Java 从零开始手写 RPC—如何实现客户端调用服务端？

发布时间：2021-11-04 10:05 所属栏目：51 来源：互联网

导读：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.comm

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;

/**

* 计算服务接口

* <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;

/**

* 请求入参

* <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;

/**

* 请求入参

* <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;

/**

* 客户端处理类

* <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.chan

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