本篇使用java自带的MessageDigest实现对文本的md5加密算法，具体代码如下：

 /**     *@Description: 将字符串转化为MD5   */   package cn.yicha.novel.util;      import java.security.MessageDigest;  import java.security.NoSuchAlgorithmException;      public class ParseMD5 {     /**    * @param str    * @return    * @Date: 2013-9-6      * @Author: lulei      * @Description:  32位小写MD5    */   public static String parseStrToMd5L32(String str){    String reStr = null;    try {     MessageDigest md5 = MessageDigest.getInstance("MD5");     byte[] bytes = md5.digest(str.getBytes());     StringBuffer stringBuffer = new StringBuffer();     for (byte b : bytes){      int bt = b&0xff;      if (bt < 16){       stringBuffer.append(0);      }       stringBuffer.append(Integer.toHexString(bt));     }     reStr = stringBuffer.toString();    } catch (NoSuchAlgorithmException e) {     e.printStackTrace();    }    return reStr;   }      /**    * @param str    * @return    * @Date: 2013-9-6      * @Author: lulei      * @Description: 32位大写MD5    */   public static String parseStrToMd5U32(String str){    String reStr = parseStrToMd5L32(str);    if (reStr != null){     reStr = reStr.toUpperCase();    }    return reStr;   }      /**    * @param str    * @return    * @Date: 2013-9-6      * @Author: lulei      * @Description: 16位小写MD5    */   public static String parseStrToMd5U16(String str){    String reStr = parseStrToMd5L32(str);    if (reStr != null){     reStr = reStr.toUpperCase().substring(8, 24);    }    return reStr;   }      /**    * @param str    * @return    * @Date: 2013-9-6      * @Author: lulei      * @Description: 16位大写MD5    */   public static String parseStrToMd5L16(String str){    String reStr = parseStrToMd5L32(str);    if (reStr != null){     reStr = reStr.substring(8, 24);    }    return reStr;   }  }