Android：MD5 32位 16位小写加密

Message Digest Algorithm MD5（中文名为消息摘要算法第五版）为计算机安全领域广泛使用的一种散列函数，用以提供消息的完整性保护。MD5用的是哈希函数,在计算机网络中应用较多的不可逆加密算法有RSA公司发明的MD5算法和由美国国家技术标准研究所建议的安全散列算法SHA。

/*** MD5 32位加密方法一 小写* @param str* @return*/public final static String get32MD5(String s) {char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };try {byte[] strTemp = s.getBytes();//使用MD5创建MessageDigest对象MessageDigest mdTemp = MessageDigest.getInstance("MD5");mdTemp.update(strTemp);byte[] md = mdTemp.digest();int j = md.length;char str[] = new char[j * 2];int k = 0;for (int i = 0; i < j; i++) {byte b = md[i];//System.out.println((int)b);//将没个数(int)b进行双字节加密str[k++] = hexDigits[b >> 4 & 0xf];str[k++] = hexDigits[b & 0xf];}return new String(str);} catch (Exception e) {return null;}

 

/*** MD5 32位加密方法二 小写* @param str* @return*/public final static String get32MD5Str(String str) { MessageDigest messageDigest = null; try { messageDigest = MessageDigest.getInstance("MD5"); messageDigest.reset(); messageDigest.update(str.getBytes("UTF-8")); } catch (NoSuchAlgorithmException e) { System.out.println("NoSuchAlgorithmException caught!"); System.exit(-1); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } byte[] byteArray = messageDigest.digest(); StringBuffer md5StrBuff = new StringBuffer(); for (int i = 0; i < byteArray.length; i++) { if (Integer.toHexString(0xFF & byteArray[i]).length() == 1) md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i])); else md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i])); } return md5StrBuff.toString(); }

 

/*** Md5 32位 or 16位 加密* @param plainText * @return 32位加密*/public static String Md5(String plainText ) {StringBuffer buf = null;try {MessageDigest md = MessageDigest.getInstance("MD5"); md.update(plainText.getBytes());byte b[] = md.digest(); int i; buf = new StringBuffer(""); for (int offset = 0; offset < b.length; offset++) {i = b[offset];if(i<0) i+= 256;if(i<16)buf.append("0");buf.append(Integer.toHexString(i));}// Log.e("555","result: " + buf.toString());//32位的加密 //Log.e("555","result: " + buf.toString().substring(8,24));//16位的加密} catch (NoSuchAlgorithmException e) {// TODO Auto-generated catch blocke.printStackTrace();}return buf.toString(); }

 

附：java String 转化成 MD5 byte[]public static byte[] hexStringToByte(String hex) {int len = (hex.length() / 2); byte[] result = new byte[len];char[] achar = hex.toCharArray(); for (int i = 0; i < len; i++) {int pos = i * 2; result[i] = (byte) (toByte(achar[pos]) << 4 | toByte(achar[pos + 1])); } return result; } private static byte toByte(char c) { byte b = (byte) "0123456789abcdef".indexOf(c); return b; }