Dubbo實踐（一）入門示例

時間  2019-11-11
標籤 dubbo 實踐 入門 示例 欄目 Dubbo 简体版
原文   原文鏈接

dubbo是一個分佈式服務框架，致力於提供高性能和透明化的RPC遠程服務調用方案，以及SOA服務治理方案。簡單的說，dubbo就是個服務框架，若是沒有分佈式的需求，實際上是不須要用的，只有在分佈式的時候，纔有dubbo這樣的分佈式服務框架的需求。java

下面將介紹如何搭建一個簡單的示例程序（用maven構建）。git

衆所周知，RPC調用涉及到消費者、提供者和接口，因此須要在maven工程warehouse-component-parent裏面新建3個模塊，分別是warehouse-component-dubbo-facade（接口）、warehouse-component-dubbo-provider（提供者）和warehouse-component-dubbo-consumer（消費者）。對應的pom文件以下。github

warehouse-component-parent：spring

<?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：apache

<?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：windows

<?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>

工程使用的日誌框架爲logback，配置文件以下：app

<?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">
        <!--格式化輸出：%d表示日期，%thread表示線程名，%-5level：級別從左顯示5個字符寬度%msg：日誌消息，%n是換行符-->
            <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">
            <!--格式化輸出：%d表示日期，%thread表示線程名，%-5level：級別從左顯示5個字符寬度%msg：日誌消息，%n是換行符-->
            <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">
            <!--格式化輸出：%d表示日期，%thread表示線程名，%-5level：級別從左顯示5個字符寬度%msg：日誌消息，%n是換行符-->
            <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>

上述配置信息都設置好後，就能夠進行dubbo程序的開發了。首先，定義dubbo接口，在warehouse-component-dubbo-facade模塊中定義一個接口：框架

package org.warehouse.component.dubbo.facade;

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

接口定義好後，dubbo服務提供者warehouse-component-dubbo-provider須要實現該接口，進行相關的業務邏輯處理。eclipse

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();
    }

}

並經過spring配置文件（dubbo-provider.xml）暴露該服務：maven

<?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">

    <!-- 自動檢測並裝配bean -->
    <context:component-scan base-package="org.warehouse.component.dubbo.provider" />

    <!-- 提供方應用信息，用於計算依賴關係 -->
    <dubbo:application name="provider-of-hello-world-app" />

    <!-- 使用zookeeper註冊中心暴露服務地址 -->
    <dubbo:registry protocol="zookeeper" address="192.168.1.103:2181" />
    
    <!-- 用dubbo協議在20880端口暴露服務 -->
    <dubbo:protocol name="dubbo" port="20880" />

    <!-- 聲明須要暴露的服務接口 -->
    <dubbo:service interface="org.warehouse.component.dubbo.facade.DemoFacade" ref="demoFacadeImpl" />

</beans>

如今能夠經過加載spring配置啓動服務提供者了（運行如下代碼）：

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();
    }

}

服務提供者啓動以後，服務消費者經過spring配置（dubbo-consumer.xml）引用遠程服務：

<?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">

    <!-- 自動檢測並裝配bean -->
    <context:component-scan base-package="org.warehouse.component.dubbo.consumer" />
    
    <!-- 提供方應用信息，用於計算依賴關係 -->
    <dubbo:application name="consumer-of-hello-world-app" />

    <!-- 使用zookeeper註冊中心暴露服務地址 -->
    <dubbo:registry protocol="zookeeper" address="192.168.1.103:2181" />
    
    <dubbo:reference id="demoFacade" interface="org.warehouse.component.dubbo.facade.DemoFacade" />

</beans>

加載Spring配置，並調用遠程服務（這裏是經過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);
    }
}

服務的調用就像是方法本地調用同樣簡單，這實際上是dubbo將底層通訊封裝好了，咱們只須要關注業務邏輯實現。

在spring文件中配置dubbo服務時，eclipse會出現沒法找到dubbo.xsd文件的問題。在本工程的解決辦法是將dubbo-2.5.3.jar包中的dubbo.xsd文件（META-INF文件夾中）複製到文件系統中，而後

windows -> Preferrences -> XML -> XML Catalog

Add -> Catalog Entry -> File System 選擇剛剛下載的文件路徑

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

保存。。在xml文件右鍵validate ok解決了。

最後還有一點須要說明：dubbo和zkclient須要排除對log4j的依賴後才能夠使用logback來記錄詳細日誌，具體排除方式已經在warehouse-component-parent的pom文件中展現。

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