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RPC简介
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RPC，即 Remote Procedure Call（远程过程调用），说得通俗一点就是：调用远程计算机上的服务，就像调用本地服务一样。
RPC 可基于 HTTP 或 TCP 协议，Web Service 就是基于 HTTP 协议的 RPC，它具有良好的跨平台性，但其性能却不如基于 TCP 协议的 RPC。会两方面会直接影响 RPC 的性能，一是传输方式，二是序列化。
众所周知，TCP 是传输层协议，HTTP 是应用层协议，而传输层较应用层更加底层，在数据传输方面，越底层越快，因此，在一般情况下，TCP 一定比 HTTP 快。就序列化而言，Java 提供了默认的序列化方式，但在高并发的情况下，这种方式将会带来一些性能上的瓶颈，于是市面上出现了一系列优秀的序列化框架，比如：Protobuf、Kryo、Hessian、Jackson 等，它们可以取代 Java 默认的序列化，从而提供更高效的性能。
为了支持高并发，传统的阻塞式 IO 显然不太合适，因此我们需要异步的 IO，即 NIO。Java 提供了 NIO 的解决方案，Java 7 也提供了更优秀的 NIO.2 支持，用 Java 实现 NIO 并不是遥不可及的事情，只是需要我们熟悉 NIO 的技术细节。
我们需要将服务部署在分布式环境下的不同节点上，通过服务注册的方式，让客户端来自动发现当前可用的服务，并调用这些服务。这需要一种服务注册表（Service Registry）的组件，让它来注册分布式环境下所有的服务地址（包括：主机名与端口号）。
应用、服务、服务注册表之间的关系见下图：
每台 Server 上可发布多个 Service，这些 Service 共用一个 host 与 port，在分布式环境下会提供 Server 共同对外提供 Service。此外，为防止 Service Registry 出现单点故障，因此需要将其搭建为集群环境。
本文将为您揭晓开发轻量级分布式 RPC 框架的具体过程，该框架基于 TCP 协议，提供了 NIO 特性，提供高效的序列化方式，同时也具备服务注册与发现的能力。
根据以上技术需求，我们可使用如下技术选型：
- Spring：它是最强大的依赖注入框架，也是业界的权威标准。
- Netty：它使 NIO 编程更加容易，屏蔽了 Java 底层的 NIO 细节。
- Protostuff：它基于 Protobuf 序列化框架，面向 POJO，无需编写 .proto 文件。
- ZooKeeper：提供服务注册与发现功能，开发分布式系统的必备选择，同时它也具备天生的集群能力。
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服务端设计配置
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服务接口工程listen-rpc-service
- 主要定义服务接口类和服务涉及到的实体类
- listen-rpc-service工程目录结构图
- listen-rpc-service工程pom.xml
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<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>listen</groupId> <artifactId>listen-parent</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>listen-rpc-service</artifactId> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-common</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.1.41</version> </dependency> </dependencies> </project> - listen-rpc-service工程服务接口IHelloService
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package com.listen.rpc.service; import java.util.List; import com.listen.rpc.entity.User; public interface IHelloService { public String hello(String name); public User getUser(String name); public List<User> getUsers(int size); public User updateUser(User user); } - listen-rpc-service工程User类
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package com.listen.rpc.entity; import java.util.Date; import com.alibaba.fastjson.JSON; public class User { private String name; private Date birthday; private boolean sex; public User(String name, Date birthday, boolean sex){ this.name = name; this.birthday = birthday; this.sex = sex; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public boolean isSex() { return sex; } public void setSex(boolean sex) { this.sex = sex; } public String toString(){ return JSON.toJSONString(this); } } -
工程依赖引用的listen-rpc-common工程
- 主要放置服务端和客户端共用的组件，而且这些组件可以被其他服务包共用，所以要抽取出来
- listen-rpc-common工程目录结构图
- listen-rpc-common工程pom.xml文件
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<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>listen</groupId> <artifactId>listen-parent</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>listen-rpc-common</artifactId> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <!-- Netty --> <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>4.0.24.Final</version> </dependency> <!-- Protostuff --> <dependency> <groupId>com.dyuproject.protostuff</groupId> <artifactId>protostuff-core</artifactId> <version>1.0.8</version> </dependency> <dependency> <groupId>com.dyuproject.protostuff</groupId> <artifactId>protostuff-runtime</artifactId> <version>1.0.8</version> </dependency> <!-- Objenesis --> <dependency> <groupId>org.objenesis</groupId> <artifactId>objenesis</artifactId> <version>2.1</version> </dependency> <!-- Spring --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.2.12.RELEASE</version> </dependency> </dependencies> </project> -
listen-rpc-common工程RpcService注解
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package com.listen.rpc.annotation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import org.springframework.stereotype.Component; @Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Component // 表明可被 Spring 扫描 public @interface RpcService { Class<?> value(); }listen-rpc-common工程Constant接口
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package com.listen.rpc.common; public interface Constant { int ZK_SESSION_TIMEOUT = 5000; //在创建数据节点前，先用zkCli.sh客户端连接上服务端，查看目前存在的数据节点， //把下面的/zookeeper/quota改为你自己的，/zookeeper/quota是我自己Zookeeper的节点 String ZK_REGISTRY_PATH = "/zookeeper/quota"; String ZK_DATA_PATH = ZK_REGISTRY_PATH + "/data"; }listen-rpc-common工程RpcDecoder解码类
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package com.listen.rpc.common; import java.util.List; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ByteToMessageDecoder; public class RpcDecoder extends ByteToMessageDecoder{ private Class<?> genericClass; public RpcDecoder(Class<?> genericClass) { this.genericClass = genericClass; } @Override public final void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception { if (in.readableBytes() < 4) { return; } in.markReaderIndex(); int dataLength = in.readInt(); if (dataLength < 0) { ctx.close(); } if (in.readableBytes() < dataLength) { in.resetReaderIndex(); } byte[] data = new byte[dataLength]; in.readBytes(data); Object obj = SerializationUtil.deserialize(data, genericClass); out.add(obj); } }listen-rpc-common工程RpcEncoder解码类
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package com.listen.rpc.common; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.MessageToByteEncoder; public class RpcEncoder extends MessageToByteEncoder { private Class<?> genericClass; public RpcEncoder(Class<?> genericClass) { this.genericClass = genericClass; } @Override public void encode(ChannelHandlerContext ctx, Object in, ByteBuf out) throws Exception { if (genericClass.isInstance(in)) { byte[] data = SerializationUtil.serialize(in); out.writeInt(data.length); out.writeBytes(data); } } }listen-rpc-common工程RpcRequest请求类
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package com.listen.rpc.common; public class RpcRequest { private String requestId; private String className; private String methodName; private Class<?>[] parameterTypes; private Object[] parameters; public String getRequestId() { return requestId; } public void setRequestId(String requestId) { this.requestId = requestId; } public String getClassName() { return className; } public void setClassName(String className) { this.className = className; } public String getMethodName() { return methodName; } public void setMethodName(String methodName) { this.methodName = methodName; } public Class<?>[] getParameterTypes() { return parameterTypes; } public void setParameterTypes(Class<?>[] parameterTypes) { this.parameterTypes = parameterTypes; } public Object[] getParameters() { return parameters; } public void setParameters(Object[] parameters) { this.parameters = parameters; } }listen-rpc-common工程RpcResponse响应类
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package com.listen.rpc.common; public class RpcResponse { private String requestId; private Throwable error; private Object result; public String getRequestId() { return requestId; } public void setRequestId(String requestId) { this.requestId = requestId; } public Throwable getError() { return error; } public void setError(Throwable error) { this.error = error; } public Object getResult() { return result; } public void setResult(Object result) { this.result = result; } }listen-rpc-common工程SerializationUtil序列化反序列化类
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服务接口实现工程listen-rpc-service-impl
- 主要放置listen-rpc-service接口的实现类，这个工程会依赖公共RPC服务工程listen-rpc-server，listen-rpc-server主要是连接Zookeeper实现服务的注册与发现
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listen-rpc-server工程的目录结构图
- listen-rpc-server工程pom.xml
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<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>listen</groupId> <artifactId>listen-parent</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>listen-rpc-server</artifactId> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-common</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <!-- ZooKeeper --> <dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.6</version> </dependency> <!-- Apache Commons Collections --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-collections4</artifactId> <version>4.0</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-source-plugin</artifactId> <version>2.2.1</version> <executions> <execution> <id>attach-sources</id> <goals> <goal>jar</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <port>8000</port> <path>/</path> </configuration> </plugin> </plugins> </build> </project> -
listen-rpc-server工程RpcServer服务启动类
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package com.listen.rpc.server; import java.util.HashMap; import java.util.Map; import org.apache.commons.collections4.MapUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.BeansException; import org.springframework.beans.factory.InitializingBean; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import com.listen.rpc.annotation.RpcService; import com.listen.rpc.common.RpcDecoder; import com.listen.rpc.common.RpcEncoder; import com.listen.rpc.common.RpcRequest; import com.listen.rpc.common.RpcResponse; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.Channel; 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; public class RpcServer implements ApplicationContextAware, InitializingBean{ private static final Logger LOGGER = LoggerFactory.getLogger(RpcServer.class); private String serverAddress; private ServiceRegistry serviceRegistry; private Map<String, Object> handlerMap = new HashMap<String, Object>(); // 存放接口名与服务对象之间的映射关系 public RpcServer(String serverAddress) { this.serverAddress = serverAddress; } public RpcServer(String serverAddress, ServiceRegistry serviceRegistry) { this.serverAddress = serverAddress; this.serviceRegistry = serviceRegistry; } public void setApplicationContext(ApplicationContext ctx) throws BeansException { Map<String, Object> serviceBeanMap = ctx.getBeansWithAnnotation(RpcService.class); // 获取所有带有 RpcService 注解的 Spring Bean if (MapUtils.isNotEmpty(serviceBeanMap)) { for (Object serviceBean : serviceBeanMap.values()) { String interfaceName = serviceBean.getClass().getAnnotation(RpcService.class).value().getName(); handlerMap.put(interfaceName, serviceBean); } } } public void afterPropertiesSet() throws Exception { EventLoopGroup bossGroup = new NioEventLoopGroup(); EventLoopGroup workerGroup = new NioEventLoopGroup(); try { ServerBootstrap bootstrap = new ServerBootstrap(); bootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) .childHandler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel channel) throws Exception { ((Channel) channel).pipeline() .addLast(new RpcDecoder(RpcRequest.class)) // 将 RPC 请求进行解码（为了处理请求） .addLast(new RpcEncoder(RpcResponse.class)) // 将 RPC 响应进行编码（为了返回响应） .addLast(new RpcHandler(handlerMap)); // 处理 RPC 请求 } }) .option(ChannelOption.SO_BACKLOG, 128) .childOption(ChannelOption.SO_KEEPALIVE, true); String[] array = serverAddress.split(":"); String host = array[0]; int port = Integer.parseInt(array[1]); ChannelFuture future = bootstrap.bind(host, port).sync(); LOGGER.debug("server started on port {}", port); if (serviceRegistry != null) { serviceRegistry.register(serverAddress); // 注册服务地址 } future.channel().closeFuture().sync(); } finally { workerGroup.shutdownGracefully(); bossGroup.shutdownGracefully(); } } }listen-rpc-server工程ServiceRegistry服务注册类
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package com.listen.rpc.server; import java.io.IOException; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooDefs; import org.apache.zookeeper.ZooKeeper; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.listen.rpc.common.Constant; public class ServiceRegistry { private static final Logger LOGGER = LoggerFactory.getLogger(ServiceRegistry.class); private CountDownLatch latch = new CountDownLatch(1); private String registryAddress; public ServiceRegistry(String registryAddress) { this.registryAddress = registryAddress; } public void register(String data) { if (data != null) { ZooKeeper zk = connectServer(); if (zk != null) { createNode(zk, data); } } } private ZooKeeper connectServer() { ZooKeeper zk = null; try { zk = new ZooKeeper(registryAddress, Constant.ZK_SESSION_TIMEOUT, new Watcher() { public void process(WatchedEvent event) { if (event.getState() == Event.KeeperState.SyncConnected) { latch.countDown(); } } }); latch.await(); } catch (IOException e) { LOGGER.error("", e); } catch (InterruptedException e){ LOGGER.error("", e); } return zk; } private void createNode(ZooKeeper zk, String data) { try { byte[] bytes = data.getBytes(); String path = zk.create(Constant.ZK_DATA_PATH, bytes, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); LOGGER.debug("create zookeeper node ({} => {})", path, data); } catch (KeeperException e) { e.printStackTrace(); LOGGER.error("", e); } catch (InterruptedException e){ LOGGER.error("", e); } } }listen-rpc-server工程RpcHandler请求统一处理类
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listen-rpc-service-impl工程目录结构图
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- listen-rpc-service-impl服务实现工程pom.xml
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<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>listen</groupId> <artifactId>listen-parent</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>listen-rpc-service-impl</artifactId> <packaging>war</packaging> <dependencies> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-server</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>3.2.12.RELEASE</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <scope>provided</scope> </dependency> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-service</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-source-plugin</artifactId> <version>2.2.1</version> <executions> <execution> <id>attach-sources</id> <goals> <goal>jar</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <port>8000</port> <path>/</path> </configuration> </plugin> </plugins> </build> </project> -
listen-rpc-service-impl工程HelloServiceImpl服务实现类
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package com.listen.rpc.service.impl; import java.util.ArrayList; import java.util.Calendar; import java.util.Date; import java.util.List; import com.listen.rpc.annotation.RpcService; import com.listen.rpc.entity.User; import com.listen.rpc.service.IHelloService; @RpcService(IHelloService.class)// 指定远程接口 使用 RpcService注解定义在服务接口的实现类上，需要对该实现类指定远程接口，因为实现类可能会实现多个接口，一定要告诉框架哪个才是远程接口。 public class HelloServiceImpl implements IHelloService { public String hello(String name) { String result = "hello" + name; System.out.println(result); return result; } @Override public User getUser(String name) { User user = new User(name, new Date(), true); return user; } @Override public List<User> getUsers(int size) { List<User> list = new ArrayList<User>(); User user = null; String name = "foo"; Date birthday = new Date(); Calendar cal = Calendar.getInstance(); cal.setTime(birthday); for(int i = 0; i < size; i++){ cal.add(Calendar.DAY_OF_MONTH, 1); user = new User(name, cal.getTime(), i%2==0 ? true : false); list.add(user); } return list; } @Override public User updateUser(User user) { user.setName(user.getName() + "-update"); return user; } }listen-rpc-service-impl工程配置文件config.properties
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# ZooKeeper 服务器 registry.address=127.0.0.1:2181 # RPC 服务器 server.address=127.0.0.1:8000 #以上配置表明：连接本地的 ZooKeeper 服务器，并在 8000 端口上发布 RPC 服务。listen-rpc-service-impl工程spring.xml配置文件
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util" xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:cache="http://www.springframework.org/schema/cache" xsi:schemaLocation=" http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-3.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <!-- 自动扫描web包 ,将带有注解的类 纳入spring容器管理 --> <context:component-scan base-package="com.listen.rpc"></context:component-scan> <context:property-placeholder location="classpath:config.properties"/> <!-- 配置服务注册组件 --> <bean id="serviceRegistry" class="com.listen.rpc.server.ServiceRegistry"> <constructor-arg name="registryAddress" value="${registry.address}"/> </bean> <!-- 配置 RPC 服务器 --> <bean id="rpcServer" class="com.listen.rpc.server.RpcServer"> <constructor-arg name="serverAddress" value="${server.address}"/> <constructor-arg name="serviceRegistry" ref="serviceRegistry"/> </bean> </beans>
至此，服务端代码编写完毕，接下来开始编写客户端代码，客户端我打算用springMVC实现服务的测试
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客户端工程listen-rpc-client
- 主要是springMVC实现服务端服务接口的调用测试
- listen-rpc-client工程目录结构图
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- listen-rpc-client工程的pom.xml文件
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<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>listen</groupId> <artifactId>listen-parent</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <artifactId>listen-rpc-client</artifactId> <packaging>war</packaging> <dependencies> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-common</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <dependency> <groupId>listen</groupId> <artifactId>listen-rpc-service</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> <!-- Spring --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.2.12.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>3.2.12.RELEASE</version> </dependency> <!-- ZooKeeper --> <dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.6</version> </dependency> <!-- CGLib --> <dependency> <groupId>cglib</groupId> <artifactId>cglib</artifactId> <version>3.1</version> </dependency> </dependencies> <build> <finalName>listen-rpc-client</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-source-plugin</artifactId> <version>2.2.1</version> <executions> <execution> <id>attach-sources</id> <goals> <goal>jar</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <port>8080</port> <path>/</path> </configuration> </plugin> </plugins> </build> </project> - listen-rpc-client工程HelloController类
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package com.listen.rpc.controller; import java.util.Date; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import com.listen.rpc.client.RpcProxy; import com.listen.rpc.entity.User; import com.listen.rpc.service.IHelloService; @Controller public class HelloController { @Autowired private RpcProxy rpcProxy; @RequestMapping("/hello") public void hello(String name){ IHelloService service = rpcProxy.create(IHelloService.class); String result = service.hello(name); System.out.println(result); } @RequestMapping("/getUser") public void getUser(String name){ IHelloService service = rpcProxy.create(IHelloService.class); System.out.println(service.getUser(name).toString()); } @RequestMapping("/getUsers") public void getUsers(int size){ IHelloService service = rpcProxy.create(IHelloService.class); List<User> list = service.getUsers(size); for(User user : list){ System.out.println(user.toString()); } } @RequestMapping("/updateUser") public void updateUser(String name){ User user = new User(name, new Date(), true); IHelloService service = rpcProxy.create(IHelloService.class); user = service.updateUser(user); System.out.println(user.toString()); } }listen-rpc-client工程代理类RpcProxy
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package com.listen.rpc.client; import java.lang.reflect.Method; import java.util.UUID; import com.listen.rpc.common.RpcRequest; import com.listen.rpc.common.RpcResponse; import net.sf.cglib.proxy.InvocationHandler; import net.sf.cglib.proxy.Proxy; public class RpcProxy { private String serverAddress; private ServiceDiscovery serviceDiscovery; public RpcProxy(String serverAddress) { this.serverAddress = serverAddress; } public RpcProxy(ServiceDiscovery serviceDiscovery) { this.serviceDiscovery = serviceDiscovery; } @SuppressWarnings("unchecked") public <T> T create(Class<?> interfaceClass) { return (T) Proxy.newProxyInstance( interfaceClass.getClassLoader(), new Class<?>[]{interfaceClass}, new InvocationHandler() { public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { RpcRequest request = new RpcRequest(); // 创建并初始化 RPC 请求 request.setRequestId(UUID.randomUUID().toString()); request.setClassName(method.getDeclaringClass().getName()); request.setMethodName(method.getName()); request.setParameterTypes(method.getParameterTypes()); request.setParameters(args); if (serviceDiscovery != null) { serverAddress = serviceDiscovery.discover(); // 发现服务 } String[] array = serverAddress.split(":"); String host = array[0]; int port = Integer.parseInt(array[1]); RpcClient client = new RpcClient(host, port); // 初始化 RPC 客户端 RpcResponse response = client.send(request); // 通过 RPC 客户端发送 RPC 请求并获取 RPC 响应 if (response.getError() != null) { throw response.getError(); } else { return response.getResult(); } } } ); } }listen-rpc-client工程客户端类RpcClient
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package com.listen.rpc.client; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.listen.rpc.common.RpcDecoder; import com.listen.rpc.common.RpcEncoder; import com.listen.rpc.common.RpcRequest; import com.listen.rpc.common.RpcResponse; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelOption; import io.netty.channel.EventLoopGroup; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioSocketChannel; public class RpcClient extends SimpleChannelInboundHandler<RpcResponse> { private static final Logger LOGGER = LoggerFactory.getLogger(RpcClient.class); private String host; private int port; private RpcResponse response; private final Object obj = new Object(); public RpcClient(String host, int port) { this.host = host; this.port = port; } @Override public void channelRead0(ChannelHandlerContext ctx, RpcResponse response) throws Exception { this.response = response; synchronized (obj) { obj.notifyAll(); // 收到响应，唤醒线程 } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { LOGGER.error("client caught exception", cause); ctx.close(); } public RpcResponse send(RpcRequest request) throws Exception { EventLoopGroup group = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap.group(group).channel(NioSocketChannel.class) .handler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel channel) throws Exception { channel.pipeline() .addLast(new RpcEncoder(RpcRequest.class)) // 将 RPC 请求进行编码（为了发送请求） .addLast(new RpcDecoder(RpcResponse.class)) // 将 RPC 响应进行解码（为了处理响应） .addLast(RpcClient.this); // 使用 RpcClient 发送 RPC 请求 } }) .option(ChannelOption.SO_KEEPALIVE, true); ChannelFuture future = bootstrap.connect(host, port).sync(); future.channel().writeAndFlush(request).sync(); synchronized (obj) { obj.wait(); // 未收到响应，使线程等待 } if (response != null) { future.channel().closeFuture().sync(); } return response; } finally { group.shutdownGracefully(); } } }listen-rpc-client工程服务发现类ServiceDiscovery
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package com.listen.rpc.client; import java.io.IOException; import java.util.ArrayList; import java.util.List; import java.util.concurrent.CountDownLatch; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.listen.rpc.common.Constant; import io.netty.util.internal.ThreadLocalRandom; public class ServiceDiscovery { private static final Logger LOGGER = LoggerFactory.getLogger(ServiceDiscovery.class); private CountDownLatch latch = new CountDownLatch(1); private volatile List<String> dataList = new ArrayList<String>(); private String registryAddress; public ServiceDiscovery(String registryAddress) { this.registryAddress = registryAddress; ZooKeeper zk = connectServer(); if (zk != null) { watchNode(zk); } } public String discover() { String data = null; int size = dataList.size(); if (size > 0) { if (size == 1) { data = dataList.get(0); LOGGER.debug("using only data: {}", data); } else { data = dataList.get(ThreadLocalRandom.current().nextInt(size)); LOGGER.debug("using random data: {}", data); } } return data; } private ZooKeeper connectServer() { ZooKeeper zk = null; try { zk = new ZooKeeper(registryAddress, Constant.ZK_SESSION_TIMEOUT, new Watcher() { public void process(WatchedEvent event) { if (event.getState() == Event.KeeperState.SyncConnected) { latch.countDown(); } } }); latch.await(); } catch (IOException e) { LOGGER.error("", e); } catch (InterruptedException e){ LOGGER.error("", e); } return zk; } private void watchNode(final ZooKeeper zk) { try { List<String> nodeList = zk.getChildren(Constant.ZK_REGISTRY_PATH, new Watcher() { public void process(WatchedEvent event) { if (event.getType() == Event.EventType.NodeChildrenChanged) { watchNode(zk); } } }); List<String> dataList = new ArrayList<String>(); for (String node : nodeList) { byte[] bytes = zk.getData(Constant.ZK_REGISTRY_PATH + "/" + node, false, null); dataList.add(new String(bytes)); } LOGGER.debug("node data: {}", dataList); this.dataList = dataList; } catch (KeeperException e) { e.printStackTrace(); LOGGER.error("", e); } catch (InterruptedException e){ LOGGER.error("", e); } } }listen-rpc-client工程配置文件config.properties
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# ZooKeeper 服务器 registry.address=127.0.0.1:2181 #以上配置表明：连接本地的 ZooKeeper 服务器，并在 8000 端口上发布 RPC 服务。listen-rpc-client工程spring.xml配置文件
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd"> <!-- 启用spring mvc 注解 --> <context:annotation-config /> <!-- 完成请求和注解POJO的映射 --> <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" /> <!-- 对转向页面的路径解析。prefix：前缀， suffix：后缀 --> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> <context:component-scan base-package="com.listen.rpc" /> <context:property-placeholder location="classpath:config.properties"/> <!-- 配置服务发现组件 --> <bean id="serviceDiscovery" class="com.listen.rpc.client.ServiceDiscovery"> <constructor-arg name="registryAddress" value="${registry.address}"/> </bean> <!-- 配置 RPC 代理 --> <bean id="rpcProxy" class="com.listen.rpc.client.RpcProxy"> <constructor-arg name="serviceDiscovery" ref="serviceDiscovery"/> </bean> </beans>
至此，客户端代码编写完毕，接下来就是测试了
测试服务接口
- 启动服务端 tomcat7:run；勾选Skip test
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- 启动客户端 tomcat7:run；勾选Skip test
- 访问地址测试
- http://localhost:8080/hello?name=aaa 返回helloaaa
- http://localhost:8080/getUser?name=aaa 返回{"birthday":1464258865975,"name":"aaa","sex":true}
- http://localhost:8080/getUsers?size=5 返回{"birthday":1464345304049,"name":"foo","sex":true}
{"birthday":1464431704049,"name":"foo","sex":false}
{"birthday":1464518104049,"name":"foo","sex":true}
{"birthday":1464604504049,"name":"foo","sex":false}
{"birthday":1464690904049,"name":"foo","sex":true} - http://localhost:8080/updateUser?name=kaka 返回{"birthday":1464258949048,"name":"kaka-update","sex":true}
至此说明服务可以正常发布及调用。
需要注意的点为Zookeeper数据地址的获取，可参考 Windows下Zookeeper的简单配置。
工程源码地址：
https://git.oschina.net/git.listen/listen-parent
https://git.oschina.net/git.listen/listen-rpc-common
https://git.oschina.net/git.listen/listen-rpc-server
https://git.oschina.net/git.listen/listen-rpc-service
https://git.oschina.net/git.listen/listen-rpc-service-impl
https://git.oschina.net/git.listen/listen-rpc-client
来源：oschina
链接：https://my.oschina.net/u/39617/blog/682124