以下加密在android4.4版本上运行正常，但是在低于4.4版本上的设备，每次结果不一样。希望有人能帮我解决这个问题，谢谢！
public String encryptPass(){
String username="stackoverflow";
String password="stackoverflow";
String salt="stackoverflow145";
PBEKeySpec keySpec=new PBEKeySpec(username.toCharArray(),salt.getBytes(),1000,256);
SecretKeyFactory keyFactory=SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
SecretKey key=keyFactory.generateSecret(keySpec);
/*初始向量：16位长度*/
byte[] iv={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
IvParameterSpec ivSpec=new IvParameterSpec(iv);
Cipher cipher=Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE,key,ivSpec);
byte[] passBytes=cipher.doFinal(password.getBytes());
String result=Base64.encodeToString(passBytes,Base64.NO_WRAP);
return result;
}
