android获取指定文件大小

/**
	 * 获取指定文件大小
	 * @param f
	 * @return
	 * @throws Exception 　　
	 */
	public static long getFileSize(File file) throws Exception {
		long size = 0;
		if (file.exists()) {
			FileInputStream fis = null;
			fis = new FileInputStream(file);
			size = fis.available();
		} else {
			file.createNewFile();
			Log.e("获取文件大小", "文件不存在!");
		}
		return size;
	}

/**
	 * 获取指定文件夹
	 * @param f
	 * @return
	 * @throws Exception
	 *
	 */
	public static long getFileSizes(File f) throws Exception {
		long size = 0;
		File flist[] = f.listFiles();
		for (int i = 0; i < flist.length; i++) {
			if (flist[i].isDirectory()) {
				size = size + getFileSizes(flist[i]);
			} else {
				size = size + getFileSize(flist[i]);
			}
		}
		return size;
	}

/**
	 * 转换文件大小
	 * @param fileS
	 * @return
	 *
	 */
	public static String FormetFileSize(long fileS) {
		DecimalFormat df = new DecimalFormat("#.00");
		String fileSizeString = "";
		String wrongSize = "0B";
		if (fileS == 0) {
			return wrongSize;
		}
		if (fileS < 1024) {
			fileSizeString = df.format((double) fileS) + "B";
		} else if (fileS < 1048576) {
			fileSizeString = df.format((double) fileS / 1024) + "KB";
		} else if (fileS < 1073741824) {
			fileSizeString = df.format((double) fileS / 1048576) + "MB";
		} else {
			fileSizeString = df.format((double) fileS / 1073741824) + "GB";
		}
		return fileSizeString;
	}