Java语言的文件拷贝（输入输出流的相关知识已经是否带缓冲的比较）-优快云博客

本文比较了Java中三种文件拷贝方法：无缓冲、自定义带缓冲和使用BufferedInputStream和BufferedOutputStream。带缓冲的拷贝方式被证实效率最高。

/**
*不带缓冲的文件拷贝！效率最低
*/
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class CopyFile01
{
   public static void main(String[] args) throws Exception
   {
       if(args.length != 2)
       {
           System.out.println("用法：java CopyFile01 源文件目标文件");
           System.exit(0);
       }

FileInputStream in = new FileInputStream(args[0]);
FileOutputStream out = new FileOutputStream(args[1]);

int x = 0;

long start = System.currentTimeMillis();

       while((x = in.read()) != -1)
       {
           out.write(x);
       }

long end = System.currentTimeMillis();

System.out.println(args[0] + "拷贝完成！" + args[1] + "总共花费时间" + (end - start) + "毫秒！");

in.close();
out.close();

}
}

/**
*带缓冲的文件拷贝！效率最高
*/
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class CopyFile02
{
   public static void main(String[] args) throws Exception
   {
       if(args.length != 2)
       {
           System.out.println("用法：java CopyFile01 源文件目标文件");
           System.exit(0);
       }

FileInputStream in = new FileInputStream(args[0]);
FileOutputStream out = new FileOutputStream(args[1]);

int len = 0;
byte[] buf = new byte[1024]; //自定义一个1024字节的缓冲区

long start = System.currentTimeMillis();

       while((len = in.read(buf)) != -1)
       {
           out.write(buf, 0, len);
       }

long end = System.currentTimeMillis();

System.out.println(args[0] + "拷贝完成！" + args[1] + "总共花费时间" + (end - start) + "毫秒！");

in.close();
out.close();

}
}

/**
*自定义的带缓冲的文件拷贝！效率最高
*/
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;

public class CopyFile03
{
   public static void main(String[] args) throws Exception
   {
       if(args.length != 2)
       {
           System.out.println("用法：java CopyFile01 源文件目标文件");
           System.exit(0);
       }

BufferedInputStream bis = new BufferedInputStream(new FileInputStream(args[0]));
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(args[1]));

int x = 0;

long start = System.currentTimeMillis();

       while((x = bis.read()) != -1)
       {
           bos.write(x);
       }

long end = System.currentTimeMillis();

System.out.println(args[0] + "拷贝完成！" + args[1] + "总共花费时间" + (end - start) + "毫秒！");

bis.close();
bos.close();

}
}