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;
        }

        @Override
        public 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.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/tx http://www.springframework.org/schema/tx/spring-tx-4.0.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="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.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/tx http://www.springframework.org/schema/tx/spring-tx-4.0.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="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：