Dubbo 入门教程与实战（一）上

dubbo前言

dubbo学习网址

项目dubbo-demo实战篇

（实战一）dubbo-demo-api定义

（实战二）dubbo-demo-provider实现

（实战三）dubbo-demo-consumer实现

dubbo-demo资源下载

本篇实战总结

dubbo前言

Dubbo是高性能的，基于java的RPC框架，RPC框架之前的文章有讲过可以看一下。

dubbo学习网址

官网：http://dubbo.io/
中文网：http://dubbo.apache.org/zh-cn/

进不去请点击中文网，快速开发

项目dubbo-demo实战篇

1）先创建如图所示的项目结构【接口、服务提供者、消费者】

2）dubbo-demo/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.imooc</groupId><artifactId>dubbo-demo</artifactId><packaging>pom</packaging><version>1.0-SNAPSHOT</version><modules><module>dubbo-demo-provider</module><module>dubbo-demo-api</module><module>dubbo-demo-consumer</module></modules><properties><maven.compiler.source>1.7</maven.compiler.source><maven.compiler.target>1.7</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><!-- spring版本号 --><spring.version>4.2.5.RELEASE</spring.version><!-- log4j日志包版本号 --><slf4j.version>1.7.18</slf4j.version><log4j.version>1.2.17</log4j.version></properties><dependencies><!-- 添加spring核心依赖 --><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId><version>${spring.version}</version></dependency><!-- spring 结束 --><!-- 添加日志相关jar包 --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>${log4j.version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>${slf4j.version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>${slf4j.version}</version></dependency><!-- log end --><!-- zeekeeper注册中心 --><dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.4.9</version></dependency><dependency><groupId>com.101tec</groupId><artifactId>zkclient</artifactId><version>0.10</version></dependency><!-- dubbo --><dependency><groupId>com.alibaba</groupId><artifactId>dubbo</artifactId><version>2.5.3</version><exclusions><exclusion><groupId>org.springframework</groupId><artifactId>spring</artifactId></exclusion></exclusions></dependency></dependencies>
</project>

（实战一）dubbo-demo-api定义

根据快速文档新增 dubbo-demo/dubbo-demo-api/src/main/java/org/apache/dubbo/demo/DemoService.java

package org.apache.dubbo.demo;/*** @Description : api* @Auth : Xuhy* @Date : 2019-02-04* @Time : 21:58*/
public interface DemoService {String sayHello(String name);
}

修改 dubbo-demo/dubbo-demo-api/pom.xml 文件内容，如图所示

具体 pom.xml 如下

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><artifactId>dubbo-demo-api</artifactId><groupId>com.imooc</groupId><version>1.0-SNAPSHOT</version>
</project>

（实战二）dubbo-demo-provider实现

Implement service provider

1）根据快速开发文档，创建服务实现类DemoServiceImpl

package org.apache.dubbo.demo.provider;import org.apache.dubbo.demo.DemoService;/*** @Description : 在服务提供方实现接口* @Auth : Xuhy* @Date : 2019-02-04* @Time : 22:14*/
public class DemoServiceImpl implements DemoService {@Overridepublic String sayHello(String name) {return "Hello " + name;}
}

Configure service provider

1.1 配置篇 resource/dubbo-provider.xml（值得注意的是将快速开发的provider.xml直接粘贴过来会报错误！！！找不到配置文件。无论你用什么读法就是读不到，所以将原先的配置文件部分修改如下所示。。。）

<?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/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://code.alibabatech.com/schema/dubbohttp://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="hello-world-app"/><!--使用 zookeeper 注册中心暴露服务，注意要先开启 zookeeper--><dubbo:registry address="zookeeper://localhost:2181"/><!-- 使用multicast广播注册中心暴露服务地址 --><!--<dubbo:registry address="multicast://224.5.6.7:1234"/>--><!-- 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="org.apache.dubbo.demo.DemoService" ref="demoService"/><!-- 和本地bean一样实现服务 --><bean id="demoService" class="org.apache.dubbo.demo.provider.DemoServiceImpl"/>
</beans>

1.2 配置篇新增log4j（resource/log4j.xml）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false"><appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender"><layout class="org.apache.log4j.PatternLayout"><param name="ConversionPattern" value="[%d{dd/MM/yy hh:mm:ss:sss z}] %t %5p %c{2}: %m%n" /></layout></appender><root><level value="INFO" /><appender-ref ref="CONSOLE" /></root>
</log4j:configuration>

Start service provider（准备一个启动类）

3.1）导入对应pom文件，支持ClassPathXmlApplicationContext.class，如果是这个class报错再导入

<!-- 导入pom文件jar -->
<!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>4.3.14.RELEASE</version>
</dependency>

3.2）编写启动类MainProvider

package org.apache.dubbo.demo.provider;import org.springframework.context.support.ClassPathXmlApplicationContext;/*** @Description : Start service provider* @Auth : Xuhy* @Date : 2019-02-04* @Time : 22:23*/
public class MainProvider {public static void main(String[] args) throws Exception {ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("dubbo-provider.xml");context.start();System.err.print("启动成功！"); // 按任意键退出System.in.read(); // 按任意键退出}
}

3）启动篇

3.1 如果使用Intellij Idea 广播模式：请加上-Djava.net.preferIPv4Stack=true，也可以利用zookeeper启动

zookeeper3.4.10下载地址：https://mirrors.cnnic.cn/apache/zookeeper/zookeeper-3.4.10/（解压到本地，并进入其conf目录，重命名zoo_sample.cfg为zoo.cfg即可，其余无需改动。windows启动方式：zookeeper-3.4.10/bin下的zkServer）

3.2 run MainProvider.java

（实战三）dubbo-demo-consumer实现

Consumer.java

package com.alibaba.dubbo.consumer;import org.apache.dubbo.demo.DemoService;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** @Description : 加载Spring配置，并调用远程服务* @Auth : Xuhy* @Date : 2019-02-06* @Time : 17:37*/
public class Consumer {public static void main(String[] args) throws Exception {ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("consumer.xml");context.start();System.err.println("consumer start");DemoService demoService = (DemoService)context.getBean("demoService"); // 获取远程服务代理String hello = demoService.sayHello("world"); // 执行远程方法System.out.println( hello ); // 显示调用结果}
}

配置篇 resource/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:dubbo="http://code.alibabatech.com/schema/dubbo"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://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="consumer-of-helloworld-app"  /><!--向 zookeeper 订阅 provider 的地址，由 zookeeper 定时推送--><dubbo:registry address="zookeeper://localhost:2181"/><!-- 使用multicast广播注册中心暴露发现服务地址 --><!--<dubbo:registry address="multicast://224.5.6.7:1234" />--><!-- 生成远程服务代理，可以和本地bean一样使用demoService --><dubbo:reference id="demoService" interface="org.apache.dubbo.demo.DemoService" />
</beans>

配置篇 resource/log4j.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false"><appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender"><layout class="org.apache.log4j.PatternLayout"><param name="ConversionPattern" value="[%d{dd/MM/yy hh:mm:ss:sss z}] %t %5p %c{2}: %m%n" /></layout></appender><root><level value="INFO" /><appender-ref ref="CONSOLE" /></root>
</log4j:configuration>

dubbo-demo资源下载

下载地址：正在审核中。。。。。

本篇实战总结

遇见问题：

1、加载不出来配置信息，我将provider和consumer的xml文件除了log4j都修改了；

2、启动偶而不成功问题，如果你用了zookeeper启动，都要用它来启动，不能一个广播一个zookeeper；

3、都用广告启动不成功问题，这个我也遇见了，provider用广播，consumer也用广播，启动不成功！不知道为啥，也配置了Vm option，没有用！

所以上面的案例全部修改为zookeeper启动