/**
* MD5加密方法
*/
public static String MD5(String str) {
MessageDigest md5 = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
e.getMessage();
return "出错";
}
char[] charArray = str.toCharArray();
byte[] byteArray = new byte[charArray.length];
for (int i = 0; i < charArray.length; i++)
byteArray[i] = (byte) charArray[i];
byte[] md5Bytes = md5.digest(byteArray);
StringBuffer hexValue = new StringBuffer();
for (int i = 0; i < md5Bytes.length; i++) {
int val = ((int) md5Bytes[i]) & 0xff;
if (val < 16) {
hexValue.append("0");
}
hexValue.append(Integer.toHexString(val));
}
return hexValue.toString().toUpperCase();
}

以上返回的是小写的加密字符串

如果想得到大写的加密字符串只要在return sb.toString();这句话后面加上.toUpperCase()即可；

return sb.toString().toUpperCase();