前言：
当前同学们对“java客户端和服务端”大概比较注意，我们都想要分析一些“java客户端和服务端”的相关资讯。那么小编同时在网摘上汇集了一些对于“java客户端和服务端””的相关知识，希望朋友们能喜欢，大家快快来了解一下吧！说明
java 从零开始手写 RPC (01) 基于 websocket 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。
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;/** * <p> 计算服务接口 </p> * * <pre> Created: 2018/8/24 下午4:47 </pre> * <pre> Project: fake </pre> * * @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;/** * <p> 请求入参 </p> * * <pre> Created: 2018/8/24 下午5:05 </pre> * <pre> Project: fake </pre> * * @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;/** * <p> 请求入参 </p> * * <pre> Created: 2018/8/24 下午5:05 </pre> * <pre> Project: fake </pre> * * @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<Channel>(){ @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;/** * <p> 客户端处理类 </p> * * <pre> Created: 2019/10/16 11:30 下午 </pre> * <pre> Project: rpc </pre> * * @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<CalculateRequest> { @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<Object> out) throws Exception { boolean success = in.readBoolean(); int sum = in.readInt(); CalculateResponse response = new CalculateResponse(success, sum); out.add(response); }}服务端设置处理类RpcServer 中的处理类要稍微调整一下，其他的保持不变。
ServerBootstrap serverBootstrap = new ServerBootstrap();serverBootstrap.group(workerGroup, bossGroup) .channel(NioServerSocketChannel.class) // 打印日志 .handler(new LoggingHandler(LogLevel.INFO)) .childHandler(new ChannelInitializer<Channel>() { @Override protected void initChannel(Channel ch) throws Exception { ch.pipeline() .addLast(new CalculateRequestDecoder()) .addLast(new CalculateResponseEncoder()) .addLast(new RpcServerHandler()); } }) // 这个参数影响的是还没有被accept 取出的连接 .option(ChannelOption.SO_BACKLOG, 128) // 这个参数只是过一段时间内客户端没有响应，服务端会发送一个 ack 包，以判断客户端是否还活着。 .childOption(ChannelOption.SO_KEEPALIVE, true);RpcServerHandler一开始这里是空实现，我们来添加一下对应的实现。
package com.github.houbb.rpc.server.handler;import com.github.houbb.log.integration.core.Log;import com.github.houbb.log.integration.core.LogFactory;import com.github.houbb.rpc.common.model.CalculateRequest;import com.github.houbb.rpc.common.model.CalculateResponse;import com.github.houbb.rpc.common.service.Calculator;import com.github.houbb.rpc.server.service.CalculatorService;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.SimpleChannelInboundHandler;/** * @author binbin.hou * @since 0.0.1 */public class RpcServerHandler extends SimpleChannelInboundHandler { private static final Log log = LogFactory.getLog(RpcServerHandler.class); @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { final String id = ctx.channel().id().asLongText(); log.info("[Server] channel {} connected " + id); } @Override protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception { final String id = ctx.channel().id().asLongText(); CalculateRequest request = (CalculateRequest)msg; log.info("[Server] receive channel {} request: {} from ", id, request); Calculator calculator = new CalculatorService(); CalculateResponse response = calculator.sum(request); // 回写到 client 端 ctx.writeAndFlush(response); log.info("[Server] channel {} response {}", id, response); }}读取到客户端的访问之后，我们获取到计算的入参 CalculateRequest，然后调用 sum 方法，获取到对应的 CalculateResponse，将结果通知客户端。
CalculateRequestDecoder
这里和客户端是一一对应的，我们首先把 netty 传递的基本类型转换为 CalculateRequest 对象。
package com.github.houbb.rpc.server.decoder;import com.github.houbb.rpc.common.model.CalculateRequest;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandlerContext;import io.netty.handler.codec.ByteToMessageDecoder;import java.util.List;/** * 请求参数解码 * @author binbin.hou * @since 0.0.3 */public class CalculateRequestDecoder extends ByteToMessageDecoder { @Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception { int one = in.readInt(); int two = in.readInt(); CalculateRequest request = new CalculateRequest(one, two); out.add(request); }}CalculateResponseEncoder这里和客户端类似，我们需要把 response 转换为基本类型进行网络传输。
package com.github.houbb.rpc.server.encoder;import com.github.houbb.rpc.common.model.CalculateResponse;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 CalculateResponseEncoder extends MessageToByteEncoder<CalculateResponse> { @Override protected void encode(ChannelHandlerContext ctx, CalculateResponse msg, ByteBuf out) throws Exception { boolean success = msg.isSuccess(); int result = msg.getSum(); out.writeBoolean(success); out.writeInt(result); }}CalculatorService服务端对应的实现类。
public class CalculatorService implements Calculator { @Override public CalculateResponse sum(CalculateRequest request) { int sum = request.getOne()+request.getTwo(); return new CalculateResponse(true, sum); }}测试服务端启动服务端：
new RpcServer().start();
服务端启动日志：
[DEBUG] [2021-10-05 11:53:11.795] [main] [c.g.h.l.i.c.LogFactory.setImplementation] - Logging initialized using 'class com.github.houbb.log.integration.adaptors.stdout.StdOutExImpl' adapter.[INFO] [2021-10-05 11:53:11.807] [Thread-0] [c.g.h.r.s.c.RpcServer.run] - RPC 服务开始启动服务端十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler channelRegistered信息: [id: 0xd399474f] REGISTERED十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler bind信息: [id: 0xd399474f] BIND: 0.0.0.0/0.0.0.0:9527十月 05, 2021 11:53:13 上午 io.netty.handler.logging.LoggingHandler channelActive信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] ACTIVE[INFO] [2021-10-05 11:53:13.101] [Thread-0] [c.g.h.r.s.c.RpcServer.run] - RPC 服务端启动完成，监听【9527】端口客户端
启动客户端：
new RpcClient().start();
日志如下：
[DEBUG] [2021-10-05 11:54:12.158] [main] [c.g.h.l.i.c.LogFactory.setImplementation] - Logging initialized using 'class com.github.houbb.log.integration.adaptors.stdout.StdOutExImpl' adapter.[INFO] [2021-10-05 11:54:12.164] [Thread-0] [c.g.h.r.c.c.RpcClient.run] - RPC 服务开始启动客户端十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRegistered信息: [id: 0x4d75c580] REGISTERED十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler connect信息: [id: 0x4d75c580] CONNECT: /127.0.0.1:9527十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelActive信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] ACTIVE[INFO] [2021-10-05 11:54:13.403] [Thread-0] [c.g.h.r.c.c.RpcClient.run] - RPC 服务启动客户端完成，监听端口：9527十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler write信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] WRITE: 8B +-------------------------------------------------+ | 0 1 2 3 4 5 6 7 8 9 a b c d e f |+--------+-------------------------------------------------+----------------+|00000000| 00 00 00 01 00 00 00 02 |........ |+--------+-------------------------------------------------+----------------+十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler flush信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] FLUSH[INFO] [2021-10-05 11:54:13.450] [nioEventLoopGroup-2-1] [c.g.h.r.c.c.RpcClient.channelActive] - [Client] request is :CalculateRequest{one=1, two=2}十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRead信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] READ: 5B +-------------------------------------------------+ | 0 1 2 3 4 5 6 7 8 9 a b c d e f |+--------+-------------------------------------------------+----------------+|00000000| 01 00 00 00 03 |..... |+--------+-------------------------------------------------+----------------+十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelReadComplete信息: [id: 0x4d75c580, L:/127.0.0.1:54030 - R:/127.0.0.1:9527] READ COMPLETE[INFO] [2021-10-05 11:54:13.508] [nioEventLoopGroup-2-1] [c.g.h.r.c.c.RpcClient.channelRead0] - [Client] response is :CalculateResponse{success=true, sum=3}可以看到，输出了对应的请求参数和响应结果。
当然，此时服务端也有对应的新增日志：
十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelRead信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] READ: [id: 0xbc9f5927, L:/127.0.0.1:9527 - R:/127.0.0.1:54030]十月 05, 2021 11:54:13 上午 io.netty.handler.logging.LoggingHandler channelReadComplete信息: [id: 0xd399474f, L:/0:0:0:0:0:0:0:0:9527] READ COMPLETE[INFO] [2021-10-05 11:54:13.432] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelActive] - [Server] channel {} connected 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927[INFO] [2021-10-05 11:54:13.495] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] receive channel 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927 request: CalculateRequest{one=1, two=2} from [INFO] [2021-10-05 11:54:13.505] [nioEventLoopGroup-2-1] [c.g.h.r.s.h.RpcServerHandler.channelRead0] - [Server] channel 00e04cfffe360988-00001d34-00000001-2a80d950d8166c0c-bc9f5927 response CalculateResponse{success=true, sum=3}小结为了便于大家学习，以上源码已经开源：
希望本文对你有所帮助，如果喜欢，欢迎点赞收藏转发一波。
我是老马，期待与你的下次相遇。
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标签： #java客户端和服务端 #java客户端和服务端发送
