标准DES加密解密类

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
 * 标准DES加密解密类
 */
public class Des3Utility {
   private static final String ALGORITHM = "DESede";
   private static final String ENCODING = "UTF-8";
   private static final String HEX_SOURCE = "0123456789ABCDEF";

   /**
    * 字节码转十六进制字符串
    * @param sources
    *        字节码
    * @return
    */
   private static String byteToHex(byte[] sources) {
      if(sources == null || sources.length == 0){
         return null;
      }
      StringBuffer result = new StringBuffer();
      for(byte source : sources){
         String tmp = (Integer.toHexString(source & 0XFF));
         if(tmp.length() == 1){
            result.append("0" + tmp);
         }else{
            result.append(tmp);
         }
      }
      return result.toString().toUpperCase();
   }

   /**
    * 十六进制字符串转字节码
    * @param source
    *        十六进制字符串
    * @return
    * @throws Exception
    */
   public static byte[] hexToByte(String source) throws Exception {
      if(source.length() % 2 != 0){
         throw new IllegalArgumentException("给定的十六进制字符串的长度不是偶数");
      }
      char[] sourceChars = source.toUpperCase().toCharArray();
      int length = sourceChars.length/2;
      byte buffer[] = new byte[length];
      for(int index = 0;index < length;index++) {
         buffer[index] = (byte) (HEX_SOURCE.indexOf(sourceChars[index*2]) << 4 | HEX_SOURCE.indexOf(sourceChars[index*2 + 1]));
      }
      return buffer;
   }
   
   /**
    * 根据字符串生成**字节数组
    * @param key
    *        **字符串
    * @return
    * @throws Exception
    */
    private static byte[] buildDesKey(String key) throws Exception {
        byte[] keyByte = new byte[24];
        byte[] temp = key.getBytes(ENCODING);
        if (keyByte.length > temp.length) {
           //如果temp不够24位，则拷贝temp数组整个长度的内容到key数组中
            System.arraycopy(temp, 0, keyByte, 0, temp.length);
        } else {
           //如果temp大于24位，则拷贝temp数组24个长度的内容到key数组中
            System.arraycopy(temp, 0, keyByte, 0, keyByte.length);
        }
        return keyByte;
    }

   /**
    * 加密方法
    * @param source
    *        待加密串
    * @param key
    *        秘钥
    * @return
    *        加密后的字符串
    * @throws Exception
    */
   public static String encode(String source, String key) throws Exception {
      byte[] text = source.getBytes(ENCODING);
      Cipher cipher = Cipher.getInstance(ALGORITHM + "/CBC/PKCS5Padding");
      SecretKey secretKey = new SecretKeySpec(buildDesKey(key), ALGORITHM);
      cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(new byte[cipher.getBlockSize()]));
      byte[] cipherBytes = cipher.doFinal(text);
      return byteToHex(cipherBytes);
   }

   /**
    * DES解密方法
    * @param source
    *        待解密的字符串
    * @param key
    *        秘钥
    * @return
    *        解密后的字符串
    * @throws Exception
    */
   public static String decode(String source, String key) throws Exception {
      Cipher cipher = Cipher.getInstance(ALGORITHM + "/CBC/PKCS5Padding");
      SecretKey secretKey = new SecretKeySpec(buildDesKey(key), ALGORITHM);
      cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(new byte[cipher.getBlockSize()]));
      return new String(cipher.doFinal(hexToByte(source)));
   }
}