java加密解密類

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("你要加密的內容"));
//解密
String decrypted = new String(JiaMi.decrypt(encrypted));</pre>