netty4 tcp与protobuf3的整合使用。

netty是一个非常棒的NIO框架就不介绍了。protobuf是google提供的一个开源序列化框架，也是一个非常棒的东西。这里不介绍这两个框架了，想要了解的朋友网上一搜一大把。

本文主要介绍 protobuf3与netty4 在tcp协议里的整合使用。个人认为netty与protobuf是绝配的组合。配合使用非常棒，框架提供了粘包拆包等工具类。特别是你要实现如及时通讯功能的时候，能让你省很多功夫。

使用protobuf需要事先预编译，这个过程这里就不介绍了，我的博客里面有，需要的可以看看。

首先在java中使用netty与protobuf需要两个jar包，我这里是：netty-all-4.1.0.CR7.jar、protobuf-java-3.1.0.jar（可以到maven下载，版本可以不同）

直接来看看代码吧。都有详细的注释：

package com.im.socket.netty.tcp;import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelId;import io.netty.channel.ChannelOption;import io.netty.channel.EventLoopGroup;import io.netty.channel.group.ChannelGroup;import io.netty.channel.group.DefaultChannelGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.util.concurrent.GlobalEventExecutor;import java.util.concurrent.ConcurrentMap;import org.jboss.netty.util.internal.ConcurrentHashMap;/** * 建立TCP netty服务 *  * @author kokJuis * @version 1.0 * @date 2016-9-30 */public class ChatServer {// 实例一个连接容器保存连接public static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);// 再搞个map保存与用户的映射关系public static ConcurrentMap<Integer, ChannelId> userSocketMap = new ConcurrentHashMap<Integer, ChannelId>();private int port;public ChatServer(int port) {this.port = port;}public void run() throws Exception {EventLoopGroup bossGroup = new NioEventLoopGroup();// boss线程池EventLoopGroup workerGroup = new NioEventLoopGroup();// worker线程池try {ServerBootstrap b = new ServerBootstrap();b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)// 使用TCP.childHandler(new ChatServerInitializer())// 初始化配置的处理器.option(ChannelOption.SO_BACKLOG, 128)// BACKLOG用于构造服务端套接字ServerSocket对象，标识当服务器请求处理线程全满时，用于临时存放已完成三次握手的请求的队列的最大长度。如果未设置或所设置的值小于1，Java将使用默认值50。.childOption(ChannelOption.SO_KEEPALIVE, true);// 是否启用心跳保活机制。在双方TCP套接字建立连接后（即都进入ESTABLISHED状态）并且在两个小时左右上层没有任何数据传输的情况下，这套机制才会被激活。System.out.println("[ChatServer 启动了]");// 绑定端口，开始接收进来的连接ChannelFuture f = b.bind(port).sync();// 等待服务器 socket 关闭 。// 这不会发生，可以优雅地关闭服务器。f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();bossGroup.shutdownGracefully();System.out.println("[ChatServer 关闭了]");}}}

package com.im.socket.netty.tcp;import java.util.concurrent.TimeUnit;import com.im.socket.protobuf.MessageOuterClass.Message;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.socket.SocketChannel;import io.netty.handler.codec.DelimiterBasedFrameDecoder;import io.netty.handler.codec.Delimiters;import io.netty.handler.codec.protobuf.ProtobufDecoder;import io.netty.handler.codec.protobuf.ProtobufEncoder;import io.netty.handler.codec.protobuf.ProtobufVarint32FrameDecoder;import io.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender;import io.netty.handler.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;import io.netty.handler.timeout.IdleStateHandler;import io.netty.util.CharsetUtil;import io.netty.util.HashedWheelTimer;import io.netty.util.Timer;/** * netty处理器配置 *  * @author kokJuis * @version 1.0 * @date 2016-9-30 */public class ChatServerInitializer extends ChannelInitializer<SocketChannel> {Timer timer;public ChatServerInitializer() {timer = new HashedWheelTimer();}@Overridepublic void initChannel(SocketChannel ch) throws Exception {ChannelPipeline pipeline = ch.pipeline();// ----Protobuf处理器，这里的配置是关键----pipeline.addLast("frameDecoder", new ProtobufVarint32FrameDecoder());// 用于decode前解决半包和粘包问题（利用包头中的包含数组长度来识别半包粘包）//配置Protobuf解码处理器，消息接收到了就会自动解码，ProtobufDecoder是netty自带的，Message是自己定义的Protobuf类pipeline.addLast("protobufDecoder",new ProtobufDecoder(Message.getDefaultInstance()));// 用于在序列化的字节数组前加上一个简单的包头，只包含序列化的字节长度。pipeline.addLast("frameEncoder",new ProtobufVarint32LengthFieldPrepender());//配置Protobuf编码器，发送的消息会先经过编码pipeline.addLast("protobufEncoder", new ProtobufEncoder());// ----Protobuf处理器END----pipeline.addLast("handler", new ChatServerHandler());//自己定义的消息处理器，接收消息会在这个类处理pipeline.addLast("ackHandler", new AckServerHandler());//处理ACKpipeline.addLast("timeout", new IdleStateHandler(100, 0, 0,TimeUnit.SECONDS));// //此两项为添加心跳机制,60秒查看一次在线的客户端channel是否空闲pipeline.addLast(new HeartBeatServerHandler());// 心跳处理handler}// pipeline.addLast("framer", new DelimiterBasedFrameDecoder(// 2 * 1024, Delimiters.lineDelimiter()));// pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));// pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));}

package com.im.socket.netty.tcp;import java.util.Map.Entry;import com.im.socket.enums.EnumMessageType;import com.im.socket.protobuf.MessageOuterClass.Message;import io.netty.channel.Channel;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelId;import io.netty.channel.SimpleChannelInboundHandler;/** * 消息处理类 *  * @author kokJuis * @version 1.0 * @date 2016-9-30 */public class ChatServerHandler extends SimpleChannelInboundHandler<Message> {@Overridepublic void handlerAdded(ChannelHandlerContext ctx) throws Exception {Channel incoming = ctx.channel();System.out.println("[SERVER] - " + incoming.remoteAddress() + " 连接过来\n");}@Overridepublic void handlerRemoved(ChannelHandlerContext ctx) throws Exception {Channel incoming = ctx.channel();ChatServer.channels.remove(incoming);System.out.println("[SERVER] - " + incoming.remoteAddress() + " 离开\n");// A closed Channel is automatically removed from ChannelGroup,// so there is no need to do "channels.remove(ctx.channel());"}@Overrideprotected void channelRead0(ChannelHandlerContext ctx, Message msg)throws Exception {//消息会在这个方法接收到，msg就是经过解码器解码后得到的消息，框架自动帮你做好了粘包拆包和解码的工作//处理消息逻辑ctx.fireChannelRead(msg);//把消息交给下一个处理器}@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception { // (5)Channel incoming = ctx.channel();System.out.println("ChatClient:" + incoming.remoteAddress() + "上线");}@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception { // (6)Channel incoming = ctx.channel();System.out.println("ChatClient:" + incoming.remoteAddress() + "掉线");}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // (7)Channel incoming = ctx.channel();// 当出现异常就关闭连接System.out.println("ChatClient:" + incoming.remoteAddress()+ "异常,已被服务器关闭");cause.printStackTrace();ctx.close();}}

package com.im.socket.netty.tcp;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;import io.netty.handler.timeout.IdleState;import io.netty.handler.timeout.IdleStateEvent;/** * 心跳检测 *  * @ClassName HeartBeatServerHandler * @Description TODO * @author kokjuis [e-mail] * @date 2016-9-26 * @content */public class HeartBeatServerHandler extends ChannelInboundHandlerAdapter {private int loss_connect_time = 0;@Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt)throws Exception {if (evt instanceof IdleStateEvent) {IdleStateEvent event = (IdleStateEvent) evt;if (event.state() == IdleState.READER_IDLE) {loss_connect_time++;System.out.println("[60 秒没有接收到客户端" + ctx.channel().id()+ "的信息了]");if (loss_connect_time > 2) {// 超过20秒没有心跳就关闭这个连接System.out.println("[关闭这个不活跃的channel:" + ctx.channel().id()+ "]");ctx.channel().close();}}} else {super.userEventTriggered(ctx, evt);}}}