dubbo-Quick Start

Apache Dubbo：高性能、基于java的rpc开源框架
参考：http://dubbo.apache.org/

1、环境准备

IntelliJ idea
JDK: version 6 or higher
Maven: version 3 or higher

引用：

<dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>dubbo</artifactId>
      <version>2.5.3</version>
    </dependency>

2、定义服务接口

因为服务的提供者和消费者都依赖相同的接口，强烈建议将接口定义放在一个可以由提供者模块和消费者模块共享的独立模块中。

public interface DemoService {
    String sayHello(String name);
}

服务的提供者实现该接口：

public class Provider {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[] {"dubbo-demo-provider.xml"});
        context.start();
        // press any key to exit
        System.in.read();
    }
}

服务提供者的相关配置

<?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:dubbo="http://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <dubbo:application name="demo-provider"/>
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <dubbo:protocol name="dubbo" port="20880"/>
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService"/>
    <bean id="demoService" class="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>
</beans>

服务提供者启动

public class Provider {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[] {"dubbo-demo-provider.xml"});
        context.start();
        // press any key to exit
        System.in.read();
    }
}

消费者的相关配置

<?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:dubbo="http://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <dubbo:application name="demo-consumer"/>
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <dubbo:reference id="demoService" interface="com.alibaba.dubbo.demo.DemoService"/>
</beans>

运行服务消费者

public class Consumer {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
                new String[]{"dubbo-demo-consumer.xml"});
        context.start();
        // obtain proxy object for remote invocation
        DemoService demoService = (DemoService) context.getBean("demoService");
        // execute remote invocation
        String hello = demoService.sayHello("world");
        // show the result
        System.out.println(hello);
    }
}

可能遇到的问题：

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'demoService': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalStateException: Can't assign requested address
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport$1.run(FactoryBeanRegistrySupport.java:127)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:116)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:91)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:217)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:880)
    at com.go.dubbo.client.Consumer.main(Consumer.java:15)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: java.lang.IllegalStateException: Can't assign requested address
    at com.alibaba.dubbo.registry.multicast.MulticastRegistry.<init>(MulticastRegistry.java:116)
    at com.alibaba.dubbo.registry.multicast.MulticastRegistryFactory.createRegistry(MulticastRegistryFactory.java:30)
    at com.alibaba.dubbo.registry.support.AbstractRegistryFactory.getRegistry(AbstractRegistryFactory.java:94)
    at com.alibaba.dubbo.registry.RegistryFactory$Adpative.getRegistry(RegistryFactory$Adpative.java)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.refer(RegistryProtocol.java:240)
    at com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper.refer(ProtocolListenerWrapper.java:63)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper.refer(ProtocolFilterWrapper.java:60)
    at com.alibaba.dubbo.rpc.Protocol$Adpative.refer(Protocol$Adpative.java)
    at com.alibaba.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:392)
    at com.alibaba.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:300)
    at com.alibaba.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:138)
    at com.alibaba.dubbo.config.spring.ReferenceBean.getObject(ReferenceBean.java:65)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport$1.run(FactoryBeanRegistrySupport.java:121)
    ... 14 more
Caused by: java.net.SocketException: Can't assign requested address
    at java.net.PlainDatagramSocketImpl.join(Native Method)
    at java.net.AbstractPlainDatagramSocketImpl.join(AbstractPlainDatagramSocketImpl.java:179)
    at java.net.MulticastSocket.joinGroup(MulticastSocket.java:319)
    at com.alibaba.dubbo.registry.multicast.MulticastRegistry.<init>(MulticastRegistry.java:90)
    ... 26 more

需要配置VM参数：-Djava.net.preferIPv4Stack=true