使用Dubbo最常用的方式是與Spring Framework整合。下面內容，基於Spring Framework的XML配置，引導你開發一個Dubbo應用。如果不想依賴Spring，也可以試一下API配置。

首先建立名為dubbo-demo的根目錄：

mkdir dubbo-demo
cd dubbo-demo

接下來在根目錄下建立三個子目錄：

• dubbo-demo-api：普通的服務API。
• dubbo-demo-provider：服務供應者演示程式碼。
• dubbo-demo-consumer：服務消費者演示程式碼。

服務供應者

定義服務介面

DemoService.java:

package org.apache.dubbo.demo;

public interface DemoService {
    String sayHello(String name);

}

專案結構看起來如下：

.
├── dubbo-demo-api
│   ├── pom.xml
│   └── src
│       └── main
│           └── java
│               └── org
│                   └── apache
│                       └── dubbo
│                           └── demo
│                               └── DemoService.java
 

 實現服務介面：

DemoServiceImpl.java:

package org.apache.dubbo.demo.provider;
import org.apache.dubbo.demo.DemoService;

public class DemoServiceImpl implements DemoService {
    public String sayHello(String name) {
        return "Hello " + name;
    }
}

配置Spring暴露服務：

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- provider's application name, used for tracing dependency relationship -->
    <dubbo:application name="demo-provider"/>
    <!-- use multicast registry center to export service -->
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <!-- use dubbo protocol to export service on port 20880 -->
    <dubbo:protocol name="dubbo" port="20880"/>
    <!-- service implementation, as same as regular local bean -->
    <bean id="demoService" class="org.apache.dubbo.demo.provider.DemoServiceImpl"/>
    <!-- declare the service interface to be exported -->
    <dubbo:service interface="org.apache.dubbo.demo.DemoService" ref="demoService"/>
</beans>
 

示例使用multicast作為註冊服務中心，因為它簡單不需額外的安裝。如果更偏向使用zookeeper，請參考這裡。

配置日誌系統

Dubbo預設使用log4j作為日誌系統，它也支援slf4j，阿帕奇通用日誌，以及JUL日誌。

以下是簡單配置： log4j.properties

###set log levels###
log4j.rootLogger=info, stdout
###output to the console###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%d{dd/MM/yy hh:mm:ss:sss z}] %t %5p %c{2}: %m%n

引導服務提供者

Provider.java:

package org.apache.dubbo.demo.provider;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {

    public static void main(String[] args) throws Exception {
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-provider.xml"});
        context.start();
        System.out.println("Provider started.");
        System.in.read(); // press any key to exit
    }
}

專案目錄結構如下：

├── dubbo-demo-provider
│   ├── pom.xml
│   └── src
│       └── main
│           ├── java
│           │   └── org
│           │       └── apache
│           │           └── dubbo
│           │               └── demo
│           │                   └── provider
│           │                       ├── DemoServiceImpl.java
│           │                       └── Provider.java
│           └── resources
│               ├── META-INF
│               │   └── spring
│               │       └── dubbo-demo-provider.xml
│               └── log4j.properties

服務消費者

配置Spring引用遠端服務

consumer.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- consumer's application name, used for tracing dependency relationship (not a matching criterion),
    don't set it same as provider -->
    <dubbo:application name="demo-consumer"/>
    <!-- use multicast registry center to discover service -->
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <!-- generate proxy for the remote service, then demoService can be used in the same way as the
    local regular interface -->
    <dubbo:reference id="demoService" check="false" interface="org.apache.dubbo.demo.DemoService"/>
</beans>

引導消費者服務

Consumer.java:

import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.apache.dubbo.demo.DemoService;
 
public class Consumer {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        // Obtaining a remote service proxy
        DemoService demoService = (DemoService)context.getBean("demoService");
        // Executing remote methods
        String hello = demoService.sayHello("world");
        // Display the call result
        System.out.println(hello);
    }
}

配置日誌系統

與前述消費者服務配置相同。

最後目錄結構如下：

├── dubbo-demo-consumer
│   ├── pom.xml
│   └── src
│       └── main
│           ├── java
│           │   └── org
│           │       └── apache
│           │           └── dubbo
│           │               └── demo
│           │                   └── consumer
│           │                       └── Consumer.java
│           └── resources
│               ├── META-INF
│               │   └── spring
│               │       └── dubbo-demo-consumer.xml
│               └── log4j.properties

啟動演示

啟動服務供應者

執行org.apache.dubbo.demo.provider.Provider類啟動供應者。

啟動服務消費者

執行org.apache.dubbo.demo.provider.Consumer類啟動消費者，應該可以看到如下輸出：

Hello world

完整示例

Github倉庫完整示例程式碼：