【SSM分布式架构电商项目-33】Dubbo快速入门

快速入门

实现功能

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。
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安装zookeeper

解压得到如下:
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修改配置文件zoo.cfg: 该目录必须存在。
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启动zookeeper服务:
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搭建B系统

创建工程

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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>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>
配置log4j文件

log4j.properties:
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log4j.rootLogger=DEBUG,A1
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
创建User对象

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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;
    }

}
创建UserService(接口)提供查询服务

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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();

}
创建UserServiceImpl实现类

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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;
    }

}
编写dubbo配置文件

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具体配置:

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<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>
导入zookeeper依赖
<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>
编写Web.xml
<?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>
启动tomcat

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查看tomcat启动日志:

 dubbo version: 2.5.3, current host: 127.0.0.1
2018-05-17 14:49:20,819 [localhost-startStop-1] [com.alibaba.dubbo.config.AbstractConfig]-[INFO]  [DUBBO] Export dubbo service cn.itcast.dubbo.service.UserService to local registry, dubbo version: 2.5.3, current host: 127.0.0.1
2018-05-17 14:49:20,819 [localhost-startStop-1] [com.alibaba.dubbo.config.AbstractConfig]-[INFO]  [DUBBO] Export dubbo service cn.itcast.dubbo.service.UserService to url dubbo://172.20.10.6:20880/cn.itcast.dubbo.service.UserService?anyhost=true&application=dubbo-b-server&dubbo=2.5.3&interface=cn.itcast.dubbo.service.UserService&methods=queryAll&pid=13560&side=provider&timestamp=1526539760699, dubbo version: 2.5.3, current host: 127.0.0.1
2018-05-17 14:49:20,819 [localhost-startStop-1] [com.alibaba.dubbo.config.AbstractConfig]-[INFO]  [DUBBO] Register dubbo service cn.itcast.dubbo.service.UserService url dubbo://172.20.10.6:20880/cn.itcast.dubbo.service.UserService?anyhost=true&application=dubbo-b-server&dubbo=2.5.3&interface=cn.itcast.dubbo.service.UserService&methods=queryAll&pid=13560&side=provider&timestamp=1526539760699 to registry registry://127.0.0.1:2181/com.alibaba.dubbo.registry.RegistryService?application=dubbo-b-server&client=zkclient&dubbo=2.5.3&pid=13560&registry=zookeeper&timestamp=1526539760681, dubbo version: 2.5.3, current host: 127.0.0.1
2018-05-17 14:49:20,831 [localhost-startStop-1] [com.alibaba.dubbo.common.extension.ExtensionLoader]-[DEBUG]  [DUBBO] package com.alibaba.dubbo.rpc.cluster;

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。

搭建A系统

创建工程

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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>
    </dependencies>
</project>
配置log4j文件

log4j.properties:

log4j.rootLogger=DEBUG,A1
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
从b系统中拷贝User对象、UserService接口道a系统

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编写dubbo配置文件

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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>
编写UserService测试用例

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package cn.itcast.dubbo.service;

import static org.junit.Assert.*;

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;

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);
        }
    }

}
查看效果

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可以看到,已经查询到10条数据,那么,也就是说A系统通过B系统提供的服务获取到了数据。

解决代码重复问题

通过刚刚的示例我们可以发现,其中User对象和UserService在A系统和B系统中都使用,那么,我们是否应该讲该代码复用呢?

答案是肯定的。

在使用dubbo时,provider需要将提供服务所需要的java代码(bean、interface等)单独打包成jar提供给consumer使用。

创建dubbo-b-api

创建dubbo-b-api作为代码的抽取
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将dubbo-b中的pojo和service接口移动到dubbo-b-api中

删掉dubbo-a和dubbo-b的pojo和service
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在dubbo-b和dubbo-a的pom.xml文件中添加dubbo-b-api的依赖
        <dependency>
            <groupId>cn.itcast.dubbo</groupId>
            <artifactId>dubbo-b-api</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
测试

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测试,发现,和之前实现一样。

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转载自blog.csdn.net/cckevincyh/article/details/80350257