第一个dubbo程序

Dubbo是阿里SOA服务化治理方案的核心框架，它提供了注册中心机制，解耦了消费方和服务方动态发现的问题，并提供高可靠能力，大量采用为内核+富插件设计思想，包括框架自身核心特性都作为扩展点实现，提供灵活的可扩展能力。

Dubbo架构

上图是Dubbo的架构图，其中Provider在启动时会向注册中心把自己的元数据注册上去（比如服务IP和端口等），Consumer在启动时从注册中心订阅（第一次订阅会拉取全量数据）服务提供方的元数据，注册中心发生数据变更会推送给订阅的Consumer。在获取服务元数据后，Consumer可以发起RPC调用，在RPC调用前后会向监控中心上报统计信息（比如并发数和调用的接口）。

下面我们就使用Dubbo搭建一个简单的Demo。

安装Zookeeper

从Zookeeper的官网下载Zookeeper的安装包，解压到任意目录，作为安装目录install_directory

新建环境变量ZK_HOME，指向${install_directory}/

将${ZK_HOME}/bin路径，添加到可执行路径

在${ZK_HOME}/conf路径下复制一份配置文件zoo_sample.cfg，并重命名为zoo.cfg

在终端执行zkServer.sh start即可，默认会监听2181端口。

第一个dubbo程序

新建一个Maven项目，依赖为：

<dependencies>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.3</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-rpc-rest</artifactId>
            <version>2.6.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>2.12.0</version>
        </dependency>
    </dependencies>

然后新建三个子模块：

first-dubbo-service：对外暴露的服务，所有对外暴露的接口，都在这边
first-dubbo-server：first-dubbo-service的实现方，实现了first-dubbo-service暴露的接口
first-dubbo-client：服务调用方

基于XML配置实现

first-dubbo-service

首先声明一个HelloService接口，提供一个hello方法

public interface HelloService {

    public String hello(String name);
}

first-dubbo-server

定义一个HelloService的实现类，实现了HelloService的hello方法

public class HelloServiceImpl implements HelloService {
    public String hello(String name) {
        String now = new SimpleDateFormat("HH:mm:ss").format(new Date());
        return "Hello, " + name + ", now is " + now + ", request from " + RpcContext.getContext().getRemoteAddressString();
    }
}

接着编写一个启动类，它做的主要是从指定的XML配置文件中读取配置，并启动

public class HelloServerApplication {

    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"spring/hello-server.xml"});
        context.start();
        System.in.read();
    }

}

spring/hello-server.xml配置文件内容为：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- 服务提供方应用名称, 方便用于依赖跟踪 -->
    <dubbo:application name="hello-server"/>

    <!-- 使用本地zookeeper作为注册中心 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>

    <!-- 只用Dubbo协议并且指定监听端口 20880 -->
    <dubbo:protocol name="dubbo" port="20880"/>

    <!-- 通过xml方式配置为bean, 让spring托管和实例化 -->
    <bean id="helloService" class="com.dubbo.service.impl.HelloServiceImpl"/>

    <!-- 声明服务暴露的接口，并暴露服务 -->
    <dubbo:service interface="com.dubbo.service.HelloService" ref="helloService"/>

</beans>

启动完成之后，打开XShell，执行命令telnet localhost 20880连接上dubbo。

telnet连接

然后输入invoke com.dubbo.service.HelloService.hello("huhansan")发起调用，调用的格式为invoke [接口.fangfa ]

invoke调用接口方法

上图为调用成功，标明Server服务成功启动，并且成功响应了调用。

first-dubbo-client

client的启动代码如下：

public class HelloClientApplication {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"spring/hello-client.xml"});
        context.start();
        HelloService helloService = (HelloService) context.getBean("helloService");
        String result = helloService.hello("huhansan");
        System.out.println("Call hello result is " + result);
    }
}

其中spring/hello-client.xml配置为：

<?xml version="1.0" encoding="UTF-8"?>
<!--
  ~
  ~   Licensed to the Apache Software Foundation (ASF) under one or more
  ~   contributor license agreements.  See the NOTICE file distributed with
  ~   this work for additional information regarding copyright ownership.
  ~   The ASF licenses this file to You under the Apache License, Version 2.0
  ~   (the "License"); you may not use this file except in compliance with
  ~   the License.  You may obtain a copy of the License at
  ~
  ~       http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~   Unless required by applicable law or agreed to in writing, software
  ~   distributed under the License is distributed on an "AS IS" BASIS,
  ~   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~   See the License for the specific language governing permissions and
  ~   limitations under the License.
  ~
  -->

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- 服务消费方应用名称, 方便用于依赖跟踪 -->
    <dubbo:application name="hello-client"/>

    <!-- 使用本地zookeeper作为注册中心 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181"/>

    <!-- 声明服务暴露的接口，并暴露服务 -->
    <dubbo:reference id="helloService" check="false" interface="com.dubbo.service.HelloService"/>

</beans>

运行消费方的方法可得结果：

Client调用结果

基于注解实现

所有依赖保持不变。

first-dubbo-server

HelloService实现类修改为：

@Service
public class HelloServiceAnnotationImpl implements HelloService {
    public String hello(String name) {
        String now = new SimpleDateFormat("HH:mm:ss").format(new Date());
        return "Hello, " + name + ", now is " + now + ", request from " + RpcContext.getContext().getRemoteAddressString();
    }
}

在类上使用注解@Service标记

HelloServerApplication修改为：

public class HelloServerAnnotationApplication {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(HelloServerConfig.class);
    }

    @Configuration
    // 指定扫描服务所在的包的路径
    @EnableDubbo(scanBasePackages = "com.dubbo.service")
    static class HelloServerConfig {

        @Bean
        public ProviderConfig providerConfig() {
            return providerConfig();
        }

        @Bean
        public ApplicationConfig applicationConfig() {
            ApplicationConfig config = new ApplicationConfig();
            config.setName("hello-client");
            return config;
        }

        @Bean
        public RegistryConfig registryConfig() {
            RegistryConfig registryConfig = new RegistryConfig();
            // 使用Zookeeper的注册中心，同时给出注册中心的IP和端口
            registryConfig.setProtocol("zookeeper");
            registryConfig.setAddress("localhost");
            registryConfig.setPort(2181);
            return registryConfig;
        }

        public ProtocolConfig protocolConfig() {
            ProtocolConfig protocolConfig = new ProtocolConfig();
            // 默认使用Dubbo服务，在20880端口监听服务
            protocolConfig.setName("dubbo");
            protocolConfig.setPort(20880);
            return protocolConfig;
        }
    }

}

first-dubbo-client

HelloClientApplication修改为：

public class HelloClientAnnotationApplication {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(HelloClientConfig.class);
        context.start();
        HelloClientAnnotation helloService = context.getBean(HelloClientAnnotation.class);
        String result = helloService.hello("huhansi");
        System.out.println("Result is " + result);
    }

    @Configuration
    @EnableDubbo(scanBasePackages = "com.dubbo.service")
    @ComponentScan(value = {"com.dubbo.client"})
    static class HelloClientConfig {
        @Bean
        public ApplicationConfig applicationConfig() {
            ApplicationConfig config = new ApplicationConfig();
            config.setName("hello-client");
            return config;
        }

        @Bean
        public ConsumerConfig consumerConfig() {
            return new ConsumerConfig();
        }

        @Bean
        public RegistryConfig registryConfig() {
            RegistryConfig registryConfig = new RegistryConfig();
            registryConfig.setProtocol("zookeeper");
            registryConfig.setAddress("localhost");
            registryConfig.setPort(2181);
            return registryConfig;
        }

    }

}

新增一个HelloClientAnnotation类：

@Component
public class HelloClientAnnotation {
    @Reference
    private HelloService helloService;

    public String hello(String name) {
        return helloService.hello(name);
    }
}

通过注解消费服务时，只需要@Reference注解标注，该注解适用于对象字段和方法中。因此需要做一下特殊的包装。

基于代码实现

所有依赖保持不变

first-dubbo-server

HelloServerApplication修改为：

public class HelloServerApiApplication {

    public static void main(String[] args) throws Exception {
        ServiceConfig<HelloService> service = new ServiceConfig<HelloService>();
        service.setApplication(new ApplicationConfig("hello-server"));
        service.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
        service.setInterface(HelloService.class);
        service.setRef(new HelloServiceImpl());
        service.export();
        System.out.println("Hello Server is running.");
        System.in.read();
    }

}

first-dubbo-client

HelloClientApplication修改为：

public class HelloClientApiApplication {

    public static void main(String[] args) {
        ReferenceConfig<HelloService> reference = new ReferenceConfig<HelloService>();
        reference.setApplication(new ApplicationConfig("hello-client"));
        reference.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
        reference.setInterface(HelloService.class);
        HelloService helloService = reference.get();
        String result = helloService.hello("huhanwu");
        System.out.println("Result is " + result);
    }

}