1.用来判断文件大小的方法的类

package com.email.filesize;

import java.io.File;

import java.io.FileInputStream;

import java.text.DecimalFormat;

public class GetFileSize {

public GetFileSize() {

}

public long getFileSizes(File f) throws Exception {

long s = 0;

if (f.exists()) {

FileInputStream fis = null;

fis = new FileInputStream(f);

s = fis.available();

fis.close();

} else {

f.createNewFile();

System.out.println("文件夹不存在");

}

return s;

}

/**

* 递归

* */

public long getFileSize(File f) {

long size = 0;

File flist[] = f.listFiles();

for (int i = 0; i < flist.length; i++) {

if (flist[i].isDirectory()) {

size = size + getFileSize(flist[i]);

} else {

size = size + flist[i].length();

}

}

return size;

}

/**

* 转换文件大小

* */

public String FormentFileSize(long fileS) {

DecimalFormat df = new DecimalFormat("#.00");

String fileSizeString = "";

if (fileS < 1024) {

fileSizeString = df.format((double) fileS) + "B";

} else if (fileS < 1048576) {

fileSizeString = df.format((double) fileS / 1024) + "K";

} else if (fileS < 1073741824) {

fileSizeString = df.format((double) fileS / 1048576) + "M";

} else {

fileSizeString = df.format((double) fileS / 1073741824) + "G";

}

return fileSizeString;

}

///**

// * 递归求取目录文件个数

// * */

//public long getlist(File f) {

//long size = 0;

//File flist[] = f.listFiles();

//System.out.println("-------------" + flist.length);

//size = flist.length;

//for (int i = 0; i < flist.length; i++) {

//if (flist[i].isDirectory()) {

//size = size + getlist(flist[i]);

//size--;

//}

//}

//return size;

//}

}

2.判断文件大小，在主函数中写的语句

GetFileSize g = new GetFileSize();

String path = File.separator + "mnt" + File.separator + "sdcard" + File.separator + "1.txt";

File ff = new File(path);

try {

l = g.getFileSizes(ff);

} catch (Exception e) {

e.printStackTrace();

}

System.out.println(path + "文件的大小为：" + g.FormentFileSize(l));