Dubbo 学习1 快速开始

简介

Dubbo是Alibaba开源的分布式服务框架，它最大的特点是按照分层的方式来架构，使用这种方式可以使各个层之间解耦合（或者最大限度地松耦合）。从服务模型的角度来看，Dubbo采用的是一种非常简单的模型，要么是提供方提供服务，要么是消费方消费服务，所以基于这一点可以抽象出服务提供方（Provider）和服务消费方（Consumer）两个角色。

官网：​​http://dubbo.io/​​​ GIT地址：​​https://github.com/alibaba/dubbo​​ 用户手册：​​http://dubbo.apache.org/​​

Dubbo的架构：

开始

• JDK: version 6 or higher
• Maven: version 3 or higher

项目结构：
provider

consumer

Maven

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>dubbo</artifactId>
    <version>2.5.7</version>
</dependency>

Provider

定义服务接口
建议将接口定义在客户端、服务端公用的模块里。

package com.alibaba.dubbo.demo;

public interface DemoService {
    String sayHello(String name);
}

实现

package com.alibaba.dubbo.demo.provider;
import com.alibaba.dubbo.demo.DemoService;

public class DemoServiceImpl implements DemoService {
    public String sayHello(String name) {
        return "Hello " + name;
    }
}

配置服务生产者

<?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="demo-provider"/>
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <dubbo:protocol name="dubbo" port="20880"/>
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService"/>
    <bean id="demoService" class="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>
</beans>

启动生产者

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[] {"dubbo-demo-provider.xml"});
        context.start();
        System.in.read(); // press any key to exit
    }
}

Consumer

配置消费者

<?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="demo-consumer"/>
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <dubbo:reference id="demoService" interface="com.alibaba.dubbo.demo.DemoService"/>
</beans>

执行

import com.alibaba.dubbo.demo.DemoService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Consumer {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[]{"dubbo-demo-consumer.xml"});
        context.start();
        DemoService demoService = (DemoService) context.getBean("demoService"); // obtain proxy object for remote invocation
        String hello = demoService.sayHello("world"); // execute remote invocation
        System.out.println(hello); // show the result
    }
}

运行结果：

一些问题处理

dubbo 使用logback

<dependency>
        <groupId>com.github.sgroschupf</groupId>
        <artifactId>zkclient</artifactId>
        <version>0.1</version>
        <exclusions>
            <exclusion>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
            </exclusion>
        </exclusions>
 </dependency>
 <!--zkClient和disconf都会依赖zookeeper,而zookeeper会依赖slf4j-log4j12和log4j,
 在我们使用logback的情况下，需要将log4j转为logback，则需依赖log4j-over-slf4j。
 slf4j-log4j12会与log4j-over-slf4j循环依赖导致冲突，
 所以所有依赖zookeeper的jar必须exclude掉slf4j-log4j12-->
<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>${zookeeper.version}</version>
    <exclusions>
        <exclusion>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </exclusion>
        <!--
        https://issues.apache.org/jira/browse/ZOOKEEPER-1371
        zookeeper Remove dependency on log4j in the source code.
        slf4j-log4j12会与log4j-over-slf4j循环依赖导致冲突
        -->
        <exclusion>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>log4j-over-slf4j</artifactId>
</dependency>

在logback.xml里写上：

<logger name="com.alibaba.dubbo" level="DEBUG"/>

在dubbo的配置文件里写：

<dubbo:application name="controlservice-rpc-provider" logger="slf4j">