package com.opslab.util.algorithmImpl;

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

/**

* 封装了集中常用的文件读的方法

*/

public class FileReadImpl {

/**

* 利用FileChannel直接实现文件的对拷,对于大文件速度特别明显

*

* @param source

* @param target

*/

public static void copyFileWithChannel(File source, File target) {

try (

FileInputStream inStream = new FileInputStream(source);

FileOutputStream outStream = new FileOutputStream(target);

FileChannel in = inStream.getChannel();

FileChannel out = outStream.getChannel();

) {

in.transferTo(0, in.size(), out);

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 使用FileChannel+Buffer实现文件的读取拷贝是一种极佳的方案

*

* @param source

* @param target

*/

public static void copyFileWithBuffer(File source, File target) {

try (

FileInputStream inStream = new FileInputStream(source);

FileOutputStream outStream = new FileOutputStream(target);

FileChannel in = inStream.getChannel();

FileChannel out = outStream.getChannel()

) {

ByteBuffer buffer = ByteBuffer.allocate(4096);

while (in.read(buffer) != -1) {

buffer.flip();

out.write(buffer);

buffer.clear();

}

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 利用Buffer实现文件的读取拷贝

*

* @param source

* @param target

*/

public static void customBufferBufferedStreamCopy(File source, File target) {

try (

InputStream fis = new BufferedInputStream(new FileInputStream(source));

OutputStream fos = new BufferedOutputStream(new FileOutputStream(target))

) {

byte[] buf = new byte[4096];

int i;

while ((i = fis.read(buf)) != -1) {

fos.write(buf, 0, i);

}

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 利用Buffer实现文件的读取拷贝

*

* @param source

* @param target

*/

public static void customBufferStreamCopy(File source, File target) {

try (

InputStream fis = new FileInputStream(source);

OutputStream fos = new FileOutputStream(target);

) {

byte[] buf = new byte[4096];

int i;

while ((i = fis.read(buf)) != -1) {

fos.write(buf, 0, i);

}

} catch (IOException e) {

e.printStackTrace();

}

}

}