使用Spring+Netty的UDP服务器

Question

我试图使用Netty来设置一个简单的UDP服务器，遵循这里的示例，但使用Spring来连接依赖项。

我的Spring配置类：

@Configuration
@ComponentScan("com.example.netty")
public class SpringConfig {

    @Value("${netty.nThreads}")
    private int nThreads;

    @Autowired
    private MyHandlerA myHandlerA;

    @Autowired
    private MyHandlerB myHandlerB;

    @Bean(name = "bootstrap")
    public Bootstrap bootstrap() {
        Bootstrap b = new Bootstrap();
        b.group(group())
                .channel(NioDatagramChannel.class)
                .handler(new ChannelInitializer<DatagramChannel>() {
                    @Override
                    protected void initChannel(DatagramChannel ch) throws Exception {
                        ch.pipeline().addLast(myHandlerA, myHandlerB);
                    }
                });
        return b;
    }

    @Bean(name = "group", destroyMethod = "shutdownGracefully")
    public NioEventLoopGroup group() {
        return new NioEventLoopGroup(nThreads);
    }

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

}

@Component
public class MyUDPServer {

    @Autowired
    private Bootstrap bootstrap;

    @Value("${host}")
    private String host;

    @Value("${port}")
    private int port;

    @PostConstruct
    public void start() throws Exception {
        bootstrap.bind(host, port).sync().channel().closeFuture().await();
        /* Never reached since the main thread blocks due to the call to await() */
    }
}

为了避免阻塞主线程（用于Spring配置），我创建了一个新线程，如下所示：

@Component
public class MyUDPServer extends Thread {

    @Autowired
    private Bootstrap bootstrap;

    @Value("${host}")
    private String host;

    @Value("${port}")
    private int port;

    public MyUDPServer() {
        setName("UDP Server");
    }

    @PostConstruct
    @Override
    public synchronized void start() {
        super.start();
    }

    @Override
    public void run() {
        try {
            bootstrap.bind(host, port).sync().channel().closeFuture().await();
        } catch (InterruptedException e) {

        } finally {
            bootstrap.group().shutdownGracefully();
        }
    }

    @PreDestroy
    @Override
    public void interrupt() {
        super.interrupt();
    }
}

我可以看到新线程被阻塞，等待通道关闭（如示例所示）。主线程可以继续Spring配置。然而，这仍然不起作用。

Answer 1

不需要在@postconstruct中等待通道的终止。尝试删除await()。