根据之前几篇文章搜集的资料，写了这么个简单的实例，仅供参考。
package org.apache.hadoop.examples;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FSDataOutputStream;
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 WordCount {
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
conf.set("mapred.job.tracker", "master:9001");
conf.set("fs.default.name", "hdfs://master:9000");
System.out.println("fs.default.name:" + conf.get("fs.default.name"));
System.out.println("mapred.job.tracker:" + conf.get("mapred.job.tracker"));
//从本地拷贝文件到hdfs
FileSystem fs = FileSystem.get(conf);
Path src = new Path("D:/hello.txt");
Path dst = new Path("hdfs://master:9000/abc");
fs.copyFromLocalFile(src, dst);
//创建文件
byte[] buff="hello hadoop world!\n".getBytes();
Path dfs = new Path("/test");
FSDataOutputStream outputStream = fs.create(dfs);
outputStream.write(buff,0,buff.length);
//创建目录
Path dfs1 = new Path("/TestDir");
fs.mkdirs(dfs1);
//重命名
Path frpaht = new Path("/test"); //旧的文件名
Path topath = new Path("/test1"); //新的文件名
boolean isRename=fs.rename(frpaht, topath);
String result = isRename ? "成功" : "失败";
System.out.println("文件重命名结果为：" + result);
//删除HDFS上的文件或目录
Path delef = new Path("/TestDir");
fs.delete(delef, true);//true代表递归删除
//查看某个HDFS文件是否存在
Path findf = new Path("/test1");
boolean isExists = fs.exists(findf);
System.out.println("Exist?"+isExists);
//查看HDFS文件的最后修改时间
Path fpath = new Path("/test1");
FileStatus fileStatus = fs.getFileStatus(fpath);
long modiTime = fileStatus.getModificationTime();
System.out.println("test1的修改时间是"+modiTime);
//读取HDFS某个目录下的所有文件
Path fpath1 = new Path("/");
//fs.getPath(fpath1);
FileStatus[] status = fs.listStatus(fpath1);
for (FileStatus file : status) {
System.out.println(file.getPath().getName());
}
//查找某个文件在HDFS集群的位置
Path fpath2 = new Path("/qj");
FileStatus filestatus = fs.getFileStatus(fpath2);
BlockLocation[] blkLocations = fs.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[0]);
}
//获取HDFS集群上所有节点名称信息
DistributedFileSystem hdfs = (DistributedFileSystem)fs;
DatanodeInfo[] dataNodeStats = hdfs.getDataNodeStats();
for(int i=0;i<dataNodeStats.length;i++){
System.out.println("DataNode_"+i+"_Name:"+dataNodeStats[i].getHostName());
}
}
}
本文参考了以下两篇：