mapperClass != null) { Class<?> mapperInterface = Resources.classForName(mapperClass); configuration.addMapper(mapperInterface); } else { throw new BuilderException("A mapper element may only specify a url, resource or class, but not more than one."); } } } } }
-
编辑
mybatis-config.xml<mappers> <mapper resource="com/huifer/mybatis/mapper/PersonMapper.xml"/></mappers>
-
解析
Mapper.xml<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.huifer.mybatis.mapper.PersonMapper"> <cache-ref namespace="com.huifer.mybatis.mapper.PersonMapper"/> <resultMap id="base" type="com.huifer.mybatis.entity.Person" > <id column="ID" jdbcType="VARCHAR" property="id" /> <result column="age" jdbcType="INTEGER" property="age"/> <collection property="name" jdbcType="VARCHAR"/> </resultMap> <!-- <cache blocking="" eviction="" flushInterval="" readOnly="" size="" type=""/>--> <parameterMap id="hc" type="com.huifer.mybatis.entity.PersonQuery"> <parameter property="name" resultMap="base" jdbcType="VARCHAR"/> </parameterMap> <sql id="Base_List"> name,age,phone,email,address </sql> <insert id="insert" parameterType="Person" keyProperty="id" useGeneratedKeys="true"> INSERT INTO person (name, age, phone, email, address) VALUES(#{name},#{age},#{phone},#{email},#{address}) </insert> </mapper>
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#XMLMapperBuilder(java.io.InputStream, org.apache.ibatis.session.Configuration, java.lang.String, java.util.Map<java.lang.String,org.apache.ibatis.parsing.XNode>) -
/** * @param inputStream mapper.xml 文件流 * @param configuration 全局的配置文件 * @param resource mapper.xml 文件路径/com/../.. * @param sqlFragments 配置里面的内容 */ public XMLMapperBuilder(InputStream inputStream, Configuration configuration, String resource, Map<String, XNode> sqlFragments) { this(new XPathParser(inputStream, true, configuration.getVariables(), new XMLMapperEntityResolver()), configuration, resource, sqlFragments); }
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#parse
public void parse() {
if (!configuration.isResourceLoaded(resource)) {
// 解析 mapper 标签下的内容
configurationElement(parser.evalNode("/mapper"));
configuration.addLoadedResource(resource);
bindMapperForNamespace();
}
parsePendingResultMaps();
parsePendingCacheRefs();
parsePendingStatements();
}org.apache.ibatis.builder.xml.XMLMapperBuilder#configurationElement
/**
* 解析 mapper 标签
* <mapper resource="com/huifer/mybatis/mapper/PersonMapper.xml"/>
* <mapper namespace="com.huifer.mybatis.mapper.PersonMapper">
* <p>
* <cache-ref namespace="com.huifer.mybatis.mapper.PersonMapper"/>
* <resultMap id="base" type="com.huifer.mybatis.entity.Person">
* <id column="ID" jdbcType="VARCHAR" property="id"/>
* <result column="age" jdbcType="INTEGER" property="age"/>
* </resultMap>
*
* <parameterMap id="hc" type="com.huifer.mybatis.entity.PersonQuery">
* <parameter property="name" resultMap="base"/>
* </parameterMap>
* <sql id="Base_List">
* name,age,phone,email,address
* </sql>
* <insert id="insert" parameterType="Person" keyProperty="id"
* useGeneratedKeys="true">
* INSERT INTO person (name, age, phone, email, address)
* VALUES(#{name},#{age},#{phone},#{email},#{address})
* </insert>
* </mapper>
*
* @param context
*/
private void configurationElement(XNode context) {
try {
// 获取 namespace 属性
String namespace = context.getStringAttribute("namespace");
if (namespace == null || namespace.equals("")) {
throw new BuilderException("Mapper's namespace cannot be empty");
}
// 直接设置 namespace 属性不做其他操作普通的 setter 方法
builderAssistant.setCurrentNamespace(namespace);
// <cache-ref namespace="com.huifer.mybatis.mapper.PersonMapper"/>
cacheRefElement(context.evalNode("cache-ref"));
// <cache blocking="" eviction="" flushInterval="" readOnly="" size="" type=""/>
cacheElement(context.evalNode("cache"));
// <parameterMap id="hc" type="com.huifer.mybatis.entity.PersonQuery">
parameterMapElement(context.evalNodes("/mapper/parameterMap"));
// <resultMap id="base" type="com.huifer.mybatis.entity.Person">
resultMapElements(context.evalNodes("/mapper/resultMap"));
// <sql id="Base_List">
//name,age,phone,email,address
//</sql>
sqlElement(context.evalNodes("/mapper/sql"));
// 解析 select|insert|update|delete 标签
buildStatementFromContext(context.evalNodes("select|insert|update|delete"));
} catch (Exception e) {
throw new BuilderException("Error parsing Mapper XML. The XML location is '" + resource + "'. Cause: " + e, e);
}
}这个方法解析了mapper.xml的内容
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#cacheRefElement/** * 解析 <cache-ref namespace=""/> 标签的属性 * * @param context */ private void cacheRefElement(XNode context) { if (context != null) { configuration.addCacheRef(builderAssistant.getCurrentNamespace(), context.getStringAttribute("namespace")); // 构造 CacheRefResolver cacheRefResolver = new CacheRefResolver(builderAssistant, context.getStringAttribute("namespace")); try { cacheRefResolver.resolveCacheRef(); } catch (IncompleteElementException e) { // 初始化是没有内容走这一步 configuration.addIncompleteCacheRef(cacheRefResolver); } } }
/** * 向 cacheRefMap 插入值 * <mapper namespace="com.huifer.mybatis.mapper.PersonMapper"> * <p> * <cache-ref namespace="com.huifer.mybatis.mapper.PersonMapper"/> * * @param namespace mapper 的 namespace * @param referencedNamespace cache-ref 的 namespace */ public void addCacheRef(String namespace, String referencedNamespace) { cacheRefMap.put(namespace, referencedNamespace); }
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#cacheElement/** * 解析 * <cache blocking="" eviction="" flushInterval="" readOnly="" size="" type=""/> * 具体缓存策略查看{@link org.apache.ibatis.cache.decorators} 下的类 * 获取每个属性构造成 {@link Cache} * * @param context */ private void cacheElement(XNode context) { if (context != null) { // org.apache.ibatis.cache.impl.PerpetualCache 默认缓存实现 String type = context.getStringAttribute("type", "PERPETUAL"); // 添加到别名,或者从别名中获取 Class<? extends Cache> typeClass = typeAliasRegistry.resolveAlias(type); // 緩存策略 LRU 最近最少使用的：移除最长时间不被使用的对象。 String eviction = context.getStringAttribute("eviction", "LRU"); Class<? extends Cache> evictionClass = typeAliasRegistry.resolveAlias(eviction); // 刷新时间 单位 毫秒 Long flushInterval = context.getLongAttribute("flushInterval"); // 引用数量 Integer size = context.getIntAttribute("size"); // 只读 boolean readWrite = !context.getBooleanAttribute("readOnly", false); // boolean blocking = context.getBooleanAttribute("blocking", false); // <properties> 下级属性 Properties props = context.getChildrenAsProperties(); // 构造 cache builderAssistant.useNewCache(typeClass, evictionClass, flushInterval, size, readWrite, blocking, props); } }
默认实现方式
typeAliasRegistry.registerAlias("PERPETUAL", PerpetualCache.class); typeAliasRegistry.registerAlias("LRU", LruCache.class);
不难发现这两个属性和默认值的属性相同
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#parameterMapElement/** * 解析 parameterMap 标签的内容 * <parameterMap id="hc" type="com.huifer.mybatis.entity.PersonQuery"> * <parameter property="name" resultMap="base"/> * </parameterMap> * * @param list */ private void parameterMapElement(List<XNode> list) { for (XNode parameterMapNode : list) { // 获取标签属性值 String id = parameterMapNode.getStringAttribute("id"); String type = parameterMapNode.getStringAttribute("type"); // 到别名map中注册 Class<?> parameterClass = resolveClass(type); // 获取下级标签 parameter 的属性值 List<XNode> parameterNodes = parameterMapNode.evalNodes("parameter"); List<ParameterMapping> parameterMappings = new ArrayList<>(); for (XNode parameterNode : parameterNodes) { // 遍历下级节点获取属性 String property = parameterNode.getStringAttribute("property"); String javaType = parameterNode.getStringAttribute("javaType"); String jdbcType = parameterNode.getStringAttribute("jdbcType"); String resultMap = parameterNode.getStringAttribute("resultMap"); String mode = parameterNode.getStringAttribute("mode"); String typeHandler = parameterNode.getStringAttribute("typeHandler"); Integer numericScale = parameterNode.getIntAttribute("numericScale"); ParameterMode modeEnum = resolveParameterMode(mode); Class<?> javaTypeClass = resolveClass(javaType); JdbcType jdbcTypeEnum = resolveJdbcType(jdbcType); Class<? extends TypeHandler<?>> typeHandlerClass = resolveClass(typeHandler); ParameterMapping parameterMapping = builderAssistant.buildParameterMapping(parameterClass, property, javaTypeClass, jdbcTypeEnum, resultMap, modeEnum, typeHandlerClass, numericScale); parameterMappings.add(parameterMapping); } builderAssistant.addParameterMap(id, parameterClass, parameterMappings); } }
/** * 向 {@link Configuration} configuration 添加 parameter 标签的内容 * * @param id * @param parameterClass * @param parameterMappings * @return */ public ParameterMap addParameterMap(String id, Class<?> parameterClass, List<ParameterMapping> parameterMappings) { id = applyCurrentNamespace(id, false); ParameterMap parameterMap = new ParameterMap.Builder(configuration, id, parameterClass, parameterMappings).build(); configuration.addParameterMap(parameterMap); return parameterMap; }
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#resultMapElements/** * 解析 resultMap 标签 * * @param list * @throws Exception */ private void resultMapElements(List<XNode> list) throws Exception { for (XNode resultMapNode : list) { try { resultMapElement(resultMapNode); } catch (IncompleteElementException e) { // ignore, it will be retried } } }
/**
* reslutMapper 下级标签解析
* <resultMap type="com.huifer.mybatis.entity.Person" id="base">
* <id jdbcType="VARCHAR" column="ID" property="id"/>
* <result jdbcType="INTEGER" column="age" property="age"/>
* </resultMap>
*
* @param resultMapNode resultMap 节点
* @param additionalResultMappings
* @param enclosingType
* @return
* @throws Exception
*/
private ResultMap resultMapElement(XNode resultMapNode, List<ResultMapping> additionalResultMappings, Class<?> enclosingType) throws Exception {
ErrorContext.instance().activity("processing " + resultMapNode.getValueBasedIdentifier());
String type = resultMapNode.getStringAttribute("type",
resultMapNode.getStringAttribute("ofType",
resultMapNode.getStringAttribute("resultType",
resultMapNode.getStringAttribute("javaType"))));
// 别名注册
Class<?> typeClass = resolveClass(type);
if (typeClass == null) {
typeClass = inheritEnclosingType(resultMapNode, enclosingType);
}
Discriminator discriminator = null;
List<ResultMapping> resultMappings = new ArrayList<>();
// 粗暴
resultMappings.addAll(additionalResultMappings);
List<XNode> resultChildren = resultMapNode.getChildren();
for (XNode resultChild : resultChildren) {
if ("constructor".equals(resultChild.getName())) {
processConstructorElement(resultChild, typeClass, resultMappings);
} else if ("discriminator".equals(resultChild.getName())) {
discriminator = processDiscriminatorElement(resultChild, typeClass, resultMappings);
} else {
List<ResultFlag> flags = new ArrayList<>();
if ("id".equals(resultChild.getName())) {
// 获取 id 属性
flags.add(ResultFlag.ID);
}
resultMappings.add(buildResultMappingFromContext(resultChild, typeClass, flags));
}
}
// 解析xml 中的resultMap标签
// mapper_resultMap[base]_collection[name]
String id = resultMapNode.getStringAttribute("id",
resultMapNode.getValueBasedIdentifier());
String extend = resultMapNode.getStringAttribute("extends");
Boolean autoMapping = resultMapNode.getBooleanAttribute("autoMapping");
ResultMapResolver resultMapResolver = new ResultMapResolver(builderAssistant, id, typeClass, extend, discriminator, resultMappings, autoMapping);
try {
return resultMapResolver.resolve();
} catch (IncompleteElementException e) {
configuration.addIncompleteResultMap(resultMapResolver);
throw e;
}
}
public ResultMap resolve() {
return assistant.addResultMap(this.id, this.type, this.extend, this.discriminator, this.resultMappings, this.autoMapping);
} /**
* 添加 resultMap
*
* <resultMap id="base" type="com.huifer.mybatis.entity.Person">
* <id column="ID" jdbcType="VARCHAR" property="id"/>
* <result column="age" jdbcType="INTEGER" property="age"/>
* <collection property="name" jdbcType="VARCHAR"/>
* </resultMap>
* @param id resultMap 标签的 id 属性
* @param type resultMap 标签的 type 属性的字节码
* @param extend resultMap 标签的 extend 属性
* @param discriminator 下级标签
* @param resultMappings 夏季标签
* @param autoMapping resultMap 标签的 autoMapping 属性
* @return
*/
public ResultMap addResultMap(
String id,
Class<?> type,
String extend,
Discriminator discriminator,
List<ResultMapping> resultMappings,
Boolean autoMapping) {
id = applyCurrentNamespace(id, false);
extend = applyCurrentNamespace(extend, true);
if (extend != null) {
if (!configuration.hasResultMap(extend)) {
throw new IncompleteElementException("Could not find a parent resultmap with id '" + extend + "'");
}
ResultMap resultMap = configuration.getResultMap(extend);
List<ResultMapping> extendedResultMappings = new ArrayList<>(resultMap.getResultMappings());
extendedResultMappings.removeAll(resultMappings);
// Remove parent constructor if this resultMap declares a constructor.
boolean declaresConstructor = false;
for (ResultMapping resultMapping : resultMappings) {
if (resultMapping.getFlags().contains(ResultFlag.CONSTRUCTOR)) {
declaresConstructor = true;
break;
}
}
if (declaresConstructor) {
extendedResultMappings.removeIf(resultMapping -> resultMapping.getFlags().contains(ResultFlag.CONSTRUCTOR));
}
resultMappings.addAll(extendedResultMappings);
}
// 构建 ResultMap
ResultMap resultMap = new ResultMap.Builder(configuration, id, type, resultMappings, autoMapping)
.discriminator(discriminator)
.build();
configuration.addResultMap(resultMap);
return resultMap;
}他又来了configuration
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#sqlElement(java.util.List<org.apache.ibatis.parsing.XNode>)private void sqlElement(List<XNode> list) { if (configuration.getDatabaseId() != null) { sqlElement(list, configuration.getDatabaseId()); } sqlElement(list, null); }
private void sqlElement(List<XNode> list, String requiredDatabaseId) { for (XNode context : list) { String databaseId = context.getStringAttribute("databaseId"); // 获取 id String id = context.getStringAttribute("id"); id = builderAssistant.applyCurrentNamespace(id, false); if (databaseIdMatchesCurrent(id, databaseId, requiredDatabaseId)) { sqlFragments.put(id, context); } } }
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#buildStatementFromContext(java.util.List<org.apache.ibatis.parsing.XNode>)/** * select|insert|update|delete 标签 * * @param list select|insert|update|delete 标签 */ private void buildStatementFromContext(List<XNode> list) { if (configuration.getDatabaseId() != null) { buildStatementFromContext(list, configuration.getDatabaseId()); } buildStatementFromContext(list, null); }
/** * <insert keyProperty="id" parameterType="Person" useGeneratedKeys="true" id="insert"> * INSERT INTO person (name, age, phone, email, address) * VALUES(#{name},#{age},#{phone},#{email},#{address}) * </insert> * * <select resultMap="base" id="list"> * <include refid="Base_List"/> * <if test="iid != null"> * and id = #{iid,jdbcType=INTEGER} * </if> * </select> * * @param list * @param requiredDatabaseId */ private void buildStatementFromContext(List<XNode> list, String requiredDatabaseId) { for (XNode context : list) { // 动态 sql 解析 final XMLStatementBuilder statementParser = new XMLStatementBuilder(configuration, builderAssistant, context, requiredDatabaseId); try { // 解析 statementParser.parseStatementNode(); } catch (IncompleteElementException e) { configuration.addIncompleteStatement(statementParser); } } }
/** * context => <insert keyProperty="id" parameterType="Person" useGeneratedKeys="true" id="insert"> * INSERT INTO person (name, age, phone, email, address) * VALUES(#{name},#{age},#{phone},#{email},#{address}) * </insert> */ public void parseStatementNode() { // 获取id属性 String id = context.getStringAttribute("id"); String databaseId = context.getStringAttribute("databaseId"); if (!databaseIdMatchesCurrent(id, databaseId, this.requiredDatabaseId)) { return; } // 获取当前 <select insert delete update > 名称 String nodeName = context.getNode().getNodeName(); SqlCommandType sqlCommandType = SqlCommandType.valueOf(nodeName.toUpperCase(Locale.ENGLISH)); boolean isSelect = sqlCommandType == SqlCommandType.SELECT; boolean flushCache = context.getBooleanAttribute("flushCache", !isSelect); boolean useCache = context.getBooleanAttribute("useCache", isSelect); boolean resultOrdered = context.getBooleanAttribute("resultOrdered", false); // Include Fragments before parsing // <include > 解析 // TODO: 2019/12/17 include 标签 XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant); includeParser.applyIncludes(context.getNode()); //<select resultMap="base" id="list"> // <if test="iid != null"> // and id = #{iid,jdbcType=INTEGER} // </if> //</select> // 请求类型 String parameterType = context.getStringAttribute("parameterType"); // 别名中心注册获取 Class<?> parameterTypeClass = resolveClass(parameterType); String lang = context.getStringAttribute("lang"); LanguageDriver langDriver = getLanguageDriver(lang); // Parse selectKey after includes and remove them. processSelectKeyNodes(id, parameterTypeClass, langDriver); // Parse the SQL (pre: <selectKey> and <include> were parsed and removed) KeyGenerator keyGenerator; String keyStatementId = id + SelectKeyGenerator.SELECT_KEY_SUFFIX; keyStatementId = builderAssistant.applyCurrentNamespace(keyStatementId, true); if (configuration.hasKeyGenerator(keyStatementId)) { keyGenerator = configuration.getKeyGenerator(keyStatementId); } else { keyGenerator = context.getBooleanAttribute("useGeneratedKeys", configuration.isUseGeneratedKeys() && SqlCommandType.INSERT.equals(sqlCommandType)) ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE; } // 语言驱动： org.apache.ibatis.scripting.xmltags.XMLLanguageDriver // 创建sql源 SqlSource sqlSource = langDriver.createSqlSource(configuration, context, parameterTypeClass); StatementType statementType = StatementType.valueOf(context.getStringAttribute("statementType", StatementType.PREPARED.toString())); // 标签获取 Integer fetchSize = context.getIntAttribute("fetchSize"); Integer timeout = context.getIntAttribute("timeout"); String parameterMap = context.getStringAttribute("parameterMap"); String resultType = context.getStringAttribute("resultType"); Class<?> resultTypeClass = resolveClass(resultType); String resultMap = context.getStringAttribute("resultMap"); String resultSetType = context.getStringAttribute("resultSetType"); ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType); if (resultSetTypeEnum == null) { resultSetTypeEnum = configuration.getDefaultResultSetType(); } String keyProperty = context.getStringAttribute("keyProperty"); String keyColumn = context.getStringAttribute("keyColumn"); String resultSets = context.getStringAttribute("resultSets"); builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType, fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass, resultSetTypeEnum, flushCache, useCache, resultOrdered, keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets); }
相关类
org.apache.ibatis.builder.xml.XMLIncludeTransformerorg.apache.ibatis.builder.xml.XMLStatementBuilderorg.apache.ibatis.mapping.SqlCommandTypeorg.apache.ibatis.executor.keygen.KeyGeneratororg.apache.ibatis.scripting.LanguageDriverorg.apache.ibatis.mapping.SqlSourceorg.apache.ibatis.scripting.xmltags.XMLScriptBuilder- ...
debug
<select id="sss" resultMap="BaseResultMap">
select * from hs_sell
</select>
可以看到获取id属性为sss
/**
* 数据库的操作方式 CRUD
* @author Clinton Begin
*/
public enum SqlCommandType {
UNKNOWN, INSERT, UPDATE, DELETE, SELECT, FLUSH
}include 标签解析不明白,
XMLIncludeTransformer includeParser = new XMLIncludeTransformer(configuration, builderAssistant);
includeParser.applyIncludes(context.getNode());源码看的不明白 ， 核心内容就是将 <include>转换成具体的文本
看sqlSource 构建
SqlSource sqlSource = langDriver.createSqlSource(configuration, context, parameterTypeClass);
StatementType statementType = StatementType.valueOf(context.getStringAttribute("statementType", StatementType.PREPARED.toString())); @Override
public SqlSource createSqlSource(Configuration configuration, XNode script, Class<?> parameterType) {
XMLScriptBuilder builder = new XMLScriptBuilder(configuration, script, parameterType);
return builder.parseScriptNode();
} public SqlSource parseScriptNode() {
//<select resultMap="BaseResultMap" parameterType="java.lang.Integer" id="selectByPrimaryKey">
//
// select
// </select>
// select * from hs_sell
MixedSqlNode rootSqlNode = parseDynamicTags(context);
SqlSource sqlSource;
if (isDynamic) {
sqlSource = new DynamicSqlSource(configuration, rootSqlNode);
} else {
sqlSource = new RawSqlSource(configuration, rootSqlNode, parameterType);
}
return sqlSource;
}
/**
* <b>动态sql 的核心方法!!!</b>
*
* @param node
* @return
*/
protected MixedSqlNode parseDynamicTags(XNode node) {
List<SqlNode> contents = new ArrayList<>();
NodeList children = node.getNode().getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
XNode child = node.newXNode(children.item(i));
if (child.getNode().getNodeType() == Node.CDATA_SECTION_NODE || child.getNode().getNodeType() == Node.TEXT_NODE) {
// 如果不包含其他标签或者是纯文本节点
// data 是替换后sql文本
String data = child.getStringBody("");
TextSqlNode textSqlNode = new TextSqlNode(data);
if (textSqlNode.isDynamic()) {
contents.add(textSqlNode);
isDynamic = true;
} else {
// 直接添加
contents.add(new StaticTextSqlNode(data));
}
} else if (child.getNode().getNodeType() == Node.ELEMENT_NODE) { // issue #628
// 动态标签处理逻辑
String nodeName = child.getNode().getNodeName();
// if 等标签
NodeHandler handler = nodeHandlerMap.get(nodeName);
if (handler == null) {
throw new BuilderException("Unknown element <" + nodeName + "> in SQL statement.");
}
/**
* 动态标签处理 {@link TrimHandler}
*/
handler.handleNode(child, contents);
isDynamic = true;
}
}
return new MixedSqlNode(contents);
}-
当前sql是纯文本
select * from hs_sell
可以看到当前
child变量就是 -
动态解析
<trim suffixOverrides="," prefix="(" suffix=")"> <if test="userId != null"> USER_ID, </if> <if test="goodId != null"> GOOD_ID, </if> <if test="price != null"> PRICE, </if> <if test="size != null"> `SIZE`, </if> <if test="companyId != null"> COMPANY_ID, </if> <if test="groupId != null"> GROUP_ID, </if> <if test="version != null"> VERSION, </if> <if test="deleted != null"> DELETED, </if> <if test="createUser != null"> CREATE_USER, </if> <if test="createTime != null"> CREATE_TIME, </if> <if test="updateUser != null"> UPDATE_USER, </if> <if test="updateTime != null"> UPDATE_TIME, </if> <if test="workOrderId != null"> WORK_ORDER_ID, </if> </trim>
private interface NodeHandler { void handleNode(XNode nodeToHandle, List<SqlNode> targetContents); }
实现方法
处理后结果
Integer fetchSize = context.getIntAttribute("fetchSize"); Integer timeout = context.getIntAttribute("timeout"); String parameterMap = context.getStringAttribute("parameterMap"); String resultType = context.getStringAttribute("resultType"); Class<?> resultTypeClass = resolveClass(resultType); String resultMap = context.getStringAttribute("resultMap"); String resultSetType = context.getStringAttribute("resultSetType"); ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType); if (resultSetTypeEnum == null) { resultSetTypeEnum = configuration.getDefaultResultSetType(); } String keyProperty = context.getStringAttribute("keyProperty"); String keyColumn = context.getStringAttribute("keyColumn"); String resultSets = context.getStringAttribute("resultSets");
- 上述部分为属性值获取
-
org.apache.ibatis.builder.xml.XMLMapperBuilder#parsepublic void parse() { if (!configuration.isResourceLoaded(resource)) { // 解析 mapper 标签下的内容 configurationElement(parser.evalNode("/mapper")); // <mappers> //<!-- <mapper resource="com/huifer/mybatis/mapper/PersonMapper.xml"/>--> // <mapper resource="com/huifer/mybatis/mapper/HsSellMapper.xml"/> // </mappers> // 将 resource 属性值添加 configuration.addLoadedResource(resource); // mapper 和 namespace 绑定 bindMapperForNamespace(); } parsePendingResultMaps(); parsePendingCacheRefs(); parsePendingStatements(); }
private void bindMapperForNamespace() {
String namespace = builderAssistant.getCurrentNamespace();
if (namespace != null) {
Class<?> boundType = null;
try {
// 获取 mapper.xml 的namespace 属性值对应的字节码
boundType = Resources.classForName(namespace);
} catch (ClassNotFoundException e) {
//ignore, bound type is not required
}
if (boundType != null) {
if (!configuration.hasMapper(boundType)) {
// Spring may not know the real resource name so we set a flag
// to prevent loading again this resource from the mapper interface
// look at MapperAnnotationBuilder#loadXmlResource
// 添加操作
configuration.addLoadedResource("namespace:" + namespace);
configuration.addMapper(boundType);
}
}
}
}
- 解析完成了 :happy: