java学习笔记7对于将从控制台进行输入改为文件

import java.io.File;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.FileInputStream;
import java.util.Scanner;
public class Main
{
public static void main(String [] agrs)
throws Exception
{
System.setIn(new FileInputStream(new File("D:"+File.separator+"imput.txt")));
Scanner cin=new Scanner(System.in);
int B=cin.nextInt();
System.out.println(B);
}
}