JAVA读取大文件最后一行

package com.dfsoft.eagle.domain.dis.protocol101;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;

public class DDD {

/**
* Created by wuhaowei([e-mail])
* @DATE:2011-3-29 下午04:34:47
*
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
File file = new File("E:/a.txt"); // 100M
long start = System.currentTimeMillis();
String lastLine = readLastLine(file, "GBK");
long delt = System.currentTimeMillis() - start;
System.out.println(lastLine);
System.out.println("读取时间(毫秒):" + delt);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

/*
* file = new File("E:/b.txt");// 仅一行文字 start =
* System.currentTimeMillis(); lastLine = readLastLine(file, "gbk");
* delt = System.currentTimeMillis() - start;
* System.out.println(lastLine); System.out.println("读取时间(毫秒):" + delt);
*/
}

public static String readLastLine(File file, String charset)
throws IOException {
if (!file.exists() || file.isDirectory() || !file.canRead()) {
return null;
}
RandomAccessFile raf = null;
try {
raf = new RandomAccessFile(file, "r");
long len = raf.length();
if (len == 0L) {
return "";
} else {
long pos = len - 1;
while (pos > 0) {
pos--;
raf.seek(pos);
if (raf.readByte() == '\n') {
break;
}
}
if (pos == 0) {
raf.seek(0);
}
byte[] bytes = new byte[(int) (len - pos)];
raf.read(bytes);
if (charset == null) {
return new String(bytes);
} else {
return new String(bytes, charset);
}
}
} catch (FileNotFoundException e) {
} finally {
if (raf != null) {
try {
raf.close();
} catch (Exception e2) {
}
}
}
return null;
}

}