玄学springboot applicationcontext.getBean(用类名String还是类型Class), getBean(..)的调用场景结果不同？getBean(..)还会阻塞？@DependsOn按照名称依赖，那么getBean用类名String

springContextStati是一个实现了Applicationcontextaware的类的名字，可以getBean(..)RegistryTask是一个在RegistryServer调用netty封装的channelinitializer时候，的clienthandler被触发读事件的时候 new 的

@Component
@DependsOn(value={"springContextStatic","normalConfig","channelCache","serviceAddrCache"})DependsOn的参数都是String字符串，类的名称，后面在RegistryTask的构造函数中，必须用appcontext.getBean(String name)获得bean,否则阻塞。
public class RegistryServer {
    .....
......
    @PostConstruct
    private void doRunServer() {
            try {            此处被注释的代码部分如果不执行，那么后面一个RegistryTask阻塞在构造函数上    　　　　执行此处getBean(Class<T>)代码的意义是什么？加载？玄。。
                /*LOGGER.info("doRunServer:appctx:{}",SpringContextStatic.getApplicationContext());
                LOGGER.info("normalconfig:{}",SpringContextStatic.getBean(NormalConfig.class));
                LOGGER.info("channelcache:{}",SpringContextStatic.getBean(ChannelCache.class));
                LOGGER.info("serviceaddrcache:{}",SpringContextStatic.getBean(ServiceAddrCache.class));*/
                //创建并初始化 Netty 服务端辅助启动对象 ServerBootstrap
                ServerBootstrap serverBootstrap = initServerBootstrap(bossGroup, workerGroup);
                //绑定对应ip和端口，同步等待成功
                ChannelFuture future = serverBootstrap.bind(paramConfig.getServerport()).sync();
                LOGGER.info("regist server 已启动，端口：{}", paramConfig.getServerport());
                //等待服务端监听端口关闭
                future.channel().closeFuture().sync();
            } catch (InterruptedException i) {
                LOGGER.error("regist server 出现异常，端口：{}, cause:", paramConfig.getServerport(), i.getMessage());
            } finally {
                //优雅退出，释放 NIO 线程组
                workerGroup.shutdownGracefully();
                bossGroup.shutdownGracefully();
            }

    }

    /**
     * 创建并初始化 Netty 服务端辅助启动对象 ServerBootstrap
     *
     * @param bossGroup
     * @param workerGroup
     * @return
     */
    private ServerBootstrap initServerBootstrap(EventLoopGroup bossGroup, EventLoopGroup workerGroup) {
        return new ServerBootstrap()
                .group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, 1024)
                .childOption(ChannelOption.SO_KEEPALIVE, true)
                .childHandler(new ServerChannelInitializer(new RegistryServerHandler(threadPool)));
    }
}

public class RegistryTask implements Runnable {
    private static Logger log = LoggerFactory.getLogger(RegistryTask.class);

    private ChannelHandlerContext ctx;
    private RegistryMessage msg;
    private ChannelCache channelCache = null;
    private ServiceAddrCache serviceAddrCache = null;
    private NormalConfig normalConfig = null;

    /*private ChannelCache channelCache = SpringContextStatic.getBean(ChannelCache.class);

    private ServiceAddrCache serviceAddrCache = SpringContextStatic.getBean(ServiceAddrCache.class);

    private NormalConfig normalConfig = SpringContextStatic.getBean(NormalConfig.class);*/

    public RegistryTask(ChannelHandlerContext ctx, RegistryMessage msg) {
        System.out.println("constructing registrytask,appctx:"+SpringContextStatic.getApplicationContext());
        log.info("doRunServer:appctx:{}",SpringContextStatic.getApplicationContext());
        log.info("normalconfig:{}",SpringContextStatic.getBean("normalConfig"));
        /*log.info("channelcache:{}",SpringContextStatic.getBean(ChannelCache.class));
        log.info("serviceaddrcache:{}",SpringContextStatic.getBean(ServiceAddrCache.class));*/

        this.ctx = ctx;
        this.msg = msg;

      上一个文件的被注释部分getBean(Class<T>)如果不执行，此处会阻塞,why?
        /*this.channelCache = SpringContextStatic.getBean(ChannelCache.class);
        this.serviceAddrCache = SpringContextStatic.getBean(ServiceAddrCache.class);
        this.normalConfig = SpringContextStatic.getBean(NormalConfig.class);*/
        正确写法：getBean(String name)
        this.channelCache = (ChannelCache) SpringContextStatic.getBean("channelCache");
        this.serviceAddrCache = (ServiceAddrCache) SpringContextStatic.getBean("serviceAddrCache");
        this.normalConfig = (NormalConfig) SpringContextStatic.getBean("normalConfig");
    }

原文地址：https://www.cnblogs.com/CreatorKou/p/11354682.html