Rpc框架dubbo-server（v2.6.3）源码阅读（一）

　　额，dubbo的前世今生咱就不说了，有用的人都知道。（最新版本已更名 incubator-dubbo，预计版本3.0，不过咱们就先不掺和别人的开发过程了，以v2.6.3为蓝本）

　　首先，是工作需要，用到了dubbo用于微服务化各系统。所以，总体来说，是被动学习。
　　也就是先有了做，依葫芦画瓢，然后才来理解为什么！
　　当然，工作需要也不能全部不知道，自然是去官网看看有什么文档，看下其工作原理，可能出现的问题。以及在工作中解决问题用到的办法。总之，已经懂得七七八八了，但是，我们需要一个深度的学习。接下来就来走走看看！

　　抛个砖：dubbo提供者服务示例, 其结构是这样的！
　　dubbo://192.168.11.6:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=12720&side=provider&timestamp=1534902103892

拿来一个官网可以运行起来的实例，让代码跑起来：

// 提供者:
public class Provider {
    public static void main(String[] args) throws Exception {
        //Prevent to get IPV6 address,this way only work in debug mode
        //But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-provider.xml"});
        context.start();
        
        // 这个比较巧妙, 只需停留在当前点，不按下enter键，服务就会一直存在，等待消费者连接，而且无需真正提供一个监听服务
        System.in.read(); // press any key to exit
    }

}

// 消费者:
public class Consumer {
    public static void main(String[] args) {
        //Prevent to get IPV6 address,this way only work in debug mode
        //But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        DemoService demoService = (DemoService) context.getBean("demoService"); // get remote service proxy
        String hello = demoService.sayHello("world"); // call remote method, 调用远程服务和本地服务一样，这是其优势所在
        System.out.println(hello); // get result
        }
    }
}

// xml 配置，因为使用组播协议，所以demo拿来就可以运行
// 配置很简单，主要说明下这里使用组播地址的好处。组播是个很好的概念，可以使网络更快，也更方便开发，可以参考下: multicast，秒懂单播、广播或多播及其应用场景

provider:

<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="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>

    <!-- declare the service interface to be exported -->
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService"/>

</beans>

consumer:

<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="com.alibaba.dubbo.demo.DemoService"/>
</beans>

View Code