Question

java 编写FileCopy类,要求将1个文件的内容同时复制成多个文件.使用命令行完成文件名的输入。

Answer 1

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;
import java.util.Date;
import java.util.Scanner;

public class FileCopy {

public static void main(String[] args) throws Exception {

File f1 = new File("D:\\test\\test.txt");
String path = "D:\\test\\";
System.out.print("请输入要复制的文件个数:");
Scanner sc = new Scanner(System.in);
int cnt = sc.nextInt();
for(int i = 0 ; i< cnt ; i++){
System.out.print("请输入第"+(i+1)+"个文件名:");
String newName = sc.next();
System.out.println("第"+(i+1)+"个文件的名字为:"+newName+".txt");
File f2 = new File(path+newName+".txt");
forTransfer(f1,f2);
}

}
/**
* @author Samsung
* @date 2017年4月20日15:20:25
* 实现文件内容的复制
*
* */
public static long forTransfer(File f1,File f2) throws Exception{
long time=new Date().getTime();
int length=2097152;
FileInputStream in=new FileInputStream(f1);
FileOutputStream out=new FileOutputStream(f2);
FileChannel inC=in.getChannel();
FileChannel outC=out.getChannel();
int i=0;
while(true){
if(inC.position()==inC.size()){
inC.close();
outC.close();
return new Date().getTime()-time;
}
if((inC.size()-inC.position())<20971520)
length=(int)(inC.size()-inC.position());
else
length=20971520;
inC.transferTo(inC.position(),length,outC);
inC.position(inC.position()+length);
i++;
}
}

}