主要是用于加密，加密是可逆的，可以加密也可以解密。

import java.security.NoSuchAlgorithmException;     import javax.crypto.Cipher;  import javax.crypto.NoSuchPaddingException;  import javax.crypto.spec.IvParameterSpec;  import javax.crypto.spec.SecretKeySpec;     public class JiaMi {         private String iv = "feie91o96t2q2p0p";      private IvParameterSpec ivspec;      private SecretKeySpec keyspec;      private Cipher cipher;             private String SecretKey = "8d0bfe2fb0311fd7";             public JiaMi()      {          ivspec = new IvParameterSpec(iv.getBytes());             keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");                     try {              cipher = Cipher.getInstance("AES/CBC/NoPadding");          } catch (NoSuchAlgorithmException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchPaddingException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }      }             public byte[] encrypt(String text) throws Exception      {          if(text == null || text.length() == 0)              throw new Exception("Empty string");                     byte[] encrypted = null;             try {              cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);                 encrypted = cipher.doFinal(padString(text).getBytes());          } catch (Exception e)          {                        throw new Exception("[encrypt] " + e.getMessage());          }                     return encrypted;      }             public byte[] decrypt(String code) throws Exception      {          if(code == null || code.length() == 0)              throw new Exception("Empty string");                     byte[] decrypted = null;             try {              cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);                             decrypted = cipher.doFinal(hexToBytes(code));          } catch (Exception e)          {              throw new Exception("[decrypt] " + e.getMessage());          }          return decrypted;      }                       public static String bytesToHex(byte[] data)      {          if (data==null)          {              return null;          }                     int len = data.length;          String str = "";          for (int i=0; i<len; i++) {              if ((data[i]&0xFF)<16)                  str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);              else                  str = str + java.lang.Integer.toHexString(data[i]&0xFF);          }          return str;      }                        public static byte[] hexToBytes(String str) {          if (str==null) {              return null;          } else if (str.length() < 2) {              return null;          } else {              int len = str.length() / 2;              byte[] buffer = new byte[len];              for (int i=0; i<len; i++) {                  buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);              }              return buffer;          }      }                       private static String padString(String source)      {        char paddingChar = ' ';        int size = 16;        int x = source.length() % size;        int padLength = size - x;           for (int i = 0; i < padLength; i++)        {            source += paddingChar;        }           return source;      }  }  //使用方法：  //加密  String      encrypted = JiaMi.bytesToHex(jm.encrypt("你要加密的内容"));  //解密     String decrypted = new String(JiaMi.decrypt(encrypted));