import java.security.*; import java.security.spec.*; 
class MD5_Test{ 
   public final static String MD5(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();        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 byte0 = md[i];          str[k++] = hexDigits[byte0 >>> 4 & 0xf];          str[k++] = hexDigits[byte0 & 0xf];          }          return new String(str);        }        catch (Exception e){          return null;        } }  public static void main(String[] args){  //MD5_Test aa = new MD5_Test(); 
 System.out.print(MD5_Test.MD5("XX"));  }
   
 
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