小六六学Netty系列之编解码器和handler的调用机制（下）

package com.xiaoliuliu.netty.hander;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 21:22
 */
public class MyClientHandler  extends SimpleChannelInboundHandler<Long> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Long msg) throws Exception {
        System.out.println("服务器的ip=" + ctx.channel().remoteAddress());
        System.out.println("收到服务器消息=" + msg);
    }
    //重写channelActive 发送数据
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("MyClientHandler 发送数据");
        //ctx.writeAndFlush(Unpooled.copiedBuffer(""))
        ctx.writeAndFlush(123456L); //发送的是一个long
        //分析
        //1. "abcdabcdabcdabcd" 是 16个字节
        //2. 该处理器的前一个handler 是  MyLongToByteEncoder
        //3. MyLongToByteEncoder 父类  MessageToByteEncoder
        //4. 父类  MessageToByteEncoder
        /*
         public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        ByteBuf buf = null;
        try {
            if (acceptOutboundMessage(msg)) { //判断当前msg 是不是应该处理的类型，如果是就处理，不是就跳过encode
                @SuppressWarnings("unchecked")
                I cast = (I) msg;
                buf = allocateBuffer(ctx, cast, preferDirect);
                try {
                    encode(ctx, cast, buf);
                } finally {
                    ReferenceCountUtil.release(cast);
                }
                if (buf.isReadable()) {
                    ctx.write(buf, promise);
                } else {
                    buf.release();
                    ctx.write(Unpooled.EMPTY_BUFFER, promise);
                }
                buf = null;
            } else {
                ctx.write(msg, promise);
            }
        }
        4. 因此我们编写 Encoder 是要注意传入的数据类型和处理的数据类型一致
        */
        // ctx.writeAndFlush(Unpooled.copiedBuffer("abcdabcdabcdabcd",CharsetUtil.UTF_8));
    }
}
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package com.xiaoliuliu.netty.hander;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 21:18
 */
public class MyLongToByteEncoder extends MessageToByteEncoder<Long> {
    //编码方法
    @Override
    protected void encode(ChannelHandlerContext ctx, Long msg, ByteBuf out) throws Exception {
        System.out.println("MyLongToByteEncoder encode 被调用");
        System.out.println("msg=" + msg);
        out.writeLong(msg);
    }
}
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package com.xiaoliuliu.netty.hander;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;
import java.util.List;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 21:36
 */
public class MyByteToLongDecoder2 extends ReplayingDecoder<Void> {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        System.out.println("MyByteToLongDecoder2 被调用");
        //在 ReplayingDecoder 不需要判断数据是否足够读取，内部会进行处理判断
        out.add(in.readLong());
    }
}
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package com.xiaoliuliu.netty.hander;
import com.atguigu.netty.inboundhandlerandoutboundhandler.MyServerInitializer;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 20:50
 */
public class MyServer {
    public static void main(String[] args) throws Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class).childHandler(new MyServerInitializer()); //自定义一个初始化类
            ChannelFuture channelFuture = serverBootstrap.bind(7000).sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}
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package com.xiaoliuliu.netty.hander;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 20:59
 */
public class MyServerInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();//一会下断点
        //入站的handler进行解码 MyByteToLongDecoder
        pipeline.addLast(new MyByteToLongDecoder());
        //pipeline.addLast(new MyByteToLongDecoder2());
        //出站的handler进行编码
        pipeline.addLast(new MyLongToByteEncoder());
        //自定义的handler 处理业务逻辑
        pipeline.addLast(new MyServerHandler());
        System.out.println("xx");
    }
}
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package com.xiaoliuliu.netty.hander;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
 * @author 小六六
 * @version 1.0
 * @date 2020/9/1 21:19
 */
public class MyServerHandler extends SimpleChannelInboundHandler<Long> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Long msg) throws Exception {
        System.out.println("从客户端" + ctx.channel().remoteAddress() + " 读取到long " + msg);
        //给客户端发送一个long
        ctx.writeAndFlush(98765L);
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}
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