HDFS文件的tail

package com.xxx.hdfstail;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;


public class HDFSTailByLine_V4 {


String src;
Path path = null;
Configuration conf;
FileSystem srcFs;


public HDFSTailByLine_V4(String src) {
this.src = src;
path = new Path(src);
conf = new Configuration();
try {
srcFs = path.getFileSystem(conf);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}


private void tail() throws IOException {


if (srcFs.isDirectory(path)) {
throw new IOException("Source must be a file.");
}


long fileSize = srcFs.getFileStatus(path).getLen();


// 跳到最后一1024处开始tail
long offset = 0;


while (true) {


System.out.println(fileSize + "   " + offset);


FSDataInputStream in = srcFs.open(path);
in.seek(offset);


BufferedReader reader = new BufferedReader(
new InputStreamReader(in));
String tmp;
while ((tmp = reader.readLine()) != null) {
System.out.println(tmp);
System.out.println("===+++++===");
}


offset = in.getPos();
in.close();
reader.close();


System.out.println("=========");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
break;
}
System.out.println("sleep 3 s !");


}


}


public static void main(String[] args) throws Exception {


// String flumeAdd=args[1];
// String src=args[0];


String src = "hdfs://192.168.1.132:9000/user/hive/warehouse/log_asjh/ASJH_2013-12-05/ASJH_2013-12-05_00000";
// src=args[0];
HDFSTailByLine_V4 t = new HDFSTailByLine_V4(src);


t.tail();


}


}