组网扩展

<dubbo:protocol networker="xxx" />
<!-- 缺省值设置，当<dubbo:protocol>没有配置networker属性时，使用此配置 -->
<dubbo:provider networker="xxx" /> 

src
 |-main
    |-java
        |-com
            |-xxx
                |-XxxNetworker.java (实现Networker接口)
    |-resources
        |-META-INF
            |-dubbo
                |-org.apache.dubbo.remoting.p2p.Networker (纯文本文件，内容为：xxx=com.xxx.XxxNetworker)

package com.xxx;
 
import org.apache.dubbo.remoting.p2p.Networker;
 
public class XxxNetworker implements Networker {
    public Group lookup(URL url) {
        // ...
    }
}

xxx=com.xxx.XxxNetworker