java AES对称加密

import java.io.UnsupportedEncodingException;  
import java.security.InvalidKeyException;  
import java.security.NoSuchAlgorithmException;  
import java.security.SecureRandom;  
  
import javax.crypto.BadPaddingException;  
import javax.crypto.Cipher;  
import javax.crypto.IllegalBlockSizeException;  
import javax.crypto.KeyGenerator;  
import javax.crypto.NoSuchPaddingException;  
import javax.crypto.SecretKey;  
import javax.crypto.spec.SecretKeySpec;  
  
/** 
 * ClassName:AESHelper 
 * 
 * @author   songjianyong 
 * @version  1.0 
 * @since    v1.0 
 * @Date     2012-6-29 下午2:06:07  
 */  
public class AESHelper {  
  
    /** 
     * @method main 
     * @param args 
     * @throws  
     * @since v1.0 
     */  
  
    public static void main(String[] args) {  
  
        String content = "宋建勇";  
        String password = "12345678";  
        byte[] encryptResult = encrypt(content, password);//加密  
        byte[] decryptResult = decrypt(encryptResult,password);//解密  
        System.out.println("解密后：" + new String(decryptResult));  
          
        /*容易出错的地方，请看下面代码*/  
        System.out.println("***********************************************");  
        try {  
            String encryptResultStr = new String(encryptResult,"utf-8");  
            decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password);  
            System.out.println("解密后：" + new String(decryptResult));  
        } catch (UnsupportedEncodingException e) {  
            e.printStackTrace();  
        } catch (Exception e) {  
            // TODO: handle exception  
        }  
        /*则，系统会报出如下异常：javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher 
    at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
    at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
    at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..) 
    at javax.crypto.Cipher.doFinal(DashoA13*..) 
    at cn.com.songjy.test.ASCHelper.decrypt(ASCHelper.java:131) 
    at cn.com.songjy.test.ASCHelper.main(ASCHelper.java:58) 
         * */  
        /*这主要是因为加密后的byte数组是不能强制转换成字符串的, 换言之,字符串和byte数组在这种情况下不是互逆的, 
         * 要避免这种情况，我们需要做一些修订，可以考虑将二进制数据转换成十六进制表示, 
         * 主要有两个方法:将二进制转换成16进制(见方法parseByte2HexStr)或是将16进制转换为二进制(见方法parseHexStr2Byte)*/  
          
        /*然后，我们再修订以上测试代码*/  
        System.out.println("***********************************************");  
        String encryptResultStr = parseByte2HexStr(encryptResult);  
        System.out.println("加密后：" + encryptResultStr);  
        byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);  
        decryptResult = decrypt(decryptFrom,password);//解码  
        System.out.println("解密后：" + new String(decryptResult));  
    }  
  
    /** 
     * 加密 
     * @method encrypt 
     * @param content   需要加密的内容 
     * @param password  加密密码 
     * @return 
     * @throws  
     * @since v1.0 
     */  
    public static byte[] encrypt(String content, String password){  
        try {  
            KeyGenerator kgen = KeyGenerator.getInstance("AES");  
            kgen.init(128, new SecureRandom(password.getBytes()));  
            SecretKey secretKey = kgen.generateKey();  
            byte[] enCodeFormat = secretKey.getEncoded();  
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");  
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器  
            byte[] byteContent = content.getBytes("utf-8");  
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化  
            byte[] result = cipher.doFinal(byteContent);  
            return result; // 加密  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();  
        }catch (NoSuchPaddingException e) {  
            e.printStackTrace();  
        }catch (UnsupportedEncodingException e) {  
            e.printStackTrace();  
        }catch (InvalidKeyException e) {  
            e.printStackTrace();  
        }catch (IllegalBlockSizeException e) {  
            e.printStackTrace();  
        }catch (BadPaddingException e) {  
            e.printStackTrace();  
        }  
        return null;  
    }  
      
    /** 
     * 解密 
     * @method decrypt 
     * @param content   待解密内容 
     * @param password  解密密钥 
     * @return 
     * @throws  
     * @since v1.0 
     */  
    public static byte[] decrypt(byte[] content, String password){  
        try {  
            KeyGenerator kgen = KeyGenerator.getInstance("AES");  
            kgen.init(128, new SecureRandom(password.getBytes()));  
            SecretKey secretKey = kgen.generateKey();  
            byte[] enCodeFormat = secretKey.getEncoded();  
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");  
            Cipher cipher = Cipher.getInstance("AES");// 创建密码器  
            cipher.init(Cipher.DECRYPT_MODE, key);// 初始化  
            byte[] result = cipher.doFinal(content);  
            return result; // 解密  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();  
        }catch (NoSuchPaddingException e) {  
            e.printStackTrace();  
        }catch (InvalidKeyException e) {  
            e.printStackTrace();  
        }catch (IllegalBlockSizeException e) {  
            e.printStackTrace();  
        }catch (BadPaddingException e) {  
            e.printStackTrace();  
        }  
          
        return null;  
    }  
      
    /** 
     * 将二进制转换成16进制 
     * @method parseByte2HexStr 
     * @param buf 
     * @return 
     * @throws  
     * @since v1.0 
     */  
    public static String parseByte2HexStr(byte buf[]){  
        StringBuffer sb = new StringBuffer();  
        for(int i = 0; i < buf.length; i++){  
            String hex = Integer.toHexString(buf[i] & 0xFF);  
            if (hex.length() == 1) {  
                hex = ‘0‘ + hex;  
            }  
            sb.append(hex.toUpperCase());  
        }  
        return sb.toString();  
    }  
      
    /** 
     * 将16进制转换为二进制 
     * @method parseHexStr2Byte 
     * @param hexStr 
     * @return 
     * @throws  
     * @since v1.0 
     */  
    public static byte[] parseHexStr2Byte(String hexStr){  
        if(hexStr.length() < 1)  
            return null;  
        byte[] result = new byte[hexStr.length()/2];  
        for (int i = 0;i< hexStr.length()/2; i++) {  
            int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);  
            int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);  
            result[i] = (byte) (high * 16 + low);  
        }  
        return result;  
    }  
      
    /** 
     * 另外一种加密方式--这种加密方式有两种限制 
     * 1、密钥必须是16位的 
     * 2、待加密内容的长度必须是16的倍数，如果不是16的倍数，就会出如下异常 
     * javax.crypto.IllegalBlockSizeException: Input length not multiple of 16 bytes 
        at com.sun.crypto.provider.SunJCE_f.a(DashoA13*..) 
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
        at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..) 
        at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..) 
        at javax.crypto.Cipher.doFinal(DashoA13*..) 
        要解决如上异常，可以通过补全传入加密内容等方式进行避免。 
     * @method encrypt2 
     * @param content   需要加密的内容 
     * @param password  加密密码 
     * @return 
     * @throws  
     * @since v1.0 
     */  
    public static byte[] encrypt2(String content, String password){  
        try {  
            SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES");  
            Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");  
            byte[] byteContent = content.getBytes("utf-8");  
            cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化  
            byte[] result = cipher.doFinal(byteContent);  
            return result; // 加密  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();  
        } catch (NoSuchPaddingException e) {  
            e.printStackTrace();  
        } catch (UnsupportedEncodingException e) {  
            e.printStackTrace();  
        } catch (InvalidKeyException e) {  
            e.printStackTrace();  
        } catch (IllegalBlockSizeException e) {  
            e.printStackTrace();  
        } catch (BadPaddingException e) {  
            e.printStackTrace();  
        }  
        return null;  
    }  
      
      
}