netty学习笔记7-netty使用Google的ProtoBuff完成RPC服务的通信
需求：
使用netty完成一个RPC服务器的编写和调用，在通信的过程中使用protobuff来传递数据
前提：
protobuff官网：https://developers.google.com/protocol-buffers/ (需要)
困惑：
RPC和RMI的区别？
原理都是类似的，只是RMI是使用Java编写的不能跨语言，RPC是支持跨语言的
RPC和webservice的区别
webservice 使用http协议进行通信，RPC使用socket进行通信，socket效率更高
webservice使用xml进行数据通信,xml最臭名昭著的就是比较占空间，而且遍历和查找很不方法,rpc使用体积更小，速度更快，解析更强的框架进行数据传递(数据的压缩比决定了数据的大小),日入使用Google protobuff 、grpc、apache thrift等。
protobuf 的学习过程
1. 首先找到官网学习一下什么是protobuf
2. 下载protobuf的编译器(https://github.com/google/protobuf)
3. 配置protobuff编译器的环境变量
4. 阅读protobuff的文档(https://developers.google.com/protocol-buffers/docs/javatutorial)
编写protobuff程序主要有散步
5. protobuff解决的问题
netty集成protobufff完成RPC的方法调用
实现步骤:
1. 进入protobuff需要jar包
2. 编写protobuff的.proto文件(该文件我们也成为idl（interface description language）文件)
syntax = "proto2";
package com.baidu.netty.proto;
option java_package = "com.baidu.netty.sixExample";
option java_outer_classname = "TeacherData";
option optimize_for=SPEED;
message Teacher
{
required int32 id = 1;
optional string name = 2;
enum GenderType
{
MALE = 0;
FEMALE = 1;
}
message Student
{
required int32 id = 1;
optional string name = 2;
optional string email = 3;
optional GenderType gender = 4 [default = MALE];
}
}
3. 使用protobuff的编译器生产代码(几乎所有的RPC框架都有代码生成框架)
protoc --java_out=代码存放的目录 .proto文件存放的位置
4. 简单测试生成的类是否能够使用
package com.baidu.netty.sixExample;
public class TestTearcher {
public static void main(String[] args) throws Exception{
TeacherData.Teacher teacher = TeacherData.Teacher.newBuilder().setId(1).setName("老徐").build();
System.out.println(teacher.getName());
//对象的序列号
byte[] temp = teacher.toByteArray();
//对象的反序列号
TeacherData.Teacher teacher1 = TeacherData.Teacher.parseFrom(temp);
System.out.println(teacher1.getName());
}
}
5. 编写netty的服务器端启动程序
package com.baidu.netty.sixExample;
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;
public class MyServer {
public static void main(String[] args) throws Exception{
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class).childHandler(new MyServerInitializer());
ChannelFuture future = bootstrap.bind(8899).sync();
future.channel().closeFuture().sync();
}finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
6. 编写服务器端初始化类
package com.baidu.netty.sixExample;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
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;
public class MyServerInitializer extends ChannelInitializer {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new ProtobufVarint32FrameDecoder());
pipeline.addLast(new ProtobufDecoder(TeacherData.Teacher.getDefaultInstance()));
pipeline.addLast(new ProtobufVarint32LengthFieldPrepender());
pipeline.addLast(new ProtobufEncoder());
pipeline.addLast(new MyServerHandler());
}
}
7. 编写服务器端处理类
package com.baidu.netty.sixExample;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
public class MyServerHandler extends SimpleChannelInboundHandler {
@Override
protected void channelRead0(ChannelHandlerContext ctx, TeacherData.Teacher msg) throws Exception {
System.out.println(msg.getName());
System.out.println(msg.getId());
}
}
8. 编写客户端启动类
package com.baidu.netty.sixExample;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
public class MyClient {
public static void main(String[] args) throws Exception{
EventLoopGroup client = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(client).channel(NioSocketChannel.class).handler(new MyClientInitializer());
ChannelFuture future = bootstrap.connect("localhost",8899).sync();
Channel channel = future.channel();
TeacherData.Teacher teacher = TeacherData.Teacher.newBuilder().setName("老徐").setId(1).build();
channel.writeAndFlush(teacher);
channel.closeFuture().sync();
}finally {
client.shutdownGracefully();
}
}
}
9. 编写客户端初始化类
package com.baidu.netty.sixExample;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
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;
public class MyClientInitializer extends ChannelInitializer {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new ProtobufVarint32FrameDecoder());
pipeline.addLast(new ProtobufDecoder(TeacherData.Teacher.getDefaultInstance()));
pipeline.addLast(new ProtobufVarint32LengthFieldPrepender());
pipeline.addLast(new ProtobufEncoder());
}
}