Dubbo入门

架构

dubbo-architecture.jpg
节点角色.png
调用关系说明

1. 服务容器负责启动，加载，运行服务提供者。
2. 服务提供者在启动时，向注册中心注册自己提供的服务。
3. 服务消费者在启动时，向注册中心订阅自己所需的服务。
4. 注册中心返回服务提供者地址列表给消费者，如果有变更，注册中心将基于长连接推送变更数据给消费者。
5. 服务消费者，从提供者地址列表中，基于软负载均衡算法，选一台提供者进行调用，如果调用失败，再选另一台调用。
6. 服务消费者和提供者，在内存中累计调用次数和调用时间，定时每分钟发送一次统计数据到监控中心。

入门例子

准备：
导包：zookeeper包、dubbo包、curator-framework包等
启动注册中心zookeeper

zk.png

功能：web层调用service层提供的查询用户是否存在的接口
dubbo-provider.xml：

<?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: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://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context.xsd
        http://code.alibabatech.com/schema/dubbo 
        http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <!-- 提供方应用信息，用于计算依赖关系 -->
    <dubbo:application name="sunpy-service"  />
 
    <!-- 使用multicast广播注册中心暴露服务地址 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181" />
 
    <!-- 用dubbo协议在20880端口暴露服务 -->
    <dubbo:protocol name="dubbo" port="20880" />
 
    <!-- 声明需要暴露的服务接口 -->
    <dubbo:service interface="cn.spy.single.service.UserService" ref="userService" timeout="600000"/>
</beans>

spring.xml：

<?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:beans="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans   
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd  
    http://www.springframework.org/schema/context  
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
    
    <beans:import resource="classpath:spring-mybatis.xml"/>
    <beans:import resource="classpath:dubbo-provider.xml"/>
    <context:property-placeholder location="classpath:/config.properties" />
    <context:property-placeholder location="classpath:/log4j.properties" />
    <context:component-scan base-package="cn.spy"></context:component-scan>
    
</beans>

提供者：

public class ServiceProvider {
    
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"spring.xml"});  
        context.start();  
        // 为保证服务一直开着，利用输入流的阻塞来模拟
        System.in.read();  
    }
}

---

dubbo-consumer.xml：

<?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: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://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context.xsd
        http://code.alibabatech.com/schema/dubbo 
        http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <!-- 消费方应用名，用于计算依赖关系，不是匹配条件，不要与提供方一样 -->
    <dubbo:application name="sunpy-web"  />
 
    <!-- 使用multicast广播注册中心暴露发现服务地址 -->
    <dubbo:registry address="zookeeper://127.0.0.1:2181" />
 
    <!-- 生成远程服务代理，可以和本地bean一样使用demoService -->
    <dubbo:reference id="userService" interface="cn.spy.single.service.UserService" />
</beans>

spring.xml：

<?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:beans="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans   
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd  
    http://www.springframework.org/schema/context  
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
    
    <beans:import resource="classpath:dubbo-consumer.xml"/>
    <context:property-placeholder location="classpath:/log4j.properties" />
    <context:component-scan base-package="cn.spy"></context:component-scan>

消费者：

public class WebConsumer {
    
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"spring.xml"});
        context.start();
        UserService userService = (UserService) context.getBean("userService"); // 获取远程服务代理
        User user = userService.selectUser("zhangjl01");
        System.out.println(user); // 显示调用结果
    }
}

结果：

result.png