java--获取文件夹大小

package com;
import java.util.ArrayList;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintStream;
import java.io.RandomAccessFile;
import java.io.SequenceInputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Scanner;
import java.util.Vector;

import com.bean.Student;

public class DIGUI {

public static void main(String[] args) throws IOException, ClassNotFoundException {
	//extracted_8();
	File dir =getDir();
	System.out.println(getFileLength(dir));
}
public static long getFileLength(File dir) {
	long len = 0;
	File[] subFile =dir.listFiles();
	for (File file : subFile) {
		if(file.isFile()) {
			len = len+file.length();
		}else {
			len=len+getFileLength(file);
		}
	}
	return len;
}
public static File getDir() {
	Scanner sc =new Scanner(System.in); 
	while(true) {
		String line = sc.nextLine();
		File dir =new File(line);
		if(!dir.exists()) {
			System.out.println("路基不存在");
		}else if(dir.isFile()) {
			System.out.println("是文件");
		}else {
			return dir;
		}
	}
}