Springboot中启动netty的两种方式

在SpringBoot中启动Netty

方式1

1. 设置一个ApplicationListener

   @Component
   public class NettyBooter implements ApplicationListener<ContextRefreshedEvent>{
   
   	@Override
   	public void onApplicationEvent(ContextRefreshedEvent event) {
   		if(event.getApplicationContext().getParent()==null) {
   			try {
   				NettyServer.getInstance().start();
   			} catch (Exception e) {
   				e.printStackTrace();
   			}
   		}
   	}
   }
   

2. NettyServer

   @Component
   public class NettyServer {
       private static class SingletonNettyServer{
           static final NettyServer instance = new NettyServer();
       }
   
       private EventLoopGroup mainGroup;
       private EventLoopGroup subGroup;
       private ServerBootstrap serverBootstrap;
       private ChannelFuture future;
   
       public static NettyServer getInstance() {
           return SingletonNettyServer.instance;
       }
   
       public NettyServer(){
           mainGroup = new NioEventLoopGroup();
           subGroup = new NioEventLoopGroup();
           serverBootstrap = new ServerBootstrap();
           serverBootstrap.group(mainGroup, subGroup)
               .channel(NioServerSocketChannel.class)
               .childHandler(new NettyServerInitializer());
       }
   
       public void start(){
           this.future = serverBootstrap.bind(9999);
           System.err.println("netty 服务启动成功");
       }
   }
   

方式2

使用注解@PostConstruct启动

参考文章

@Component大家都能熟悉了，就是把普通pojo实例化到spring容器中，相当于配置文件中的。泛指各种组件，比如类不属于@Controller或者@Service等时，就可以用该注解标注；

@PostConstruct这个注解是我第一次接触，在方法上加该注解会在项目启动的时候执行该方法，即spring容器初始化的时候执行，它与构造函数及@Autowired的执行顺序为：构造函数 >> @Autowired >> @PostConstruct，由此看来当我们想在生成对象时完成某些初始化操作，而偏偏这些初始化操作又依赖于注入的bean，那么就无法在构造函数中实现，为此可以使用@PostConstruct注解一个init方法来完成初始化，该方法会在bean注入完成后被自动调用。

@Component
public class NettyServer {
    private EventLoopGroup mainGroup;
    private EventLoopGroup subGroup;
    private ServerBootstrap serverBootstrap;
    private ChannelFuture future;

    public NettyServer(){
        mainGroup = new NioEventLoopGroup();
        subGroup = new NioEventLoopGroup();
        serverBootstrap = new ServerBootstrap();
        serverBootstrap.group(mainGroup, subGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new NettyServerInitializer());
    }

    @PostConstruct
    public void start(){
        this.future = serverBootstrap.bind(9999);
        System.err.println("netty 服务启动成功");
    }
}