前言
Dubbo是基于Netty搭建的RPC框架，为了更好地理解Netty在Dubbo中的应用，仿照Dubbo搭建了一个简易版的RPC框架。
概述
整个调用逻辑如下：
1、生产者服务端启动Netty服务端。
2、消费者客户端通过JDK动态代理启动Netty客户端，通过注册中心地址连接生产者服务端，同时将接口调用信息（接口、方法、参数等）先序列化再发送给生产者服务端。
3、生产者服务端接收消息并通过反射调用相应方法，然后返回调用结果给消费者。
4、消费者接收生产者传来的调用结果。
实现
新建DubboRequest类(相当于POJO)，作为消息载体
package com.beidao.netty.dubbo.facade.api;
import java.io.Serializable;
import java.util.Arrays;
/**
* dubbo请求类
* @author 0200759
*
*/
public class DubboRequest implements Serializable{
private static final long serialVersionUID = 422805234202183587L;
private Class<?> interfaceClass;
private String methodName;
private Class<?>[] paramTypes;
private Object[] args;
public DubboRequest(Class<?> interfaceClass, String methodName, Class<?>[] paramTypes, Object[] args) {
this.interfaceClass = interfaceClass;
this.methodName = methodName;
this.paramTypes = paramTypes;
this.args = args;
}
public Class<?> getInterfaceClass() {
return interfaceClass;
}
public void setInterfaceClass(Class<?> interfaceClass) {
this.interfaceClass = interfaceClass;
}
public String getMethodName() {
return methodName;
}
public void setMethodName(String methodName) {
this.methodName = methodName;
}
public Class<?>[] getParamTypes() {
return paramTypes;
}
public void setParamTypes(Class<?>[] paramTypes) {
this.paramTypes = paramTypes;
}
public Object[] getArgs() {
return args;
}
public void setArgs(Object[] args) {
this.args = args;
}
@Override
public String toString() {
return "DubboRequest{" +
"interfaceClass=" + interfaceClass +
", methodName='" + methodName + '\'' +
", paramTypes=" + Arrays.toString(paramTypes) +
", args=" + Arrays.toString(args) +
'}';
}
}
新建Dubbo消费者调用接口IUserFacade
package com.beidao.netty.dubbo.facade.api;
/**
* dubbo api接口
* @author 0200759
*
*/
public interface IUserFacade {
/**
* 返回用户名接口
* @param string
* @return
*/
public String getUserName(Long id);
}
新建Dubbo消费者拦截器
package com.beidao.netty.dubbo.client;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import com.beidao.netty.dubbo.facade.api.DubboRequest;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
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.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
/**
* dubbo消费者拦截器
* @author 0200759
*
*/
public class DubboConsumerHandler implements InvocationHandler{
private Object res;
public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group).channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true).handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new ObjectDecoder(1024, ClassResolvers.cacheDisabled(this.getClass().getClassLoader())));
ch.pipeline().addLast(new ObjectEncoder());
ch.pipeline().addLast(new ConsumerHandler(proxy, method, args));
}
});
//从注册中心获取服务端ip和端口
ChannelFuture f = bootstrap.connect("127.0.0.1", 8080).sync();
f.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
return res;
}
/**
*
* netty-dubbo消费者拦截器
* @author 0200759
*
*/
private class ConsumerHandler extends ChannelInboundHandlerAdapter{
private Object proxy;
private Method method;
private Object[] args;
public ConsumerHandler(Object proxy, Method method, Object[] args) {
this.proxy = proxy;
this.args = args;
this.method = method;
}
public void channelActive(ChannelHandlerContext ctx) {
// 传输的对象必须实现序列化接口 包括其中的属性
DubboRequest req = new DubboRequest(proxy.getClass().getInterfaces()[0], method.getName(), method.getParameterTypes(), args);
ctx.write(req);
ctx.flush();
}
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("调用成功");
res = msg;
ctx.flush();
//收到响应后断开连接
ctx.close();
}
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
}
}
新建Dubbo服务代理类
package com.beidao.netty.dubbo.client;
import java.lang.reflect.Proxy;
/**
* Dubbo代理类
* @author 0200759
*
*/
public class DubboProxy {
public static Object getProxyInstance(Class<?> clazz) {
return Proxy.newProxyInstance(clazz.getClassLoader(), new Class[]{clazz}, new DubboConsumerHandler());
}
}
新建Dubbo消费者
package com.beidao.netty.dubbo.client;
import com.beidao.netty.dubbo.facade.api.IUserFacade;
/**
* dubbo客户端(消费者)
* @author 0200759
*
*/
public class DubboClient {
public static void main(String[] args){
IUserFacade userFacade = (IUserFacade) DubboProxy.getProxyInstance(IUserFacade.class);
System.out.println(userFacade.getUserName(520L));
System.out.println(userFacade.getUserName(1314L));
System.out.println(userFacade.getUserName(1314520L));
}
}
新建 dubbo服务端实现类
package com.beidao.netty.dubbo.facade.impl;
import com.beidao.netty.dubbo.facade.api.IUserFacade;
/**
* dubbo服务端实现类
* @author 0200759
*
*/
public class UserFacade implements IUserFacade {
public String getUserName(Long id) {
return "I love you, "+id;
}
}
dubbo生产者拦截器
package com.beidao.netty.dubbo.sever;
import java.lang.reflect.Method;
import com.beidao.netty.dubbo.facade.api.DubboRequest;
import com.beidao.netty.dubbo.facade.api.IUserFacade;
import com.beidao.netty.dubbo.facade.impl.UserFacade;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
/**
* netty-dubbo服务端拦截器
* @author 0200759
*
*/
public class DubboServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("服务端收到消息: " + msg);
DubboRequest req = (DubboRequest) msg;
// 1. 根据类名返回对象
Object target = this.getInstenceByInterfaceClass(req.getInterfaceClass());
// 2. 获取方法名
String methodName = req.getMethodName();
// 3. 获取方法参数类型
// 4. 获取方法
Method method = target.getClass().getMethod(methodName, req.getParamTypes());
// 5. 获取参数值
//调用方法 获取返回值
Object res = method.invoke(target, req.getArgs());
// 写回给调用端
ctx.writeAndFlush(res);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
/**
* 根据接口返回对应的实例
* @param clazz
* @return
*/
private Object getInstenceByInterfaceClass(Class<?> clazz) {
if (IUserFacade.class.equals(clazz)) {
return new UserFacade();
}
return null;
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
super.exceptionCaught(ctx, cause);
}
}
Dubbo生产者服务端
package com.beidao.netty.dubbo.sever;
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.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
/**
* @author 0200759
*
*/
public class DubboServer {
private int port;
public DubboServer(int port) {
this.port = port;
}
public void run() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new ObjectDecoder(1024*1024, ClassResolvers.weakCachingConcurrentResolver(this.getClass().getClassLoader())));
ch.pipeline().addLast(new ObjectEncoder());
ch.pipeline().addLast(new DubboServerHandler());
}
})
.option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);
// Bind and start to accept incoming connections.
ChannelFuture f = b.bind(port).sync(); // (7)
f.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new DubboServer(8080).run();
}
}
验证
1、启动生产者服务端DubboServer。
2、启动消费者调用端DubboClient。
消费者客户端控制台显示如下：
调用成功
I love you, 520
调用成功
I love you, 1314
调用成功
I love you, 1314520
生产者服务端控制台显示如下：
服务端收到消息: DubboRequest{interfaceClass=interface com.beidao.netty.dubbo.facade.api.IUserFacade, methodName='getUserName', paramTypes=[class java.lang.Long], args=[520]}
服务端收到消息: DubboRequest{interfaceClass=interface com.beidao.netty.dubbo.facade.api.IUserFacade, methodName='getUserName', paramTypes=[class java.lang.Long], args=[1314]}
服务端收到消息: DubboRequest{interfaceClass=interface com.beidao.netty.dubbo.facade.api.IUserFacade, methodName='getUserName', paramTypes=[class java.lang.Long], args=[1314520]}
源码地址：https://github.com/MAXAmbitious/netty-study/tree/master/netty-dubbo
