java实现MD5加密的方法小结

private String getMD5Str(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();}

import java.security.MessageDigest;public class Test_MD5{  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();      //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;    }  }  //测试  public static void main(String[] args) {    System.out.println("caidao的MD5加密后：/n"+Test_MD5.MD5("caidao"));    System.out.println("http://www.baidu.com/的MD5加密后：/n"+Test_MD5.MD5("http://www.baidu.com/"));  }}