出处：
我们来使用Protobuf进行序列化，它和XML，json一样都有自己的语法，xml的后缀是.xml，json文件的后缀是.json，自然Protobuf文件的后缀就是.proto（哈哈，当然不是全称）。
下面我们使用Protobuf来封装一段消息，通过一个案例简单介绍一下它的使用。
option java_package = "cn.edu.hust.netty.demo10";
option java_outer_classname = "MessageProto";
message RequestMsg{
required bytes msgType = 1;
required string receiveOne = 2;
required string msg = 3;
}
message ResponseMsg{
required bytes msgType = 1;
required string receiveOne = 2;
required string msg = 3;
}
字段修饰符：
字符类型稍微有些不同：double,float,int32,int64,bool(boolean),string,bytes。稍微有些不同，String，boolean，int有差别。
另外我们看到上面3个字段分别赋值了，这个值是什么意思呢？消息定义中，每个字段都有唯一的一个数字标识符。这些标识符是用来在消息的二进制格式中识别各个字段的，一旦开始使用就不能够再改变。注：[1,15]之内的标识号在编码的时候会占用一个字节。[16,2047]之内的标识号则占用2个字节。所以应该为那些频繁出现的消息元素保留 [1,15]之内的标识号。
关于Protobuf 的语法我们就简单的介绍这么多，更多细节大家自己去查阅文档吧。下面我们开始使用Protobuf 来进行序列化。这个分享给你。
首先我们的在工程中引入protobuf的jar包，目前官方版本最高3.2，我们用3.0的吧：
com.google.protobuf
protobuf-java
3.0.2
Protobuf的文件已经定义好了，下就需要把它编译成java代码，这里我们的借助到google为我们提供的脚本工具protoc，链接在这里，点击下载这里提供的是protoc-3.0.2。
要注意protoc的版本需要和Protobuf的版本对应上，不然不同的版本之间会有一些差异解析可能会有问题。现在知道我们为啥非得选用protobuf3.0.2版本吧，因为我没有找到别的版本的protoc。。。
下载好了我们解压缩然后把刚才写好的Msg.proto文件复制进去。
接着我们进cmd输入如下命令：
主要是第三句命令。如果你输入没有报错的话你的proto文件夹应该会生成一个子文件夹：
进去该文件夹你会看到已经生成了MessageProto.java文件，恭喜你，这时候你已经完成了protobuf序列化文件的生成。然后你把该文件拷贝至工程目录下。
接下来我们用生成的文件去发消息吧。还是老套路服务端和客户端。另外，微信搜索Java技术栈，在后台回复：面试，可以获取我整理的 Java 系列面试题和答案，非常齐全。
{ @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32FrameDecoder()); pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance())); pipeline.addLast(new ProtoBufServerHandler()); }}服务端handler：public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder(); builder.setMsgType(ByteString.copyFromUtf8("CBSP")); builder.setReceiveOne("小红"); builder.setMsg("你好，你有啥事"); ctx.writeAndFlush(builder.build()); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg; System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg()); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { super.exceptionCaught(ctx, cause); ctx.close(); }}客户端：public class ProtoBufClient { private int port; private String address; public ProtoBufClient(int port, String address) { this.port = port; this.address = address; } public void start(){ EventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ClientChannelInitializer()); try { ChannelFuture future = bootstrap.connect(address,port).sync(); future.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally { group.shutdownGracefully(); } } public static void main(String[] args) { ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1"); client.start(); }}客户端Initializer：public class ClientChannelInitializer extends ChannelInitializer { protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32LengthFieldPrepender()); pipeline.addLast(new ProtobufEncoder()); pipeline.addLast(new ProtoBufClientHandler()); }}客户端handler：" data-itemshowtype="0" tab="innerlink" data-linktype="2">public class ProtoBufServer {
private int port;
public ProtoBufServer(int port) {
this.port = port;
}
public void start(){
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEventLoopGroup();
ServerBootstrap server = new ServerBootstrap().group(bossGroup,workGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ServerChannelInitializer());
try {
ChannelFuture future = server.bind(port).sync();
future.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
}finally {
bossGroup.shutdownGracefully();
workGroup.shutdownGracefully();
}
}
public static void main(String[] args) {
ProtoBufServer server = new ProtoBufServer(7788);
server.start();
}
}
{ @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32FrameDecoder()); pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance())); pipeline.addLast(new ProtoBufServerHandler()); }}服务端handler：public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder(); builder.setMsgType(ByteString.copyFromUtf8("CBSP")); builder.setReceiveOne("小红"); builder.setMsg("你好，你有啥事"); ctx.writeAndFlush(builder.build()); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg; System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg()); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { super.exceptionCaught(ctx, cause); ctx.close(); }}客户端：public class ProtoBufClient { private int port; private String address; public ProtoBufClient(int port, String address) { this.port = port; this.address = address; } public void start(){ EventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ClientChannelInitializer()); try { ChannelFuture future = bootstrap.connect(address,port).sync(); future.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally { group.shutdownGracefully(); } } public static void main(String[] args) { ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1"); client.start(); }}客户端Initializer：public class ClientChannelInitializer extends ChannelInitializer { protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32LengthFieldPrepender()); pipeline.addLast(new ProtobufEncoder()); pipeline.addLast(new ProtoBufClientHandler()); }}客户端handler：" data-itemshowtype="0" tab="innerlink" data-linktype="2">public class ServerChannelInitializer extends ChannelInitializer {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(new ProtobufVarint32FrameDecoder());
pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance()));
pipeline.addLast(new ProtoBufServerHandler());
}
}
{ @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32FrameDecoder()); pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance())); pipeline.addLast(new ProtoBufServerHandler()); }}服务端handler：public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder(); builder.setMsgType(ByteString.copyFromUtf8("CBSP")); builder.setReceiveOne("小红"); builder.setMsg("你好，你有啥事"); ctx.writeAndFlush(builder.build()); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg; System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg()); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { super.exceptionCaught(ctx, cause); ctx.close(); }}客户端：public class ProtoBufClient { private int port; private String address; public ProtoBufClient(int port, String address) { this.port = port; this.address = address; } public void start(){ EventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ClientChannelInitializer()); try { ChannelFuture future = bootstrap.connect(address,port).sync(); future.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally { group.shutdownGracefully(); } } public static void main(String[] args) { ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1"); client.start(); }}客户端Initializer：public class ClientChannelInitializer extends ChannelInitializer { protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32LengthFieldPrepender()); pipeline.addLast(new ProtobufEncoder()); pipeline.addLast(new ProtoBufClientHandler()); }}客户端handler：" data-itemshowtype="0" tab="innerlink" data-linktype="2">public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder();
builder.setMsgType(ByteString.copyFromUtf8("CBSP"));
builder.setReceiveOne("小红");
builder.setMsg("你好，你有啥事");
ctx.writeAndFlush(builder.build());
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg;
System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
super.exceptionCaught(ctx, cause);
ctx.close();
}
}
{ @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32FrameDecoder()); pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance())); pipeline.addLast(new ProtoBufServerHandler()); }}服务端handler：public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder(); builder.setMsgType(ByteString.copyFromUtf8("CBSP")); builder.setReceiveOne("小红"); builder.setMsg("你好，你有啥事"); ctx.writeAndFlush(builder.build()); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg; System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg()); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { super.exceptionCaught(ctx, cause); ctx.close(); }}客户端：public class ProtoBufClient { private int port; private String address; public ProtoBufClient(int port, String address) { this.port = port; this.address = address; } public void start(){ EventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ClientChannelInitializer()); try { ChannelFuture future = bootstrap.connect(address,port).sync(); future.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally { group.shutdownGracefully(); } } public static void main(String[] args) { ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1"); client.start(); }}客户端Initializer：public class ClientChannelInitializer extends ChannelInitializer { protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32LengthFieldPrepender()); pipeline.addLast(new ProtobufEncoder()); pipeline.addLast(new ProtoBufClientHandler()); }}客户端handler：" data-itemshowtype="0" tab="innerlink" data-linktype="2">public class ProtoBufClient {
private int port;
private String address;
public ProtoBufClient(int port, String address) {
this.port = port;
this.address = address;
}
public void start(){
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group)
.channel(NioSocketChannel.class)
.handler(new ClientChannelInitializer());
try {
ChannelFuture future = bootstrap.connect(address,port).sync();
future.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
}finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) {
ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1");
client.start();
}
}
{ @Override protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32FrameDecoder()); pipeline.addLast(new ProtobufDecoder(MessageProto.RequestMsg.getDefaultInstance())); pipeline.addLast(new ProtoBufServerHandler()); }}服务端handler：public class ProtoBufServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { MessageProto.ResponseMsg.Builder builder = MessageProto.ResponseMsg.newBuilder(); builder.setMsgType(ByteString.copyFromUtf8("CBSP")); builder.setReceiveOne("小红"); builder.setMsg("你好，你有啥事"); ctx.writeAndFlush(builder.build()); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { MessageProto.RequestMsg m = (MessageProto.RequestMsg)msg; System.out.println("Client say: "+m.getReceiveOne()+","+m.getMsg()); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { super.exceptionCaught(ctx, cause); ctx.close(); }}客户端：public class ProtoBufClient { private int port; private String address; public ProtoBufClient(int port, String address) { this.port = port; this.address = address; } public void start(){ EventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group) .channel(NioSocketChannel.class) .handler(new ClientChannelInitializer()); try { ChannelFuture future = bootstrap.connect(address,port).sync(); future.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally { group.shutdownGracefully(); } } public static void main(String[] args) { ProtoBufClient client = new ProtoBufClient(7788,"127.0.0.1"); client.start(); }}客户端Initializer：public class ClientChannelInitializer extends ChannelInitializer { protected void initChannel(SocketChannel socketChannel) throws Exception { ChannelPipeline pipeline = socketChannel.pipeline(); pipeline.addLast(new ProtobufVarint32LengthFieldPrepender()); pipeline.addLast(new ProtobufEncoder()); pipeline.addLast(new ProtoBufClientHandler()); }}客户端handler：" data-itemshowtype="0" tab="innerlink" data-linktype="2">public class ClientChannelInitializer extends ChannelInitializer {
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(new ProtobufVarint32LengthFieldPrepender());
pipeline.addLast(new ProtobufEncoder());
pipeline.addLast(new ProtoBufClientHandler());
}
}
public class ProtoBufClientHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
MessageProto.ResponseMsg m = (MessageProto.ResponseMsg)msg;
System.out.println("Server say: "+m.getReceiveOne()+","+m.getMsg());
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
MessageProto.RequestMsg.Builder builder = MessageProto.RequestMsg.newBuilder();
builder.setMsgType(ByteString.copyFromUtf8("CBSP"));
builder.setReceiveOne("小明");
builder.setMsg("你好，我找你有事");
ctx.writeAndFlush(builder.build());
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("Client is close");
}
}
启动服务端和客户端，输出如下：
最简单的protoBuf应用案例我们就写完了，真实的使用场景大同小异，随机应变即可。另外，关注公众号Java技术栈，在后台回复：面试，可以获取我整理的 Java 系列面试题和答案，非常齐全。
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