说明 java 从零开始手写 RPC (01) 基于 socket 实现
java 从零开始手写 RPC (02)-netty4 实现客户端和服务端
写完了客户端和服务端，那么如何实现客户端和服务端的调用呢？
下面就让我们一起来看一下。

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接口定义 计算方法

package com.github.houbb.rpc.common.service; import com.github.houbb.rpc.common.model.CalculateRequest; import com.github.houbb.rpc.common.model.CalculateResponse; /** * 计算服务接口
* *

Created: 2018/8/24 下午4:47

*

Project: fake

* * @author houbinbin * @since 0.0.1 */ public interface Calculator {/** * 计算加法 * @param request 请求入参 * @return 返回结果 */ CalculateResponse sum(final CalculateRequest request); }

pojo 对应的参数对象：

• CalculateRequest

package com.github.houbb.rpc.common.model; import java.io.Serializable; /** * 请求入参
* *

Created: 2018/8/24 下午5:05

*

Project: fake

* * @author houbinbin * @since 0.0.3 */ public class CalculateRequest implements Serializable {private static final long serialVersionUID = 6420751004355300996L; /** * 参数一 */ private int one; /** * 参数二 */ private int two; public CalculateRequest() { }public CalculateRequest(int one, int two) { this.one = one; this.two = two; }//getter setter toString}

• CalculateResponse

package com.github.houbb.rpc.common.model; import java.io.Serializable; /** * 请求入参
* *

Created: 2018/8/24 下午5:05

*

Project: fake

* * @author houbinbin * @since 0.0.3 */ public class CalculateResponse implements Serializable {private static final long serialVersionUID = -1972014736222511341L; /** * 是否成功 */ private boolean success; /** * 二者的和 */ private int sum; public CalculateResponse() { }public CalculateResponse(boolean success, int sum) { this.success = success; this.sum = sum; }//getter setter toString }

客户端 核心部分 RpcClient 需要添加对应的 Handler，调整如下：

Bootstrap bootstrap = new Bootstrap(); ChannelFuture channelFuture = bootstrap.group(workerGroup) .channel(NioSocketChannel.class) .option(ChannelOption.SO_KEEPALIVE, true) .handler(new ChannelInitializer(){ @Override protected void initChannel(Channel ch) throws Exception { ch.pipeline() .addLast(new LoggingHandler(LogLevel.INFO)) .addLast(new CalculateRequestEncoder()) .addLast(new CalculateResponseDecoder()) .addLast(new RpcClientHandler()); } }) .connect(RpcConstant.ADDRESS, port) .syncUninterruptibly();

netty 中的 handler 泳道设计的非常优雅，让我们的代码可以非常灵活地进行拓展。
接下来我们看一下对应的实现。
RpcClientHandler

package com.github.houbb.rpc.client.handler; import com.github.houbb.log.integration.core.Log; import com.github.houbb.log.integration.core.LogFactory; import com.github.houbb.rpc.client.core.RpcClient; import com.github.houbb.rpc.common.model.CalculateRequest; import com.github.houbb.rpc.common.model.CalculateResponse; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; /** * 客户端处理类
* *

Created: 2019/10/16 11:30 下午

*

Project: rpc

* * @author houbinbin * @since 0.0.2 */ public class RpcClientHandler extends SimpleChannelInboundHandler {private static final Log log = LogFactory.getLog(RpcClient.class); @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { CalculateRequest request = new CalculateRequest(1, 2); ctx.writeAndFlush(request); log.info("[Client] request is :{}", request); }@Override protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception { CalculateResponse response = (CalculateResponse)msg; log.info("[Client] response is :{}", response); }}

这里比较简单，channelActive 中我们直接发起调用，入参的对象为了简单，此处固定写死。
channelRead0 中监听服务端的相应结果，并做日志输出。
CalculateRequestEncoder 请求参数是一个对象，netty 是无法直接传输的，我们将其转换为基本对象：

package com.github.houbb.rpc.client.encoder; import com.github.houbb.rpc.common.model.CalculateRequest; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.MessageToByteEncoder; /** * @author binbin.hou * @since 0.0.3 */ public class CalculateRequestEncoder extends MessageToByteEncoder {@Override protected void encode(ChannelHandlerContext ctx, CalculateRequest msg, ByteBuf out) throws Exception { int one = msg.getOne(); int two = msg.getTwo(); out.writeInt(one); out.writeInt(two); }}

CalculateResponseDecoder 针对服务端的响应，也是同理。
我们需要把基本的类型，封装转换为我们需要的对象。

package com.github.houbb.rpc.client.decoder; import com.github.houbb.rpc.common.model.CalculateResponse; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ByteToMessageDecoder; import java.util.List; /** * 响应参数解码 * @author binbin.hou * @since 0.0.3 */ public class CalculateResponseDecoder extends ByteToMessageDecoder {@Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List