Dubbo服务的搭建

　　dubbo框架主要作用是基于RPC的远程调用服务管理，但是注册中心是用的zookeeper，搭建dubbo，首先要安装zookeeper，配置zookeeper。。。

实现功能如图所示：（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）

一、安装zookeeper

1、解压下载的安装包

2、修改配置文件zoo.cfg（解压出来不是这个名字，是zoo_sample.cfg，改了一下名字）：该目录必须存在。

3、启动zookeeper服务：

二、搭建B系统

1、创建工程（maven工程）

2、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-b</artifactId>
     <version>1.0.0-SNAPSHOT</version>
     <packaging>war</packaging>

     <dependencies>
         <!-- dubbo采用spring配置方式，所以需要导入spring容器依赖 -->
         <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>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>8181</port>
                     <path>/</path>
                 </configuration>
             </plugin>
         </plugins>
     </build>
 </project>

3、配置log4j文件

 log4j.rootLogger=DEBUG,A1
 log4j.logger.com.taotao = DEBUG
 log4j.logger.org.mybatis = DEBUG

 log4j.appender.A1=org.apache.log4j.ConsoleAppender
 log4j.appender.A1.layout=org.apache.log4j.PatternLayout
 log4j.appender.A1.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c]-[%p] %m%n

4、创建User对象

package cn.itcast.dubbo.pojo;

//使用dubbo要求传输的对象必须实现序列化接口
public class User implements java.io.Serializable {

    private static final long serialVersionUID = -2668999087589887337L;

    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;
    }

}

5、创建UserService（接口）提供查询服务

 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();

 }

6、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;
     }

 }

7、编写dubbo配置文件

具体配置：（dubbo-server.xml的配置，注意这个自己在eclipse中导入一下dubbo的xsd约束文件，不然会报错的）

 <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"/>

 </beans>

8、编写web.xml 文件，主要是配置spring的容器，项目启动的时候启动spring的容器

 <?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_2_5.xsd"
     id="WebApp_ID" version="2.5">
     <display-name>dubbo-b</display-name>

     <context-param>
         <param-name>contextConfigLocation</param-name>
         <param-value>classpath:dubbo/dubbo-*.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>

9、启动Tomcat（Maven Build的方式启动Tomcat）

查看Tomcat日志：发现userservice的服务已经发布成功了。

 2019-05-19 21:59:13,588 [localhost-startStop-1] [com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry]-[INFO]  [DUBBO] Load registry store file C:\Users\ssc\.dubbo\dubbo-registry-127.0.0.1.cache, data: {cn.itcast.dubbo.service.UserService=empty://169.254.103.222:20880/cn.itcast.dubbo.service.UserService?anyhost=true&application=dubbo-b-server&category=configurators&check=false&dubbo=2.5.3&interface=cn.itcast.dubbo.service.UserService&methods=queryAll&pid=3936&side=provider&timestamp=1558177989176}, dubbo version: 2.5.3, current host: 127.0.0.1
 2019-05-19 21:59:13,606 [localhost-startStop-1] [org.I0Itec.zkclient.ZkConnection]-[DEBUG] Creating new ZookKeeper instance to connect to 127.0.0.1:2181.
 2019-05-19 21:59:13,608 [ZkClient-EventThread-19-127.0.0.1:2181] [org.I0Itec.zkclient.ZkEventThread]-[INFO] Starting ZkClient event thread.

可以看到，已经将UserService服务注册到zookeeper注册中心，协议采用的是dubbo

三、搭建A系统

1、创建工程

2、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>

     <dependencies>
         <!-- dubbo采用spring配置方式，所以需要导入spring容器依赖 -->
         <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>

         <!-- 单元测试 -->
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.10</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
 </project>

3、配置log4j文件

 log4j.rootLogger=DEBUG,A1
 log4j.logger.com.taotao = DEBUG
 log4j.logger.org.mybatis = DEBUG

 log4j.appender.A1=org.apache.log4j.ConsoleAppender
 log4j.appender.A1.layout=org.apache.log4j.PatternLayout
 log4j.appender.A1.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c]-[%p] %m%n

4、从b系统中拷贝User对象、UserService接口到a系统

5、编写dubbo配置文件

配置文件如下：

 <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:referenceid="userService" interface="cn.itcast.dubbo.service.UserService"/>

 </beans>

6、编写UserService测试用例

 package cn.itcast.dubbo.service;

 import java.net.InetAddress;
 import java.util.List;

 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 import cn.itcast.dubbo.pojo.User;

 import com.alibaba.dubbo.common.utils.NetUtils;

 public class UserServiceTest {

     private UserService userService;

     @Before
     public void setUp() throws Exception {
         ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:dubbo/*.xml");
         this.userService = applicationContext.getBean(UserService.class);
     }

     @Test
     public void testQueryAll() {
         List<User> users = this.userService.queryAll();
         for (User user : users) {
             System.out.println(user);
         }
     }

     public static void main(String[] args) {
         InetAddress localAddress = NetUtils.getLocalAddress();
         System.out.println(localAddress.getHostAddress());

     }
 }

四、解决代码重复的问题

1、创建dubbo-b-api

2、将dubbo-b中的pojo和service接口移动到dubbo-b-api中

3、在dubbo-b的pom.xml文件中添加dubbo-b-api的依赖

4、在dubbo-a的pom.xml文件中添加dubbo-b-api的依赖，并且将pojo与service接口删除

5、分别删除dubbo-a和dubbo-b中的重复代码

注意：启动时，不要忘记吧dubbo-b-api项目maven install安装到中央仓库