使用NIO的FileChannel和ByteBuffer高效读取文件

http://hi.baidu.com/boywell/blog/item/658d143f730a553770cf6ccd.html

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

public class ReadWriteCompare

{

public static void main(String[] args) throws IOException

{

FileInputStream fileInputStream = new FileInputStream("f:"+ File.separator +"IBM e-Mentor Program Kickoff Night 1105.pdf");

FileOutputStream fileOutputStream = new FileOutputStream("f:" + File.separator + "test.pdf");

FileChannel inChannel = fileInputStream.getChannel();

FileChannel outChannel= fileOutputStream.getChannel();

ByteBuffer byteBuffer = ByteBuffer.allocate(1024);

//Direct Buffer的效率会更高。

// ByteBuffer byteBuffer = ByteBuffer.allocateDirect(1024);

long start = System.currentTimeMillis();

while(true)

{

int eof = inChannel.read(byteBuffer);

if(eof == -1 ) break;

byteBuffer.flip();

outChannel.write(byteBuffer);

byteBuffer.clear();

}

System.out.println("spending : " + (System.currentTimeMillis()-start));

inChannel.close();

outChannel.close();

}

}