Google Protobuf在Netty中的使用

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Google Protobuf在Netty中的使用

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Google Protobuf入门与使用中生成的，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，通过解码器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。

服务端

SubReqServer.java

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<SocketChannel>() {                    @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解码器，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                         * <a href="https://developers.google.com/protocol-buffers/docs/encoding?csw=1#varints">Base                         * 128 Varints</a> integer length field. For example:                         * <pre>                         * BEFORE ENCODE (300 bytes)       AFTER ENCODE (302 bytes)                         * +---------------+               +--------+---------------+                         * | Protobuf Data |-------------->| Length | Protobuf Data |                         * |  (300 bytes)  |               | 0xAC02 |  (300 bytes)  |                         * +---------------+               +--------+---------------+                         * </pre> *                         */                        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);    }}

SubReqServerHandler.java

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();    }}

客户端

SubReqClient.java

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<SocketChannel>() {                    @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解码器，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                         * <a href="https://developers.google.com/protocol-buffers/docs/encoding?csw=1#varints">Base                         * 128 Varints</a> integer length field. For example:                         * <pre>                         * BEFORE ENCODE (300 bytes)       AFTER ENCODE (302 bytes)                         * +---------------+               +--------+---------------+                         * | Protobuf Data |-------------->| Length | Protobuf Data |                         * |  (300 bytes)  |               | 0xAC02 |  (300 bytes)  |                         * +---------------+               +--------+---------------+                         * </pre> *                         */                        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);    }}

SubReqClientHandler.java

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<String> 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();    }}

测试

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"]