import java.security.MessageDigest;  import java.security.NoSuchAlgorithmException;    public class Test {     public static void main(String[] args) {    Test test = new Test();    System.out.println(test.encryption("12345678"));   }     /**    *     * @param plainText    *            明文    * @return 32位密文    */   public String encryption(String plainText) {    String re_md5 = new String();    try {     MessageDigest md = MessageDigest.getInstance("MD5");     md.update(plainText.getBytes());     byte b[] = md.digest();       int i;       StringBuffer 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));     }       re_md5 = buf.toString();      } catch (NoSuchAlgorithmException e) {     e.printStackTrace();    }    return re_md5;   }  }