dubbo学习(1)--简单的入门搭建实例

    转载请注明源文出处：http://www.cnblogs.com/lighten/p/6828026.html

1 简介

    dubbo是一个分布式服务框架，由阿里巴巴的工程师开发，致力于提供高性能和透明化的RPC远程服务调用。可惜的是该项目在2012年之后就没有再更新了，之后由当当基于dubbo开发了dubbox。这里对dubbo的入门构建进行简单的介绍。不涉及dubbo的运行机制，只是搭建过程，方便学习者快速构建项目，运行、熟悉该框架。

    dubbo提供了两种构建项目的方法。1.通过Spring容器快速构建，其中还有注解的方式；2.通过直接使用API（不推荐）。以下对其一一说明。

2 前期工作

    创建一个普通的maven项目，导入dubbo的依赖：

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>dubbo</artifactId>
    <version>2.5.3</version>
</dependency>

<dependency>
     <groupId>com.101tec</groupId>
     <artifactId>zkclient</artifactId>
     <version>0.4</version>
 </dependency>

    下载zookeeper作为注册中心，具体步骤参考这里。

3 Spring配置方式

3.1 生产者Provider

    dubbo的生产者是用于提供服务的，先定义服务接口和服务的实现类：

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public interface DemoService {          public String greet(String name);     public List<User> getUsers();      }

    这里有两个服务一个是输入一个字符串，一个是返回一个一个List对象，User类的内容如下：

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public class User implements Serializable{           private static final long serialVersionUID = 1L;           private String name;     private int age;     private String sex;       public User(String name, int age, String sex) {         this.name = name;         this.age = age;         this.sex = sex;     }           public String getName() {         return name;     }     public void setName(String name) {         this.name = name;     }     public int getAge() {         return age;     }     public void setAge(int age) {         this.age = age;     }     public String getSex() {         return sex;     }     public void setSex(String sex) {         this.sex = sex;     }       @Override     public String toString() {         return "User [name=" + name + ", age=" + age + ", sex=" + sex + "]";     } }

     由于接口中会传递一个List的User对象，所以User需要实现Serializable接口。下面是DemoServiceImpl，接口的实现类中的内容：

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public class DemoServiceImpl implements DemoService{       @Override     public String greet(String name) {         return "Hello " + name;     }       @Override     public List<User> getUsers() {         List<User> list = new ArrayList<User>();                   User user1 = new User("张三",10,"男");         User user2 = new User("李四",11,"女");         User user3 = new User("王五",12,"男");                   list.add(user1);         list.add(user2);         list.add(user3);                   return list;     }   }

     这就是一个简单的生产者提供的服务了，和普通的服务类没有什么区别，关键是下面的dubbo配置了。与Spring结合，需要一个dubbo的配置xml文件，我命名为provider.xml，里面的内容如下：

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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:dubbo="http://code.alibabatech.com/schema/dubbo"     xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd     http://code.alibabatech.com/schema/dubbo     http://code.alibabatech.com/schema/dubbo/dubbo.xsd">           <!-- 服务bean -->     <bean id="demoService" class="com.xxx.dubbo.service.impl.DemoServiceImpl" />       <dubbo:application name="provider" />           <dubbo:registry address="zookeeper://127.0.0.1:2181" />           <dubbo:protocol name="dubbo" port="20886" payload="16777216"/>           <dubbo:service interface="com.xxx.dubbo.service.DemoService" ref="demoService" /> </beans>

     上面的XML配置文件就将服务暴露出去了，将其注册到了zookeeper中。最后运行Spring，测试：

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public class Provider {       public static void main(String[] args) throws IOException {         ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"provider.xml"});         context.start();         System.in.read();     } }

    控制台输出日志如下，就可以了：

3.2 消费者

    消费者的配置就更加简单了，其只需要想要调用的服务的接口，在这里就是DemoService接口，注意要确保是同一个接口。然后配置消费者的consumer.xml，配置如下：

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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:dubbo="http://code.alibabatech.com/schema/dubbo"     xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd     http://code.alibabatech.com/schema/dubbo     http://code.alibabatech.com/schema/dubbo/dubbo.xsd">           <dubbo:application name="consumer"/>           <dubbo:registry address="zookeeper://127.0.0.1:2181"/>           <dubbo:reference id="demoService" interface="com.xxx.dubbo.service.DemoService" /> </beans>

     reference就代表着引用一个服务，从暴露服务注册的注册中心获取，在spring中就有一个这样的接口实例了。测试类：

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public class Consumer {       public static void main(String[] args) {         ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"consumer.xml"});         context.start();                   DemoService demoService = (DemoService) context.getBean("demoService");         System.out.println(demoService.greet("张三"));         System.out.println(demoService.getUsers());     } }

     开启刚刚的生产者测试类，再运行这个消费者测试类，就会看到打印出：

 3.3 注解方式

　　注解的方式配置起来非常的简单，全部如下：

　　生产者就是实现类上打上@Service注解就可以了，注意这个注解是com.alibaba.dubbo.config.annotation.Service，不是Spring的Service注解。

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@Service public class AnnotationProvider implements DemoService{       @Override     public String greet(String name) {         return "Hello " + name;     }       @Override     public List<User> getUsers() {         List<User> list = new ArrayList<User>();                   User user1 = new User("张三",10,"男");         User user2 = new User("李四",11,"女");         User user3 = new User("王五",12,"男");                   list.add(user1);         list.add(user2);         list.add(user3);                   return list;     } }

     配置文件也就是去掉了bean和<dubbo:service>，使用<dubbo:annotation>取代了：

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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:dubbo="http://code.alibabatech.com/schema/dubbo"     xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd     http://code.alibabatech.com/schema/dubbo     http://code.alibabatech.com/schema/dubbo/dubbo.xsd">             <dubbo:application name="provider" />           <dubbo:registry address="zookeeper://127.0.0.1:2181" />           <dubbo:protocol name="dubbo" port="20886" payload="16777216"/>           <dubbo:annotation package="com.xxx.dubbo.spring.annotation.provider"/> </beans>

     消费者也相差无几：

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@Service public class AnnotationComsumer {       @Reference(check=false)     private DemoService demoService;           public void print() {         System.out.println(demoService.greet("张三"));         System.out.println(demoService.getUsers());     }   }

     注意这个Service是Spring的注解。配置文件如下：

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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:dubbo="http://code.alibabatech.com/schema/dubbo"     xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans.xsd     http://code.alibabatech.com/schema/dubbo     http://code.alibabatech.com/schema/dubbo/dubbo.xsd">           <dubbo:application name="consumer"/>           <dubbo:registry address="zookeeper://127.0.0.1:2181"/>           <dubbo:annotation package="com.xxx.dubbo.spring.annotation.consumer" /> </beans>

     启动程序如下：

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public static void main(String[] args) throws IOException {     ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"annotation-provider.xml"});     context.start();     System.in.read(); }   public static void main(String[] args) {         ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"annotation-consumer.xml"});         context.start();         AnnotationComsumer demoService =  (AnnotationComsumer) context.getBean("annotationComsumer");         demoService.print(); }

     最终效果和之前的一样。

4. API配置方式

    这个简单说明一下，其实看API的方式和配置文件的方式就会明白一些，不做详细介绍。

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public class APIProvider {       public static boolean running = true;           public static void main(String[] args) {           DemoService demoService = new DemoServiceImpl();                   ApplicationConfig applicationConfig =  new ApplicationConfig();         applicationConfig.setName("provider");                   RegistryConfig registryConfig = new RegistryConfig();         registryConfig.setAddress("zookeeper://127.0.0.1:2181");                   ProtocolConfig protocolConfig = new ProtocolConfig();         protocolConfig.setName("dubbo");         protocolConfig.setPort(20886);         protocolConfig.setPayload(16*1024*1024);                   ServiceConfig<DemoService> service = new ServiceConfig<DemoService>();                   service.setApplication(applicationConfig);         service.setRegistry(registryConfig);         service.setProtocol(protocolConfig);         service.setInterface(DemoService.class);         service.setRef(demoService);                   service.export();                   Runtime.getRuntime().addShutdownHook(new Thread() {             public void run() {                 synchronized (APIProvider.class) {                     running = false;                     APIProvider.class.notify();                 }             }         });                   synchronized(APIProvider.class) {             while(running) {                 try {                     APIProvider.class.wait();                 } catch (Throwable e) {                 }             }         }     } }

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public class APIConsumer {           public static void main(String[] args) {           ApplicationConfig applicationConfig =  new ApplicationConfig();         applicationConfig.setName("consumer");                     RegistryConfig registryConfig = new RegistryConfig();         registryConfig.setAddress("zookeeper://127.0.0.1:2181");                   ReferenceConfig<DemoService> reference = new ReferenceConfig<DemoService>();         reference.setApplication(applicationConfig);         reference.setRegistry(registryConfig);         reference.setInterface(DemoService.class);                   DemoService demoService = reference.get();         System.out.println(demoService.greet("李四"));         System.out.println(demoService.getUsers());     } }

     都是要先定义ApplicationConfig和<dubbo:application>一致，后面RegistryConfig也一样<dubbo:registry>。具体过程之后篇章介绍。这种API的方法不被推荐使用。

5 后记

    本篇主要是帮助新手快速入门搭建一个dubbo服务，之后会从整体结构上介绍一下dubbo是如何工作的，再往后会讲解一下源码实现。水平有限，有错请指教。