Create README.md

2023.06.15 「小马哥技术周报」- 第五十六期：Spring 容器并行 Bean 生命周期处理实现/README.md

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+# 底层实现
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+## 代码实现
+项目工程 - [microsphere-spring](https://github.com/microsphere-projects/microsphere-spring)<br />核心代码 - [io.microsphere.spring.context.event.ParallelBeanFactoryListener](https://github.com/microsphere-projects/microsphere-spring/blob/main/microsphere-spring-context/src/main/java/io/microsphere/spring/context/event/ParallelBeanFactoryListener.java)
+
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+# 知识贮备
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+## Spring 可依赖对象
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+### Spring Bean 对象
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+#### Spring BeanDefinition
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+##### Spring Class 级别 BeanDefinition
+指定 BeanDefinition class<br />指定 BeanDefinition class -> FactoryBean 实现<br />@Component AnnotatedBeanDefinition class = 配置类
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+##### Spring 工厂方法 BeanDefinition
+BeanDefinition#setFactoryBean (可选）
+
+- 如果存在的话，说明工厂方法是对象方法
+- 如果存在的话，说明工厂方法是类方法
+
+BeanDefinition#setFactoryMethod（可选）
+
+- 如果存在的话，Bean 会通过工厂方法来创建
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+##### Spring @Bean BeanDefinition
+Spring 3.0 + <br />Configuration class @Bean 方法声明<br />通过 AnnotatedBeanDefinition#getFactoryMethodMetadata() 获取 @Bean 方法信息
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+##### Spring Suppiler BeanDefinition
+Spring 5.0 + <br />BeanDefinition 执行 org.springframework.beans.factory.support.AbstractBeanDefinition#setInstanceSupplier<br />该 Bean 通过 AbstractBeanDefinition#getInstanceSupplier() 方法返回 Supplier 来获取<br /> 
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+#### Spring 外部注册的 Singleton 对象
+SingletonBeanRegistry#registerSingleton(String,Object)<br />被注册 Singleton 对象的生命周期由 IoC 容器外部管理，该对象是一个已准备就绪的 Bean
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+### Spring ResolvableDependency
+手动注册，AbstractApplicationContext
+```java
+	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
+    	...
+		beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
+		beanFactory.registerResolvableDependency(ResourceLoader.class, this);
+		beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
+		beanFactory.registerResolvableDependency(ApplicationContext.class, this);
+    	...
+	}
+```
+
+```java
+public class SomeBean {
+
+    @Autowired
+    private ApplicationContext context; // 非 Spring Bean，而是 ResolvableDependency
+
+    // 非 Spring Bean，而是 ResolvableDependency
+    @Autowired
+    private ConfigurableApplicationContext applicationContext; 
+
+    @Autowired
+    private EchoService echoService; // EchoService Spring Bean，通过类型依赖查找
+
+    @Autowired
+    @Qualifier("userService")
+    private UserService userService; // UserService Spring Bean，通过 @Qualifier 查找
+
+    @Autowird
+    private Map<String,UserService> userServices;
+}
+```
+
+SomeBean 实际上依赖的 Spring Beans：EchoService 和 UserService，需要进一步分析出两个类型对应的 Bean 名称。
+
+
+```java
+  public MybatisAutoConfiguration(MybatisProperties properties,
+      ObjectProvider<Interceptor[]> interceptorsProvider,
+      ObjectProvider<TypeHandler[]> typeHandlersProvider, 
+      ObjectProvider<LanguageDriver[]> languageDriversProvider,
+      ResourceLoader resourceLoader, 
+      ObjectProvider<DatabaseIdProvider> databaseIdProvider,
+      ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider,
+      ObjectProvider<List<SqlSessionFactoryBeanCustomizer>> sqlSessionFactoryBeanCustomizers) {
+    this.properties = properties;
+    this.interceptors = interceptorsProvider.getIfAvailable();
+    this.typeHandlers = typeHandlersProvider.getIfAvailable();
+    this.languageDrivers = languageDriversProvider.getIfAvailable();
+    this.resourceLoader = resourceLoader;
+    this.databaseIdProvider = databaseIdProvider.getIfAvailable();
+    this.configurationCustomizers = configurationCustomizersProvider.getIfAvailable();
+    this.sqlSessionFactoryBeanCustomizers = sqlSessionFactoryBeanCustomizers.getIfAvailable();
+  }
+```
+Spring Bean 类型：
+
+1. MybatisProperties
+   1. parameter.getParameterizedType() == MybatisProperties.class
+2. Interceptor - ObjectProvider<Interceptor[]>
+   1. parameter.getParameterizedType() == ObjectProvider<Interceptor[]>>
+      1. rawType = ObjectProvider.class
+      2. actualTypeParameters = 
+         1. [0] = Interceptor[].class
+3. TypeHandler - ObjectProvider<TypeHandler[]>
+   1. parameter.getParameterizedType() == ObjectProvider<TypeHandler[]>>
+      1. rawType = ObjectProvider.class
+      2. actualTypeParameters = 
+         1. [0] = TypeHandler[].class
+4. LanguageDriver - ObjectProvider<LanguageDriver[]>
+5. DatabaseIdProvider - ObjectProvider<DatabaseIdProvider>
+6. ConfigurationCustomizer - ObjectProvider<List<ConfigurationCustomizer>>
+   1. parameter.getParameterizedType() == ObjectProvider<List<ConfigurationCustomizer>>
+      1. rawType = ObjectProvider.class
+      2. actualTypeParameters = 
+         1. [0] = List<ConfigurationCustomizer>
+            1. rawType = List.class
+            2. actualTypeParameters = 
+               1. [0] = ConfigurationCustomizer.class
+7. SqlSessionFactoryBeanCustomizer - ObjectProvider<List<SqlSessionFactoryBeanCustomizer>>
+
+Spring ResovlableType：
+
+1. ResourceLoader
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+## Bean 作用域
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+### Singleton Scope Bean
+