md5和base64加密解密

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;
    }
}