package cn.bigdata.hdfs.hadoopRpc.protocol;

//定义业务接口方法

public interface ClientNamenodeProtocol {

    // 协议版本号

    public static final long versionID = 1L;

    public String getMetaData(String path);

}

package cn.bigdata.hdfs.hadoopRpc.service;

import cn.bigdata.hdfs.hadoopRpc.protocol.ClientNamenodeProtocol;

public class MyNameNode implements ClientNamenodeProtocol{

    @Override

    public String getMetaData(String path) {

        // 模拟NameNode的业务方法，获取元数据

        return path+": 3 - {BLK_1,BLK_2} ...";

    }

}

package cn.bigdata.hdfs.hadoopRpc.service;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.ipc.RPC;

import org.apache.hadoop.ipc.RPC.Builder;

import org.apache.hadoop.ipc.RPC.Server;

import cn.bigdata.hdfs.hadoopRpc.protocol.ClientNamenodeProtocol;

//使用下面的代码可以把业务类发布为一个服务

public class PublishServiceUtil {

    public static void main(String[] args) throws IOException {

        Builder builder = new RPC.Builder(new Configuration());

        builder.setBindAddress("localhost")

        .setPort(8888)

        .setProtocol(ClientNamenodeProtocol.class)

        .setInstance(new MyNameNode());

        Server build = builder.build();

        build.start();

    }

}

package cn.bigdata.hdfs.hadoopRpc.client;

import java.net.InetSocketAddress;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.ipc.RPC;

import cn.bigdata.hdfs.hadoopRpc.protocol.ClientNamenodeProtocol;

public class MyHdfsClient {

    public static void main(String[] args) throws Exception {

        //获取代理对象

        ClientNamenodeProtocol nameNode = RPC.getProxy(ClientNamenodeProtocol.class,

                1L, // 这里指定的协议版本号要跟接口中的versionID的值保持一致

                new InetSocketAddress("localhost",8888),

                new Configuration());

        String metaData = nameNode.getMetaData("/angelababy");

        System.out.println(metaData);

    }

}