Dubbo 在maven项目中的应用

首先我们来看一下dubbo的架构：

所以通过此图，我们看到就是服务的提供者将服务注册到注册中心，服务的消费者从注册中心获取服务，monitor监控服务的调用。

关于dubbo的使用，我们举个简单的例子：

存在2个系统，A系统和B系统，A系统调用B系统的接口获取数据，用于查询用户列表。

废话不多少，直接构建项目：

构建一个dubbo-ab-api ，此项目包含供其他两个项目使用的POJO类和接口Service类

1、在Eclipse中点检新建项目，选择maven项目后，点击“next”：

2、项目存储位置，点击“next”：

3、因为建立的是“jar”项目，选择“maven-archetype-quickstart”,点击“next”：

4、填写Group ID（项目组织唯一的标识符）和Artifact ID（项目的唯一的标识符）点击“Finish”，完成项目创建。

5、项目创建好后，在项目中增加pojo和service包：

6、在pojo包中添加User.java 类。

package cn.itcast.dubbo.pojo;import java.io.Serializable;public class User implements Serializable {/*** */private static final long serialVersionUID = -8096919250664823274L;private Long id;private String username;private String password;private Integer age;public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}@Overridepublic String toString() {return "User [id=" + id + ", username=" + username + ", password=" + password + ", age=" + age + "]";}}

7、在service包中UserService.java 接口类。

package cn.itcast.dubbo.service;import java.util.List;import cn.itcast.dubbo.pojo.User;public interface UserService {/*** 查询所有的用户数据** @return*/public List<User> queryAll();
}

7、将JAR包安装到本地仓库，供其他Maven项目依赖使用。(如果有maven私仓，则将jar包添加到maven私仓中，供其他项目调用)

创建dubbo-b项目，此项目为web项目，作为服务提供方

1、在Eclipse中点检新建项目，选择maven项目后，点击“next”：

2、项目存储位置，点击“next”：

3、建立web项目，选择“maven-archetype-webapp”，点击“next”：

4、填写Group ID（项目组织唯一的标识符）和Artifact ID（项目的唯一的标识符）点击“Finish”，完成项目创建。

5、项目创建好后，在项目中增加cn.itcast.dubbo.service.impl包：

6、在“pom.xml”导入依赖:

<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>cn.itcast.dubbo</groupId><artifactId>dubbo-b</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>dubbo-b Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.1.3.RELEASE</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.6.4</version></dependency><dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.3.3</version></dependency><dependency><groupId>cn.itcast.dubbo</groupId><artifactId>dubbo-ab-api</artifactId><version>0.0.1-SNAPSHOT</version></dependency><dependency><groupId>com.github.sgroschupf</groupId><artifactId>zkclient</artifactId><version>0.1</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>dubbo</artifactId><version>2.5.3</version><exclusions><exclusion><!-- 排除传递spring依赖 --><artifactId>spring</artifactId><groupId>org.springframework</groupId></exclusion></exclusions></dependency></dependencies><build><plugins><plugin><groupId>org.apache.tomcat.maven</groupId><artifactId>tomcat7-maven-plugin</artifactId><version>2.2</version><configuration><port>8081</port><path>/</path></configuration></plugin></plugins></build>
</project>

7、在cn.itcast.dubbo.service.impl包中创建UserServiceImpl实现类

package cn.itcast.dubbo.service.impl;import java.util.ArrayList;
import java.util.List;import cn.itcast.dubbo.pojo.User;
import cn.itcast.dubbo.service.UserService;public class UserServiceImpl implements UserService {/*** 实现查询，这里做模拟实现，不做具体的数据库查询*/public List<User> queryAll() {List<User> list = new ArrayList<User>();for (int i = 0; i < 10; i++) {User user = new User();user.setAge(10 + i);user.setId(Long.valueOf(i + 1));user.setPassword("123456");user.setUsername("username_" + i);list.add(user);}return list;}}

8、在“src/main/resources”包中创建dubbo的配置文件“dubbo-applicationContext.xml”

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"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-4.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsdhttp://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="dubbo-b-server" /><!-- 这里使用的注册中心是zookeeper --><dubbo:registry address="zookeeper://127.0.0.1:2181" client="zkclient"/><!-- 用dubbo协议在20880端口暴露服务 --><dubbo:protocol name="dubbo" port="20880" /><!-- 将该接口暴露到dubbo中 --><dubbo:service interface="cn.itcast.dubbo.service.UserService" ref="userServiceImpl" /><!-- 将具体的实现类加入到Spring容器中 --><bean id="userServiceImpl" class="cn.itcast.dubbo.service.impl.UserServiceImpl" /><dubbo:monitor protocol="registry"></dubbo:monitor></beans>

9、使用spring与dubbo进行了无缝整合，要在web.xml中将配置文件引入

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"id="WebApp_ID" version="3.0"><display-name>dubbo-b</display-name><context-param><param-name>contextConfigLocation</param-name><param-value>classpath:dubbo-applicationContext.xml</param-value></context-param><!--Spring的ApplicationContext 载入 --><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list></web-app>

创建dubbo-a项目，作为服务消费方。

1、在Eclipse中点检新建项目，选择maven项目后，点击“next”：

2、项目存储位置，点击“next”：

3、因为建立的是“jar”项目，选择“maven-archetype-quickstart”,点击“next”：

4、填写Group ID（项目组织唯一的标识符）和Artifact ID（项目的唯一的标识符）点击“Finish”，完成项目创建。

5、在“pom.xml”导入依赖:

<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>cn.itcast.dubbo</groupId><artifactId>dubbo-a</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>dubbo-a</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.1.3.RELEASE</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.6.4</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>dubbo</artifactId><version>2.5.3</version><exclusions><exclusion><!-- 排除传递spring依赖 --><artifactId>spring</artifactId><groupId>org.springframework</groupId></exclusion></exclusions></dependency><dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.3.3</version></dependency><dependency><groupId>com.github.sgroschupf</groupId><artifactId>zkclient</artifactId><version>0.1</version></dependency><dependency><groupId>cn.itcast.dubbo</groupId><artifactId>dubbo-ab-api</artifactId><version>0.0.1-SNAPSHOT</version></dependency></dependencies>
</project>

6、在“src/main/resources”包中创建配置服务的消费者“dubbo-consumer.xml” 。

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"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-4.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsdhttp://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="dubbo-a-consumer" /><!-- 这里使用的注册中心是zookeeper --><dubbo:registry address="zookeeper://127.0.0.1:2181" client="zkclient"/><!-- 从注册中心中查找服务 --><dubbo:reference id="userService" interface="cn.itcast.dubbo.service.UserService"/></beans>

7、编写测试代码

public static void main( String[] args ){ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:*.xml");UserService userService = applicationContext.getBean(UserService.class);List<User> users = userService.queryAll();for (User user : users) {System.out.println(user);}}

运行结果截图：