Dubbo实践（一）入门示例

时间：2022-03-20 20:48:51

dubbo是一个分布式服务框架，致力于提供高性能和透明化的RPC远程服务调用方案，以及SOA服务治理方案。简单的说，dubbo就是个服务框架，如果没有分布式的需求，其实是不需要用的，只有在分布式的时候，才有dubbo这样的分布式服务框架的需求。

下面将介绍如何搭建一个简单的示例程序（用maven构建）。

众所周知，RPC调用涉及到消费者、提供者和接口，所以需要在maven工程warehouse-component-parent里面新建3个模块，分别是warehouse-component-dubbo-facade（接口）、warehouse-component-dubbo-provider（提供者）和warehouse-component-dubbo-consumer（消费者）。对应的pom文件如下。

warehouse-component-parent：

<?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>org.wu</groupId>
<artifactId>warehouse-component-parent</artifactId>
<version>0.0.1</version>
<packaging>pom</packaging>
<name>component warehouse parent</name>

<modules>
<module>warehouse-component-dubbo-facade</module>
<module>warehouse-component-dubbo-provider</module>
<module>warehouse-component-dubbo-consumer</module>
</modules>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<junit.version>4.12</junit.version>
<spring.version>4.3.8.RELEASE</spring.version>
<log4j.over.slf4j.version>1.7.25</log4j.over.slf4j.version>
<jcl.over.slf4j.version>1.7.25</jcl.over.slf4j.version>
<logback.version>1.2.3</logback.version>
<dubbo.version>2.5.3</dubbo.version>
<zkclient.version>0.1</zkclient.version>
</properties>

<dependencyManagement>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>

<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>

<!-- logback -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${jcl.over.slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>${log4j.over.slf4j.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback.version}</version>
</dependency>

<!-- dubbo -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>${dubbo.version}</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
<exclusion>
<groupId>org.springframework</groupId>
<artifactId>spring</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- zkclient -->
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>zkclient</artifactId>
<version>${zkclient.version}</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>

<dependency>
<groupId>org.wu</groupId>
<artifactId>warehouse-component-dubbo-facade</artifactId>
<version>${project.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
</project>

 warehouse-component-dubbo-provider：

<?xml version="1.0"?>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.wu</groupId>
<artifactId>warehouse-component-parent</artifactId>
<version>0.0.1</version>
</parent>
<artifactId>warehouse-component-dubbo-provider</artifactId>
<name>warehouse-component-dubbo-provider</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>
<scope>test</scope>
</dependency>
<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>

<!-- dubbo -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
</dependency>
<!-- zkclient -->
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>zkclient</artifactId>
</dependency>

<!-- logback -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</dependency>

<dependency>
<groupId>org.wu</groupId>
<artifactId>warehouse-component-dubbo-facade</artifactId>
</dependency>
</dependencies>
</project>

 warehouse-component-dubbo-consumer：

<?xml version="1.0"?>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.wu</groupId>
<artifactId>warehouse-component-parent</artifactId>
<version>0.0.1</version>
</parent>
<artifactId>warehouse-component-dubbo-consumer</artifactId>
<name>warehouse-component-dubbo-consumer</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>
<scope>test</scope>
</dependency>
<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
</dependency>
<!-- dubbo -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
</dependency>
<!-- zkclient -->
<dependency>
<groupId>com.github.sgroschupf</groupId>
<artifactId>zkclient</artifactId>
</dependency>

<!-- logback -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</dependency>

<dependency>
<groupId>org.wu</groupId>
<artifactId>warehouse-component-dubbo-facade</artifactId>
</dependency>
</dependencies>
</project>

工程使用的日志框架为logback，配置文件如下：

<?xml version="1.0" encoding="UTF-8" ?>

<configuration scan="true" scanPeriod="3 seconds">

<statusListener class="ch.qos.logback.core.status.OnConsoleStatusListener" />

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<layout class="ch.qos.logback.classic.PatternLayout">
<!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
<pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%-5level] [%logger:%L] %msg%n</pattern>
</layout>
</appender>

<appender name="ALL_LOG_FILE"
        class="ch.qos.logback.core.rolling.RollingFileAppender">
<File>warehouse_component.log</File>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<FileNamePattern>
                warehouse_component.%d{yyyy-MM-dd}.log
</FileNamePattern>
</rollingPolicy>

<layout class="ch.qos.logback.classic.PatternLayout">
<!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
<pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%-5level] [%logger:%L] %msg%n</pattern>
</layout>
</appender>

<appender name="ERROR_LOG_FILE"
        class="ch.qos.logback.core.rolling.RollingFileAppender">
<File>warehouse_component_error.log</File>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<FileNamePattern>
                warehouse_component_error.%d{yyyy-MM-dd}.log
</FileNamePattern>
</rollingPolicy>
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<level>ERROR</level>
</filter>

<layout class="ch.qos.logback.classic.PatternLayout">
<!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
<pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%-5level] [%logger:%L] %msg%n</pattern>
</layout>
</appender>

<root>
<level value="INFO" />
<appender-ref ref="STDOUT" />
<appender-ref ref="ALL_LOG_FILE" />
<appender-ref ref="ERROR_LOG_FILE" />
</root>

</configuration>

上述配置信息都设置好后，就可以进行dubbo程序的开发了。首先，定义dubbo接口，在warehouse-component-dubbo-facade模块中定义一个接口：

package org.warehouse.component.dubbo.facade;

public interface DemoFacade {
/**
     * dubbo接口
*/
    String sayHello(String name);
}

接口定义好后，dubbo服务提供者warehouse-component-dubbo-provider需要实现该接口，进行相关的业务逻辑处理。

package org.warehouse.component.dubbo.provider;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.stereotype.Service;
import org.warehouse.component.dubbo.facade.DemoFacade;

import com.alibaba.dubbo.rpc.RpcContext;

@Service("demoFacadeImpl")
public class DemoFacadeImpl implements DemoFacade {

    @Override
public String sayHello(String name) {
        System.out.println("[" + new SimpleDateFormat("HH:mm:ss").format(new Date()) + "] Hello " + name
+ ", request from consumer: " + RpcContext.getContext().getRemoteAddress());
return "Hello " + name + ", response form provider: " + RpcContext.getContext().getLocalAddress();
    }

}

并通过spring配置文件（dubbo-provider.xml）暴露该服务：

<?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:context="http://www.springframework.org/schema/context"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://code.alibabatech.com/schema/dubbo 
        http://code.alibabatech.com/schema/dubbo/dubbo.xsd">

<!-- 自动检测并装配bean -->
<context:component-scan base-package="org.warehouse.component.dubbo.provider" />

<!-- 提供方应用信息，用于计算依赖关系 -->
<dubbo:application name="provider-of-hello-world-app" />

<!-- 使用zookeeper注册中心暴露服务地址 -->
<dubbo:registry protocol="zookeeper" address="192.168.1.103:2181" />

<!-- 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.warehouse.component.dubbo.facade.DemoFacade" ref="demoFacadeImpl" />

</beans>

现在可以通过加载spring配置启动服务提供者了（运行以下代码）：

package org.warehouse.component.dubbo.provider;

import java.io.IOException;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {

public static void main(String[] args) throws IOException {
        @SuppressWarnings("resource")
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("dubbo-provider.xml");
        context.start();

        System.in.read();
    }

}

服务提供者启动之后，服务消费者通过spring配置（dubbo-consumer.xml）引用远程服务：

<?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:context="http://www.springframework.org/schema/context"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://code.alibabatech.com/schema/dubbo 
        http://code.alibabatech.com/schema/dubbo/dubbo.xsd">

<!-- 自动检测并装配bean -->
<context:component-scan base-package="org.warehouse.component.dubbo.consumer" />

<!-- 提供方应用信息，用于计算依赖关系 -->
<dubbo:application name="consumer-of-hello-world-app" />

<!-- 使用zookeeper注册中心暴露服务地址 -->
<dubbo:registry protocol="zookeeper" address="192.168.1.103:2181" />

<dubbo:reference id="demoFacade" interface="org.warehouse.component.dubbo.facade.DemoFacade" />

</beans>

加载Spring配置，并调用远程服务（这里是通过spring unit test的方式）：

package org.warehouse.component.dubbo.consumer;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.warehouse.component.dubbo.facade.DemoFacade;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:dubbo-consumer.xml"})
public class ConsumerTest {

    @Autowired
    ApplicationContext context;

    @Test
public void testDemoFacade() {
        DemoFacade facade = (DemoFacade) context.getBean("demoFacade");
        String hello = facade.sayHello("world");

        System.out.println(hello);
    }
}

服务的调用就像是方法本地调用一样简单，这其实是dubbo将底层通信封装好了，我们只需要关注业务逻辑实现。

在spring文件中配置dubbo服务时，eclipse会出现无法找到dubbo.xsd文件的问题。在本工程的解决办法是将dubbo-2.5.3.jar包中的dubbo.xsd文件（META-INF文件夹中）复制到文件系统中，然后

windows -> Preferrences -> XML -> XML Catalog

Add -> Catalog Entry -> File System 选择刚刚下载的文件路径

修改key值和配置文件的http://code.alibabatech.com/schema/dubbo/dubbo.xsd 相同

保存。。在xml文件右键validate ok解决了。

Dubbo实践（一）入门示例

最后还有一点需要说明：dubbo和zkclient需要排除对log4j的依赖后才可以使用logback来记录详细日志，具体排除方式已经在warehouse-component-parent的pom文件中展示。

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