本文共 14554 字，大约阅读时间需要 48 分钟。
[toc]
程序代码来自于《Netty权威指南》第8章，已经加了注释，不过需要注意的是，使用的proto源代码是在中生成的，关于protobuf代码自动生成工具的使用可以参考这篇文章。
例子中，通过×××ProtobufVarint32FrameDecoder和编码器ProtobufVarint32LengthFieldPrepender的使用已经解决了半包问题，测试时可以把其注释掉，这样就可以演示Netty中使用Protobuf出现的TCP粘包问题。
同时，通过protobuf的使用，也可以深刻感受到，其在Netty中的使用确实非常简单，编解码、半包问题，只需要添加相关的处理器即可，而且它可以方便地实现跨语言的远程服务调用。（protobuf本身提供了对不同语言的支持）
但其实在使用时会发现有一个问题，就是编解码的对象是需要使用其生成的特定的proto对象来进行操作的，也就是说，需要编写.proto文件，再通过protoc来生成相应语言的代码文件，显然这样做还是会有些麻烦（虽然其实也还好，不算麻烦），有没有方便点的方法呢？后面通过protostuff的使用即可解决这个问题。
package cn.xpleaf.subscribe;import cn.xpleaf.protobuf.SubscribeReqProto;import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;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.logging.LogLevel;import io.netty.handler.logging.LoggingHandler;public class SubReqServer { public void bind(int port) throws Exception { // 配置服务端的NIO线程组 EventLoopGroup bossGroup = new NioEventLoopGroup(); EventLoopGroup workerGroup = new NioEventLoopGroup(); try { ServerBootstrap b = new ServerBootstrap(); b.group(bossGroup, workerGroup) .channel(NioServerSocketChannel.class) .option(ChannelOption.SO_BACKLOG, 1024) // 添加日志处理器 .handler(new LoggingHandler(LogLevel.INFO)) .childHandler(new ChannelInitializer () { @Override protected void initChannel(SocketChannel ch) throws Exception { // 添加ProtobufVarint32FrameDecoder，主要用于Protobuf的半包处理 ch.pipeline().addLast(new ProtobufVarint32FrameDecoder()); // 添加ProtobufDecoder×××，它的参数是com.google.protobuf.MessageLite // 实际上就是要告诉ProtobufDecoder需要解码的目标类是什么，否则仅仅从字节数组中是 // 无法判断出要解码的目标类型信息的（服务端需要解析的是客户端请求，所以是Req） ch.pipeline().addLast(new ProtobufDecoder(SubscribeReqProto.SubscribeReq.getDefaultInstance())); /** * 来自源码的代码注释，用于Protobuf的半包处理 * * An encoder that prepends the the Google Protocol Buffers * Base * 128 Varints integer length field. For example: * * BEFORE ENCODE (300 bytes) AFTER ENCODE (302 bytes) * +---------------+ +--------+---------------+ * | Protobuf Data |-------------->| Length | Protobuf Data | * | (300 bytes) | | 0xAC02 | (300 bytes) | * +---------------+ +--------+---------------+ *
* */ ch.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender()); // 添加ProtobufEncoder编码器，这样就不需要对SubscribeResp进行手工编码 ch.pipeline().addLast(new ProtobufEncoder()); // 添加业务处理handler ch.pipeline().addLast(new SubReqServerHandler()); } }); // 绑定端口，同步等待成功 ChannelFuture f = b.bind(port).sync(); // 等待服务端监听端口关闭 f.channel().closeFuture().sync(); } finally { // 优雅退出，释放线程池资源 bossGroup.shutdownGracefully(); workerGroup.shutdownGracefully(); } } public static void main(String[] args) throws Exception { int port = 8080; if(args != null && args.length > 0) { try { port = Integer.valueOf(port); } catch (NumberFormatException e) { // TODO: handle exception } } new SubReqServer().bind(port); }} package cn.xpleaf.subscribe;import cn.xpleaf.protobuf.SubscribeReqProto;import cn.xpleaf.protobuf.SubscribeRespProto;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;public class SubReqServerHandler extends ChannelInboundHandlerAdapter { /** * 由于ProtobufDecoder已经对消息进行了自动解码，因此接收到的订购请求消息可以直接使用 * 对用户名进行校验，校验通过后构造应答消息返回给客户端，由于使用了ProtobufEncoder， * 所以不需要对SubscribeRespProto.SubscribeResp进行手工编码 */ @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { SubscribeReqProto.SubscribeReq req = (SubscribeReqProto.SubscribeReq)msg; String username = req.getUserName(); if("xpleaf".equalsIgnoreCase(username)) { System.out.println("Service accept client subscribe req : [" + req.toString() + "]"); ctx.writeAndFlush(resp(req.getSubReqID())); } } /** * 构建SubscribeRespProto.SubscribeResp对象 * @param subReqID * @return */ private SubscribeRespProto.SubscribeResp resp(int subReqID) { SubscribeRespProto.SubscribeResp.Builder builder = SubscribeRespProto.SubscribeResp.newBuilder(); builder.setSubReqID(subReqID); builder.setRespCode(0); builder.setDesc("Netty book order succeed, 3 days later, sent to the designated address"); return builder.build(); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // 发生异常，关闭链路 ctx.close(); }} package cn.xpleaf.subscribe;import cn.xpleaf.protobuf.SubscribeRespProto;import io.netty.bootstrap.Bootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;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.logging.LogLevel;import io.netty.handler.logging.LoggingHandler;public class SubReqClient { public void connect(String host, int port) throws Exception { // 配置客户端NIO线程组 EventLoopGroup group = new NioEventLoopGroup(); try { Bootstrap b = new Bootstrap(); b.group(group).channel(NioSocketChannel.class) .option(ChannelOption.TCP_NODELAY, true) // 设置TCP连接超时时间 .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000) .handler(new ChannelInitializer () { @Override protected void initChannel(SocketChannel ch) throws Exception { // 添加ProtobufVarint32FrameDecoder，主要用于Protobuf的半包处理 ch.pipeline().addLast(new ProtobufVarint32FrameDecoder()); // 添加ProtobufDecoder×××，它的参数是com.google.protobuf.MessageLite // 实际上就是要告诉ProtobufDecoder需要解码的目标类是什么，否则仅仅从字节数组中是 // 无法判断出要解码的目标类型信息的（客户端需要解析的是服务端请求，所以是Resp） ch.pipeline().addLast(new ProtobufDecoder(SubscribeRespProto.SubscribeResp.getDefaultInstance())); /** * 来自源码的代码注释，用于Protobuf的半包处理 * * An encoder that prepends the the Google Protocol Buffers * Base * 128 Varints integer length field. For example: * * BEFORE ENCODE (300 bytes) AFTER ENCODE (302 bytes) * +---------------+ +--------+---------------+ * | Protobuf Data |-------------->| Length | Protobuf Data | * | (300 bytes) | | 0xAC02 | (300 bytes) | * +---------------+ +--------+---------------+ *
* */ ch.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender()); // 添加ProtobufEncoder编码器，这样就不需要对SubscribeResp进行手工编码 ch.pipeline().addLast(new ProtobufEncoder()); // 添加业务处理handler ch.pipeline().addLast(new SubReqClientHandler()); } }); // 发起异步连接操作 ChannelFuture f = b.connect(host, port).sync(); // 等待客户端链路关闭 f.channel().closeFuture().sync(); } finally { // 优雅退出，释放NIO线程组 group.shutdownGracefully(); } } public static void main(String[] args) throws Exception { int port = 8080; if(args != null && args.length > 0) { try { port = Integer.valueOf(port); } catch (NumberFormatException e) { // 采用默认值 } } new SubReqClient().connect("localhost", port); }} package cn.xpleaf.subscribe;import java.util.ArrayList;import java.util.List;import cn.xpleaf.protobuf.SubscribeReqProto;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;public class SubReqClientHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) { for(int i = 0; i < 10; i++) { ctx.write(subReq(i)); } ctx.flush(); } /** * 构建SubscribeReqProto.SubscribeReq对象 * @param i * @return */ private SubscribeReqProto.SubscribeReq subReq(int i) { SubscribeReqProto.SubscribeReq.Builder builder = SubscribeReqProto.SubscribeReq.newBuilder(); builder.setSubReqID(i); builder.setUserName("xpleaf"); builder.setProductName("Netty Book For Protobuf"); List address = new ArrayList<>(); address.add("NanJing YuHuaTai"); address.add("BeiJing LiuLiChange"); address.add("ShenZhen HongShuLin"); builder.addAllAddress(address); return builder.build(); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { System.out.println("Service accept server subscribe response : [" + msg + "]"); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); }} 服务端输出如下：
Service accept client subscribe req : [subReqID: 0userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 1userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 2userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 3userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 4userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 5userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 6userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 7userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 8userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]Service accept client subscribe req : [subReqID: 9userName: "xpleaf"productName: "Netty Book For Protobuf"address: "NanJing YuHuaTai"address: "BeiJing LiuLiChange"address: "ShenZhen HongShuLin"]
客户端输出如下：
Service accept server subscribe response : [subReqID: 0respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 1respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 2respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 3respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 4respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 5respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 6respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 7respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 8respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]Service accept server subscribe response : [subReqID: 9respCode: 0desc: "Netty book order succeed, 3 days later, sent to the designated address"]
转载于:https://blog.51cto.com/xpleaf/2071715