Hadoop里的rpc框架可以單獨拿出來使用。jar包全在hadoop-common工程里。
導入hadoop-common工程里（hadoop-2.7.3為例）：
hadoop-common-2.7.3.jar
\hadoop-2.7.3\share\hadoop\common\lib下的全部jar包
實例
rpc.client ? 客戶端
rpc.protocol ?（數據傳遞的）協議層
rpc.service 服務端
package rpc.client;import java.net.InetSocketAddress;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.ipc.RPC;import rpc.protocol.IClientNamenodeProtocol;public class MyHdfsClient {public static void main(String[] args) throws Exception {IClientNamenodeProtocol proxy = RPC.getProxy(IClientNamenodeProtocol.class, 1L, new InetSocketAddress("localhost", 8888), new Configuration());String metaData = proxy.getMetaData("/hellohellohelloxxxxxxx.xxx");System.out.println("獲取到結果："+metaData);}}
package rpc.protocol;/*** 通信接口* * @author zengmiaogen**/
public interface IClientNamenodeProtocol {//hadoop-rpc框架要求有的變量versionID，沒有報錯public final long versionID=1L;public String getMetaData(String path);
}
package rpc.service;import rpc.protocol.IClientNamenodeProtocol;public class MyNameNode implements IClientNamenodeProtocol{/*** 模擬NameNode的業務方法之一，查詢元數據* @param path* @return*/@Overridepublic String getMetaData(String path){//假的，模擬的System.out.println("傳入的路徑："+path);return path+": 副本數量3-{BLK-1,BLK-2}-NameNode.......";}}
package rpc.service;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 rpc.protocol.IClientNamenodeProtocol;/*** 啟動服務器* @author zengmiaogen**/
public class PublishServiceUtil {public static void main(String[] args) throws Exception {Builder builder = new RPC.Builder(new Configuration());builder.setBindAddress("localhost").setPort(8888).setProtocol(IClientNamenodeProtocol.class).setInstance(new MyNameNode());Server server = builder.build();server.start();}}
步驟：
1、運行PublishServiceUtil.java 啟動服務端
2、運行MyHdfsClient.java 訪問服務端
結果：
客戶端
log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
獲取到結果：/hellohellohelloxxxxxxx.xxx: 副本數量3-{BLK-1,BLK-2}-NameNode.......
服務端
log4j:WARN No appenders could be found for logger (org.apache.hadoop.ipc.Server).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
傳入的路徑：/hellohellohelloxxxxxxx.xxx
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