SimpleChannelInboundHandler 中常用的事件方法

﹏ヽ暗。殇╰゛Y 2022-09-06 00:27 279阅读 0赞

从建立连接到断开连接，会触发各种事件，每个事件的触发都会关联处理器中的某个方法被调用。

从建立连接到断开连接会依次执行下列方法：

<table style="width:500px;"> 
 <tbody> 
  <tr> 
   <td>事件</td> 
   <td>方法</td> 
  </tr> 
  <tr> 
   <td> <pre><code>新的客户端连接事件</code></pre> </td> 
   <td> <pre><code>handlerAdded</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道注册事件</code></pre> </td> 
   <td> <pre><code>channelRegistered</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道处于活动状态事件</code></pre> </td> 
   <td> <pre><code>channelActive</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道数据可读取事件</code></pre> </td> 
   <td> <pre><code>channelRead0</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道数据读取完毕事件</code></pre> </td> 
   <td> <pre><code>channelReadComplete</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道进入非活动状态事件</code></pre> </td> 
   <td> <pre><code>channelInactive</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>通道移除事件</code></pre> </td> 
   <td> <pre><code>channelUnregistered</code></pre> </td> 
  </tr> 
  <tr> 
   <td> <pre><code>处理器移除事件(断开连接)</code></pre> </td> 
   <td> <pre><code>handlerRemoved</code></pre> </td> 
  </tr> 
  <tr> 
   <td>异常发生事件</td> 
   <td> <pre>exceptionCaught</pre> </td> 
  </tr> 
 </tbody> 
</table>

数据可读取事件和数据读取完毕事件，会随着多次请求进行数据传输，而被多次调用执行。

如下实现一个服务端接收http请求的功能，进行调用执行结果测试这些方法：

package com.tech.netty.netty.handlertest;
    
    import io.netty.bootstrap.ServerBootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    
    /**
     * @author lw
     * @since 2021/8/17
     */
    public class TestServer {
        public static void main(String[] args) throws InterruptedException {
    
            NioEventLoopGroup bossGroup = new NioEventLoopGroup(1);
            NioEventLoopGroup workerGroup = new NioEventLoopGroup();
            try{
                ServerBootstrap serverBootstrap = new ServerBootstrap();
                serverBootstrap.group(bossGroup,workerGroup)
                        .channel(NioServerSocketChannel.class)
                        .childHandler(new TestServerInitializer());
                ChannelFuture channelFuture = serverBootstrap.bind(7000).sync();
                channelFuture.channel().closeFuture().sync();
            }finally {
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        }
    }

package com.tech.netty.netty.handlertest;
    
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.handler.codec.http.HttpServerCodec;
    
    /**
     * @author lw
     * @since 2021/8/17
     */
    public class TestServerInitializer extends ChannelInitializer<SocketChannel> {
        @Override
        protected void initChannel(SocketChannel socketChannel) throws Exception {
            // HttpServerCodec 是Netty提供的编解码器
            socketChannel.pipeline().addLast("MyHttpServerCodec",new HttpServerCodec())
                    .addLast("",new TestServerHandler()); //在管道添加一个自定义处理器
        }
    }

package com.tech.netty.netty.handlertest;
    
    import io.netty.buffer.ByteBuf;
    import io.netty.buffer.Unpooled;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.SimpleChannelInboundHandler;
    import io.netty.handler.codec.http.*;
    import io.netty.util.CharsetUtil;
    import lombok.extern.slf4j.Slf4j;
    
    /**
     * SimpleChannelInboundHandler 是 ChannelInboundHandlerAdapter
     * 客户端与服务端相互通信的数据被封装成 HttpObject
     * @author lw
     * @since 2021/8/17
     */
    @Slf4j
    public class TestServerHandler extends SimpleChannelInboundHandler<HttpObject> {
    
        /**
         * 新的客户端连接事件
         * @param ctx
         * @throws Exception
         */
        @Override
        public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
            log.info("handlerAdded 新的客户端连接事件 | channel={} remote={} ",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 通道注册事件
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
            log.info("channelRegistered 通道注册事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 通道处于活动状态事件
         * 通道完成注册后触发
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            log.info("channelActive 通道处于活动状态事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 通道数据可读取事件
         * @param ctx
         * @param msg
         * @throws Exception
         */
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
            //判断msg是不是HttpRequest请求
            if(msg instanceof HttpRequest){
                log.info("channelRead0 通道数据可读取事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
                ByteBuf content = Unpooled.copiedBuffer("hello 这里是服务器", CharsetUtil.UTF_8);
                //构造http响应
                DefaultFullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);
                response.headers().add(HttpHeaderNames.CONTENT_TYPE,"text/plain;charset=utf-8");
                response.headers().add(HttpHeaderNames.CONTENT_LENGTH,content.readableBytes());
                //将构建好response返回
                ctx.writeAndFlush(response);
            }else{
                log.info("channelRead0 通道数据可读取事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
            }
        }
    
        /**
         * 通道数据读取完毕事件
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
            log.info("channelReadComplete 通道数据读取完毕事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 通道进入非活动状态事件
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception {
            log.info("channelInactive 通道进入非活动状态事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 通道移除事件
         * @param ctx
         * @throws Exception
         */
        @Override
        public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
            log.info("channelUnregistered 通道移除事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 处理器移除事件 (断开连接)
         * @param ctx
         * @throws Exception
         */
        @Override
        public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
            log.info("handlerRemoved 处理器移除事件 | channel={} remote={}",ctx.channel().id(),ctx.channel().remoteAddress());
        }
    
        /**
         * 异常发生事件
         * @param ctx
         * @param cause
         * @throws Exception
         */
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            ctx.close();
        }
    }

14:55:41.734 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - handlerAdded 新的客户端连接事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760 
    14:55:41.734 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - handlerAdded 新的客户端连接事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761 
    14:55:41.740 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelRegistered 通道注册事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761
    14:55:41.740 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelRegistered 通道注册事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.741 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelActive 通道处于活动状态事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761
    14:55:41.741 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelActive 通道处于活动状态事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.744 [nioEventLoopGroup-3-2] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxCapacityPerThread: 32768
    14:55:41.744 [nioEventLoopGroup-3-2] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.maxSharedCapacityFactor: 2
    14:55:41.745 [nioEventLoopGroup-3-2] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.linkCapacity: 16
    14:55:41.745 [nioEventLoopGroup-3-2] DEBUG io.netty.util.Recycler - -Dio.netty.recycler.ratio: 8
    14:55:41.751 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelReadComplete 通道数据读取完毕事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.752 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelInactive 通道进入非活动状态事件(断开连接) | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.752 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelUnregistered 通道移除事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.752 [nioEventLoopGroup-3-1] INFO com.tech.netty.netty.handlertest.TestServerHandler - handlerRemoved 处理器移除事件 | channel=4f3cf93b remote=/0:0:0:0:0:0:0:1:58760
    14:55:41.766 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelRead0 通道数据可读取事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761
    14:55:41.772 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelRead0 通道数据可读取事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761
    14:55:41.772 [nioEventLoopGroup-3-2] INFO com.tech.netty.netty.handlertest.TestServerHandler - channelReadComplete 通道数据读取完毕事件 | channel=68fb840f remote=/0:0:0:0:0:0:0:1:58761