学步园

     通过"FileSystem.getFileBlockLocation（FileStatus
file，long start，long len）"可查找指定文件在HDFS集群上的位置，其中file为文件的完整路径，start和len来标识查找文件的路径。

以下是java代码的实现：

package com.njupt.hadoop;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;

public class FindFileOnHDFS {

public static void main(String[] args) throws Exception{
getHDFSNodes();
getFileLocal();
}

public static void getFileLocal() throws Exception {

Configuration conf = new Configuration();
FileSystem hdfs = FileSystem.get(conf);
Path fpath = new Path("/user/root/20120722/word.txt");

FileStatus fileStatus = hdfs.getFileStatus(fpath);
   BlockLocation[] blkLocations = hdfs.getFileBlockLocations(fileStatus, 0, fileStatus.getLen());

   int blockLen = blkLocations.length;
   
   for(int i = 0 ; i < blockLen ; ++i ){
    String[] hosts = blkLocations[i].getHosts();
    System.out.println("block_"+i + "_location:" + hosts[i]);
   }
}

public static void getHDFSNodes() throws Exception{
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
DistributedFileSystem hdfs = (DistributedFileSystem)fs;
DatanodeInfo[] dataNodeStats = hdfs.getDataNodeStats();

for( int i = 0 ; i < dataNodeStats.length ; ++i ){
System.out.println("DataNode_" + i + "_Node:" + dataNodeStats[i].getHostName());
}
}
}