android 文件MD5加密 对SD卡的操作

File filePath;
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED))// 判断是否插入SD卡
{    filePath = Environment.getExternalStorageDirectory(); // 获得sdcard的路径
StatFs stat = new StatFs(filePath.getPath()); // 创建StatFs对象，这个对象很重要SD卡的信息就靠它获取了
long blockSize = stat.getBlockSize(); // 获得block的大小
float totalBlocks = stat.getBlockCount(); // 获得总容量
int sizeInMb = (int) (blockSize * totalBlocks) / 1024 / 1024; // 转换成单位是兆的
long availableBlocks = stat.getAvailableBlocks(); // 获得可用容量
float percent = availableBlocks / totalBlocks; // 获得可用比例
percent = (int) (percent * 1000); // 舍去多余小数位数
FileByMD5 m_md5 = new FileByMD5();
String request = m_md5.md5sum(fDir + "/xxxx.xml");
}

public class FileByMD5 {  private char HEX_DIGITS[] = { '0', '1', '2', '3', '4', '5', '6', '7','8', '9',
'A', 'B', 'C', 'D', 'E', 'F' };  public String toHexString(byte[] b)
{
StringBuilder sb = new StringBuilder(b.length * 2);
for (int i = 0; i < b.length; i++)
{
sb.append(HEX_DIGITS[(b[i] & 0xf0) >>> 4]);
sb.append(HEX_DIGITS[b[i] & 0x0f]);
}
return sb.toString();
}  public String md5sum(String filename)
{
InputStream fis;
byte[] buffer = new byte[1024];
int numRead = 0;
MessageDigest md5;
try
{
fis = new FileInputStream(filename);
md5 = MessageDigest.getInstance("MD5");
while ((numRead = fis.read(buffer)) > 0)
{
md5.update(buffer, 0, numRead);
}
fis.close();
return toHexString(md5.digest());   }
catch (Exception e)
{
System.out.println("error");
return null;
}
}
} nbsp;