Nacos 服务状态监听四种写发

监听服务的四种实现方式，以监听 Nacos 服务为例

1. 传统方式

public void subscribe() {
    try {

            NamingService namingService = NamingFactory.createNamingService("127.0.0.1:8848");
            namingService.subscribe("serverName","groupName",new EventListener() {
                @Override
                public void onEvent(Event event) {
                   if (event instanceof NamingEvent) {
                        System.out.println("服务名："+((NamingEvent)event).getServiceName());
                        System.out.println("实例："+((NamingEvent)event).getInstances());
                    }
                }
            });

    } catch (NacosException e) {
        logger.error(e.getMessage(), e);
    }
} 

2. 简写方式

public void subscribe() {
    try {

            NamingService namingService = NamingFactory.createNamingService("127.0.0.1:8848");
            namingService.subscribe("serverName","groupName", event -> {
                if (event instanceof NamingEvent) {
                    System.out.println("服务名："+((NamingEvent)event).getServiceName());
                    System.out.println("实例："+((NamingEvent)event).getInstances());
                }
            });

    } catch (NacosException e) {
        logger.error(e.getMessage(), e);
    }
} 

3. 独立方法

public void subscribe() {
    try {

            NamingService namingService = NamingFactory.createNamingService("127.0.0.1:8848");
            namingService.subscribe("serverName","groupName", serviceListener);

    } catch (NacosException e) {
        logger.error(e.getMessage(), e);
    }
} 

EventListener serviceListener = (event) ->
{
    if (event instanceof NamingEvent) {
        System.out.println("服务名："+((NamingEvent)event).getServiceName());
        System.out.println("实例："+((NamingEvent)event).getInstances());
    }
};

4. 独立文件

public void subscribe() {
    try {

            NamingService namingService = NamingFactory.createNamingService("127.0.0.1:8848");
            namingService.subscribe("serverName","groupName", new NacosListener());

    } catch (NacosException e) {
        logger.error(e.getMessage(), e);
    }
} 

//单独Class类
public class NacosListener implements EventListener {
    @Override
    public void onEvent(Event event) {
        if (event instanceof NamingEvent) {
            System.out.println(((NamingEvent)event).getServiceName());
            System.out.println(((NamingEvent)event).getInstances());
        }
    }
}