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Java SDK
Java
SDK
Java SDK
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Java SDK

Overview

Maven coordinates

<dependency>
    <groupId>com.alibaba.nacos</groupId>
    <artifactId>nacos-client</artifactId>
    <version>${version}</version>
</dependency>

Note: Since version 2.0, the Nacos Java SDK introduced gRPC, and use shaded technology to directly encapsulate some dependencies into nacos-client in order to avoid conflicts caused by different versions of gRPC introduced by users, which resulting in a larger nacos-client. If the users don't introduce gRPC or confirms that there is no conflict between the versions, and wants to use the pure version of nacos-client to reduce dependencies, users can use the classifier to specify the pure version.

    <properties>
        <!-- Upper 2.1.2 support pure client -->
        <nacos.version>2.1.2</nacos.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.alibaba.nacos</groupId>
            <artifactId>nacos-client</artifactId>
            <version>${nacos.version}</version>
            <!--  specify the pure SDK -->
            <classifier>pure</classifier>
        </dependency>
        <!-- Same version of nacos-api and nacos-common must be introduced for pure SDK, otherwise there may be a problem that the class cannot be found at runtime -->
        <dependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>nacos-common</artifactId>
            <version>${nacos.version}</version>
        </dependency>
        <dependency>
            <groupId>${project.groupId}</groupId>
            <artifactId>nacos-api</artifactId>
            <version>${nacos.version}</version>
        </dependency>
    </dependencies>

Configuration Management

Get configuration

Description

Get configuration from Nacos when a service starts.

public String getConfig(String dataId, String group, long timeoutMs) throws NacosException

Request parameters

Name
Type
Description
dataId
string
Configuration ID. Use a naming rule similar to package.class (for example, com.taobao.tc.refund.log.level) to ensure global uniqueness. It is recommended to indicate business meaning of the configuration in the "class" section. Use lower case for all characters. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 256 characters are allowed.
group
string
Configuration group. To ensure uniqueness, format such as product name: module name (for example, Nacos:Test) is preferred. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 128 characters are allowed.
timeout
long
Length of configuration read time-out (in ms). Recommended value: 3000.

Return values

Type Description
string configuration value

Request example

try {
    // Initialize the configuration service, and the console automatically obtains the following parameters through the sample code.
	String serverAddr = "{serverAddr}";
	String dataId = "{dataId}";
	String group = "{group}";
	Properties properties = new Properties();
	properties.put("serverAddr", serverAddr);
	ConfigService configService = NacosFactory.createConfigService(properties);
    // Actively get the configuration.
	String content = configService.getConfig(dataId, group, 5000);
	System.out.println(content);
} catch (NacosException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Exception specification

A ConfigException is thrown in case of a configuration read time-out or a network error.

Listen configuration

Description

Use dynamic configuration listening API to enable Nacos to send configuration change notifications.

public void addListener(String dataId, ConfigChangeListenerAdapter listener)

Request parameters

Name
Type
Description
dataId
string
Configuration ID. Use a naming rule similar to package.class (for example, com.taobao.tc.refund.log.level) to ensure global uniqueness. It is recommended to indicate business meaning of the configuration in the "class" section. Use lower case for all characters. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 256 characters are allowed.
group
string
Configuration group. To ensure uniqueness, format such as product name: module name (for example, Nacos:Test) is preferred. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 128 characters are allowed.
listener
Config Change Listener
Listener. Configuration changes go into the callback function of the listener.

Return values

Type Description
string Configuration value. This value is returned through the callback function during initialization or configuration modification.

Request example

// Initialize the configuration service, and the console automatically obtains the following parameters through the sample code.
String serverAddr = "{serverAddr}";
String dataId = "{dataId}";
String group = "{group}";
Properties properties = new Properties();
properties.put("serverAddr", serverAddr);
ConfigService configService = NacosFactory.createConfigService(properties);
String content = configService.getConfig(dataId, group, 5000);
System.out.println(content);
configService.addListener(dataId, group, new Listener() {
	@Override
	public void receiveConfigInfo(String configInfo) {
		System.out.println("receive1:" + configInfo);
	}
	@Override
	public Executor getExecutor() {
		return null;
	}
});

// Keep the main thread alive throughout the test, because the configuration subscription runs in a daemon thread, which exits once the main thread exits. The following code is not required in a real environment.
while (true) {
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

Delete Listening

Description

Cancel listen configuration. No more notification after cancellation.

public void removeListener(String dataId, String group, Listener listener)

Request parameters

Name
Type
Description
dataId
string
Configuration ID. Use a naming rule similar to package.class (for example, com.taobao.tc.refund.log.level) to ensure global uniqueness. It is recommended to indicate business meaning of the configuration in the "class" section. Use lower case for all characters. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 256 characters are allowed.
group
string
Configuration group
listener
ConfigChangeListenerAdapter
Listener. Configuration changes go into the callback function of the listener.

Request example

String serverAddr = "{serverAddr}";
String dataId = "{dataId}";
String group = "{group}";
Properties properties = new Properties();
properties.put("serverAddr", serverAddr);
ConfigService configService = NacosFactory.createConfigService(properties);
configService.removeListener(dataId, group, yourListener);

Publish configuration

Description

Publish Nacos configurations automatically to reduce the operation and maintenance cost.

Note: It uses the same publishing interface to create or modify a configuration. If the specified configuration doesn’t exist, it will create a configuration. If the specified configuration exists, it will update the configuration.

public boolean publishConfig(String dataId, String group, String content) throws NacosException;

@Since 1.4.1
public boolean publishConfig(String dataId, String group, String content, String type) throws NacosException;

Request parameters

Name Type Description
dataId string Configuration ID. Naming rule is similar to package.class (com.taobao.tc.refund.log.level) is used to ensure the global uniqueness We recommend that you define class by business meaning. All characters must be in lower case. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 256 characters are allowed.
group string Configuration group. We recommend that you use product name: module name (for example Nacos:Test) to ensure the uniqueness. Use alphabetical letters and these four special characters (".", ":", "-", "_") only. Up to 128 characters are allowed.
content string Configuration content. No more than 100K bytes.
type string @Since 1.4.1. Configuration type. See com.alibaba.nacos.api.config.ConfigType, default as TEXT.

Response parameters

Type Description
boolean If the publishing is successful

Request example

try {
    // Initialize the configuration service. Retrieves the following parameters in console with sample code
	String serverAddr = "{serverAddr}";
	String dataId = "{dataId}";
	String group = "{group}";
	Properties properties = new Properties();
	properties.put("serverAddr", serverAddr);
    ConfigService configService = NacosFactory.createConfigService(properties);
	boolean isPublishOk = configService.publishConfig(dataId, group, "content");
	System.out.println(isPublishOk);
} catch (NacosException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Exceptions

In case of reading configuration timeout or network issues, ConfigException exception is thrown.

Delete configuration

Description

It deletes Nacos configurations automatically with program to reduce operation and maintenance costs with automation.

Note: If the specified configuration exists, then it deletes the configuration. If the specified configuration doesn’t exist, then it returns a successful message.

public boolean removeConfig(String dataId, String group) throws NacosException

Request parameters

Parameter name Parameter type Description
dataId String Configuration ID
group String Configuration group

Response parameters

Parameter type Description
boolean If the deletion is successful

Request example

try {
    // Initialize the configuration service. Retrieves the following parameters in console with sample code
	String serverAddr = "{serverAddr}";
	String dataId = "{dataId}";
	String group = "{group}";
	Properties properties = new Properties();
	properties.put("serverAddr", serverAddr);

	ConfigService configService = NacosFactory.createConfigService(properties);
	boolean isRemoveOk = configService.removeConfig(dataId, group);
	System.out.println(isRemoveOk);
} catch (NacosException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Exceptions

In case of reading configuration timeout or network issues, ConfigException exception is thrown.

Service Discovery SDK

Register Instance

Description

Register an instance to service.

void registerInstance(String serviceName, String ip, int port) throws NacosException;

void registerInstance(String serviceName, String ip, int port, String clusterName) throws NacosException;

void registerInstance(String serviceName, Instance instance) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
ip String instance ip
port int instance port
clusterName String cluster name
instance Refer to Java docs instance properties

Response

void

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
naming.registerInstance("nacos.test.3", "11.11.11.11", 8888, "TEST1");

Instance instance = new Instance();
instance.setIp("55.55.55.55");
instance.setPort(9999);
instance.setHealthy(false);
instance.setWeight(2.0);
Map<String, String> instanceMeta = new HashMap<>();
instanceMeta.put("site", "et2");
instance.setMetadata(instanceMeta);

Service service = new Service("nacos.test.4");
service.setApp("nacos-naming");
service.setHealthCheckMode("server");
service.setProtectThreshold(0.8F);
service.setGroup("CNCF");
Map<String, String> serviceMeta = new HashMap<>();
serviceMeta.put("symmetricCall", "true");
service.setMetadata(serviceMeta);
instance.setService(service);

Cluster cluster = new Cluster();
cluster.setName("TEST5");
AbstractHealthChecker.Http healthChecker = new AbstractHealthChecker.Http();
healthChecker.setExpectedResponseCode(400);
healthChecker.setCurlHost("USer-Agent|Nacos");
healthChecker.setCurlPath("/xxx.html");
cluster.setHealthChecker(healthChecker);
Map<String, String> clusterMeta = new HashMap<>();
clusterMeta.put("xxx", "yyyy");
cluster.setMetadata(clusterMeta);

instance.setCluster(cluster);

naming.registerInstance("nacos.test.4", instance);

Deregister Instance

Description

Remove instance from service.

void deregisterInstance(String serviceName, String ip, int port) throws NacosException;

void deregisterInstance(String serviceName, String ip, int port, String clusterName) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
ip String instance ip
port int instance port
clusterName String cluster name

Response

None

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
naming.deregisterInstance("nacos.test.3", "11.11.11.11", 8888, "DEFAULT");

Get all instances of service

Description

Get all instances of service.

List<Instance> getAllInstances(String serviceName) throws NacosException;

List<Instance> getAllInstances(String serviceName, List<String> clusters) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
clusters List cluster list

Response

List<Instance> instance list。

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
System.out.println(naming.getAllInstances("nacos.test.3"));

Get filtered list of instance

Description

Get healthy or unhealthy instances of service.

List<Instance> selectInstances(String serviceName, boolean healthy) throws NacosException;

List<Instance> selectInstances(String serviceName, List<String> clusters, boolean healthy) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
clusters List cluster list
healthy boolean healthy or not

Response

List<Instance> instance list.

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
System.out.println(naming.selectInstances("nacos.test.3", true));

Get one healthy instance

Description

Get one healthy instance selected by load-balance strategy.

Instance selectOneHealthyInstance(String serviceName) throws NacosException;

Instance selectOneHealthyInstance(String serviceName, List<String> clusters) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
clusters List cluster list

Response

Instance

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
System.out.println(naming.selectOneHealthyInstance("nacos.test.3"));

Listen Service

Description

Listen for changes of instances under a service.

void subscribe(String serviceName, EventListener listener) throws NacosException;

void subscribe(String serviceName, List<String> clusters, EventListener listener) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
clusters List cluster list
listener EventListener event listener

Response

void

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
naming.subscribe("nacos.test.3", event -> {
    if (event instanceof NamingEvent) {
        System.out.println(((NamingEvent) event).getServceName());
        System.out.println(((NamingEvent) event).getInstances());
    }
});

Unlisten Service

Description

Cancel listening service.

void unsubscribe(String serviceName, EventListener listener) throws NacosException;

void unsubscribe(String serviceName, List<String> clusters, EventListener listener) throws NacosException;

Request Parameters

Name Type Description
serviceName String service name
clusters List cluster list
listener EventListener event listener

Response

void

Request Example

NamingService naming = NamingFactory.createNamingService(System.getProperty("serveAddr"));
naming.unsubscribe("nacos.test.3", event -> {});