java中利用RandomAccessFile读取超大文件

package com.javaer.examples.file;

import java.io.IOException;
import java.io.RandomAccessFile;

public class ReadBigFile {
public static void readBigFile() throws IOException{
String fileName = "/Users/mc2/Desktop/youku.txt";
RandomAccessFile randomFile = null;
randomFile = new RandomAccessFile(fileName, "r");
long fileLength = randomFile.length();
System.out.println("文件大小:" + fileLength);
int start = 46000;
randomFile.seek(start);
byte[] bytes = new byte[91];
int byteread = 0;
// 一次读10个字节，如果文件内容不足10个字节，则读剩下的字节。
// 将一次读取的字节数赋给byteread
while ((byteread = randomFile.read(bytes)) != -1) {
// System.out.write(bytes, 0, byteread);
}
System.out.println(bytes.length);
System.out.println(new String(bytes,"UTF-8"));
if (randomFile != null) {
randomFile.close();
}

}
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
ReadBigFile.readBigFile();
}

}

byte[] bytes = new byte[91];
int byteread = 0;
// 一次读10个字节，如果文件内容不足10个字节，则读剩下的字节。
// 将一次读取的字节数赋给byteread
while ((byteread = randomFile.read(bytes)) != -1) {
// System.out.write(bytes, 0, byteread);
}
System.out.println(bytes.length);byte[] bytes ;
int byteread = 0;

ByteArrayOutputStream byteout = new ByteArrayOutputStream();
byte tmp[] = new byte[1024];
byte context[];
int i = 0;
int has=0;
while ((i = randomFile.read(tmp)) != -1) {
byteout.write(tmp, 0, i);
has +=i;
if(has > 10240)
break;
}
bytes = byteout.toByteArray();