引入以下包才能支持PKCS7Padding

<dependency>
  <groupId>org.bouncycastle</groupId>
  <artifactId>bcprov-jdk15on</artifactId>
  <version>1.55</version>
</dependency>

   public  String  decrypt(String  encryptedData,String  sessionKey)  throws  Exception  {
                encryptedData="UZeNiVw1V11+TQcs4ZHGAMOU6MNAqXE+U8TVA9mJUoE=";
               
     
                //解密之前先把Base64格式的数据转成原始格式
                Base64.Decoder  decoder  =  Base64.getDecoder();
                byte[]  dataByte  =  decoder.decode(encryptedData);
     
                //指定算法，模式，填充方法  创建一个Cipher实例
                Cipher  cipher  =  Cipher.getInstance("DESede/ECB/PKCS7Padding",new  BouncyCastleProvider());

                //生成Key对象
                Key  sKeySpec  =  new  SecretKeySpec(key2,  "DESede");
                //指定用途，密钥，参数  初始化Cipher对象
                cipher.init(Cipher.DECRYPT_MODE,  sKeySpec);

                //执行解密
                byte[]  result  =  cipher.doFinal(dataByte);

                //解密后转成字符串
                data  =  new  String(result);
                logger.info("输出:"+data);

                return  data;
        }

好文
DES加密与3DES加密