Hadoop-RPC应用demo

Hadoop里的rpc框架可以单独拿出来使用。jar包全在hadoop-common工程里。

导入hadoop-common工程里（hadoop-2.7.3为例）：

hadoop-common-2.7.3.jar

\hadoop-2.7.3\share\hadoop\common\lib下的全部jar包

实例



rpc.client   客户端

rpc.protocol  （数据传递的）协议层

rpc.service 服务端

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("获取到结果："+metaData);
}

}

package rpc.protocol;

/**
* 通信接口
*
* @author zengmiaogen
*
*/
public interface IClientNamenodeProtocol {
//hadoop-rpc框架要求有的变量versionID，没有报错
public final long versionID=1L;

public String getMetaData(String path);
}

package rpc.service;

import rpc.protocol.IClientNamenodeProtocol;

public class MyNameNode implements IClientNamenodeProtocol{

/**
* 模拟NameNode的业务方法之一，查询元数据
* @param path
* @return
*/
@Override
public String getMetaData(String path){
//假的，模拟的
System.out.println("传入的路径："+path);
return path+": 副本数量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;

/**
* 启动服务器
* @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();
}

}

步骤：

1、运行PublishServiceUtil.java 启动服务端

2、运行MyHdfsClient.java 访问服务端

结果：

客户端

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.
获取到结果：/hellohellohelloxxxxxxx.xxx: 副本数量3-{BLK-1,BLK-2}-NameNode.......

服务端

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.
传入的路径：/hellohellohelloxxxxxxx.xxx

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