hadoop[6]-rpc

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-common</artifactId>
    <version>2.4.1</version>
</dependency>

public interface NameNodeProtocal {
    //RPC通信双方一致的版本号
    public static final long versionID = 1L;
    //业务方法签名
    public String getMetaData(String path);
}

public class NameNodeProtocalImpl implements NameNodeProtocal {
    @Override
    public String getMetaData(String path) {
        return "metadata";
    }
}

import com.wange.service.NameNodeProtocal;
import com.wange.service.impl.NameNodeProtocalImpl;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RPC.*;
import java.io.IOException;

public class Application {
    public static void main(String[] args) throws Exception {
        //创建一个RPC服务builder
        Builder builder = new RPC.Builder(new Configuration());
        //将要发布的服务的信息设置到builder中
        builder.setBindAddress("hadoop-server-00").setPort(10000).setProtocol(NameNodeProtocal.class).setInstance(new NameNodeProtocalImpl());

        //用builder构建出一个socket服务
        Server server = builder.build();
        //将服务启动，就可以等待客户端请求
        server.start();
    }
}

import com.wange.service.NameNodeProtocal;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RPC.*;

import java.io.IOException;
import java.net.InetSocketAddress;

public class Application {
    public static void main(String[] args) throws IOException {
        System.setProperty("hadoop.home.dir", "E:/soft/hadoop-2.4.1");
        //首先用RPC框架获得要调用的远端服务的引用（动态代理对象）
        NameNodeProtocal namenodeImpl = RPC.getProxy(NameNodeProtocal.class, 1L, new InetSocketAddress("hadoop-server-00", 10000), new Configuration());
        //因为这个动态代理对象实现了业务类的接口，所以可以直接通过这个引用来调用业务类的实现方法(本质上，具体实现在远端，走的是socket通信请求)
        String metaData = namenodeImpl.getMetaData("/m1");

        System.out.println(metaData);
    }
}