import java.io.IOException;import java.security.MessageDigest;import sun.misc.BASE64Encoder;import sun.misc.BASE64Decoder;public class MD5Util {    /**     * MD5加密     */     public static String md5Encryption(String str)  {          MessageDigest md5 = null;             try {              md5 = MessageDigest.getInstance("MD5");             } catch (Exception e) {              System.out.println(e.toString());              e.printStackTrace();              return "";             }             char[] charArray = str.toCharArray();             byte[] byteArray = new byte[charArray.length];                       for (int i = 0; i < charArray.length; i++)              byteArray[i] = (byte) charArray[i];                       byte[] md5Bytes = md5.digest(byteArray);                       StringBuffer hexValue = new StringBuffer();                       for (int i = 0; i < md5Bytes.length; i++) {              int val = ((int) md5Bytes[i]) & 0xff;              if (val < 16)               hexValue.append("0");              hexValue.append(Integer.toHexString(val));             }                       return hexValue.toString();     }          /**      * base64加密      */     public static String base64Encryption(String str)  {        if (str == null) return null;         String encodeStr = "";               try {            BASE64Encoder b64Encoder = new BASE64Encoder();            encodeStr = b64Encoder.encode(str.getBytes());        } catch (Exception e) {            e.printStackTrace();        }                       return encodeStr;    }     /**      * base64解密      */     public static String base64Dcrypt(String str)  {        if (str == null) return null;         String decoderStr = "";                try {            BASE64Decoder decoder = new BASE64Decoder();            byte[] b = decoder.decodeBuffer(str);            decoderStr = new String(b);        } catch (IOException e) {            e.printStackTrace();            return null;         }               return decoderStr;    }}