采用Java语言如何实现高速文件复制？

今天review代码也看到了“大神”用老方法来实现文件拷贝

。今天归结一下使用Java语言怎样实现高速文件复制：

代码1——使用文件通道的方式：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

public class Test {
public static void main(String[] args){
long start = System.currentTimeMillis();
FileInputStream fileInputStream = null;
FileOutputStream fileOutputStream = null;
FileChannel inFileChannel = null;
FileChannel outFileChannel = null;
try {
fileInputStream = new FileInputStream(new File("C:\\from\\不是闹着玩的.flv"));
fileOutputStream = new FileOutputStream(new File("C:\\to\\不是闹着玩的.flv"));
inFileChannel = fileInputStream.getChannel();
outFileChannel = fileOutputStream.getChannel();
inFileChannel.transferTo(0, inFileChannel.size(), outFileChannel);//连接两个通道。从in通道读取数据写入out通道。

} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if(fileInputStream != null){
fileInputStream.close();
}
if(inFileChannel != null){
inFileChannel.close();
}
if(fileOutputStream != null){
fileOutputStream.close();
}
if(outFileChannel != null){
outFileChannel.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
long end = System.currentTimeMillis();
System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。

");
}
}

代码执行结果为：



代码2——使用缓冲输入输出流

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Test {
public static void main(String[] args){
long start = System.currentTimeMillis();
InputStream fileInputStream = null;
OutputStream fileOutputStream = null;
try {
fileInputStream = new BufferedInputStream( new FileInputStream(new File("C:\\from\\不是闹着玩的.flv")));
fileOutputStream = new BufferedOutputStream(new FileOutputStream(new File("C:\\to\\不是闹着玩的.flv")));
byte[] bufferArray = new byte[1024*1024];
int length;
while ((length = fileInputStream.read(bufferArray)) != -1) {
fileOutputStream.write(bufferArray, 0, length);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if(fileInputStream != null){
fileInputStream.close();
}
if(fileOutputStream != null){
fileOutputStream.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
long end = System.currentTimeMillis();
System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。");
}
}

代码执行结果为：



代码3——使用文件输入输出流的方式：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class Test {
public static void main(String[] args){
long start = System.currentTimeMillis();
FileInputStream fileInputStream = null;
FileOutputStream fileOutputStream = null;
try{
fileInputStream = new FileInputStream(new File("C:\\from\\不是闹着玩的.flv")); //读入原文件
fileOutputStream = new FileOutputStream("C:\\to\\不是闹着玩的.flv");
byte[] bufferArray = new byte[1024*1024];
int length;
while ((length = fileInputStream.read(bufferArray)) != -1) {
fileOutputStream.write(bufferArray, 0, length);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if(fileInputStream != null){
fileInputStream.close();
}
if(fileOutputStream != null){
fileOutputStream.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
long end = System.currentTimeMillis();
System.out.println("视频文件从“from”目录拷贝到“to”文件须要" + (end - start) + "毫秒。");
}
}

代码执行结果为：



代码1、代码2和代码3复制的是同样的文件，通过对比不难得出结论：：尝试使用文件时，文件拷贝输入和输出流可能是一个更好的办法。