首先服务端和客户端都需要导入hadoop包内的/common下的三个jar，以及/common/lib所有依赖包。

然后服务端和客户端所在包(就是项目内路径)必须一致,否则会出现如下错误

Exception in thread "main" java.lang.reflect.UndeclaredThrowableException
	at com.sun.proxy.Proxy4.login(Unknown Source)
	at rpc2.get_server.main(get_server.java:12)
Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.ipc.RpcServerException): Unknown protocol: rpc2.test_face
	at org.apache.hadoop.ipc.WritableRpcEngineServerWritableRpcInvoker.call(WritableRpcEngine.java:493)
	at org.apache.hadoop.ipc.RPCServer.call(RPC.java:969)
	at org.apache.hadoop.ipc.ServerHandler1.run(Server.java:2049)
	at org.apache.hadoop.ipc.ServerHandler1.run(Server.java:2045)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
	at org.apache.hadoop.ipc.ServerHandler.run(Server.java:2043)

	at org.apache.hadoop.ipc.Client.call(Client.java:1476)
	at org.apache.hadoop.ipc.Client.call(Client.java:1407)
	at org.apache.hadoop.ipc.WritableRpcEngineInvoker.invoke(WritableRpcEngine.java:242)
	... 2 more

下面给出服务端代码,test是实现类，test_face是接口

start启动类:

package rpc;
import java.io.IOException;

import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RPC.Server;

public class start {
	public static void main(String [] args) throws HadoopIllegalArgumentException, IOException{
		RPC.Builder builder =new RPC.Builder(new Configuration());
		builder.setBindAddress("192.168.1.116").setPort(1234).setProtocol(test_face.class).setInstance(new test());
		Server server = builder.build();
		server.start();
	}
}

test_face接口:

package rpc;

public interface test_face {
	public static final long versionID=1L;
	public String login(String name);
}

test实现类:

package rpc;

public class test implements test_face{

	public String login(String name)
	{
		return name +" login!";
	}
}

【客户端代码】

把服务端test_face复制过来，然后实现类:

package rpc;

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

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;

public class get_server {
	public static void main(String[] args) throws Exception {
		test_face proxy = RPC.getProxy(test_face.class, test_face.versionID, new InetSocketAddress("192.168.1.116", 1234), new Configuration());
		String result = proxy.login("dawxy");//调用服务端的test类
		System.out.println(result);
	}
}