CryptUtil

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/**
 * 加密、解密工具类 包装cipher对象的操作
 * 基于javax.crypto.*、java.security.*、org.apache.commons.codec.binary.Base64实现
 * 解密、加密包装。该工具类仅仅是对底层方法的包装，提供更友好的API使用，本身不包含任何加密、解密
 * 算法；所有加密、解密算法均依赖于JDK提供的包实现；
 * 
 * @author chenxin
 * @version [版本号, 2012-5-21]
 * @see [相关类/方法]
 * @since [产品/模块版本]
 */
public class CryptUtil {

	/**
	 * 单态实例对象
	 */
	private static final CryptUtil instance = new CryptUtil();

	/**
	 * Base64解码对象
	 */
	private static final BASE64Decoder base64De = new BASE64Decoder();
	
	/**
	 * Base64加码对象
	 */
	private static final BASE64Encoder base64En = new BASE64Encoder();
	
	/**
	 * 密码类型
	 * @author ahli
	 * @version IMPV100R001DA0, Nov 18, 2009 
	 * @since CMS IMPV100R001DA0
	 */
	public enum CipherType{
		AES,
		DES
	}
	
	/**
	 * 私有构造函数，避免被外部实例化
	 */
	private CryptUtil()
	{
	};

	/**
	 * 获取单态实例对象
	 * @return
	 */
	public static CryptUtil getInstance()
	{
		return instance;
	}

	/**
	 * 产生随机的密钥
	 * 例如：“xjPk2rOSU1n5v70a84M+vw==”
	 * @return    随机密钥
	 */
	public String genRandomKeyStr(CipherType type)
	{
		SecretKey key;
		try
		{
			key = KeyGenerator.getInstance(type.toString()).generateKey();
			return base64En.encode(key.getEncoded());
		}
		catch (NoSuchAlgorithmException e)
		{
			return null;
		}
	}

	/**
	 * 加密文本
	 * @param str      明文
	 * @param key      密钥
	 * @param type     密码类型
	 * @return         密文
	 */
	public String encrypt(String str, String key, CipherType type)
	{
		try
		{
			Cipher cipher = Cipher.getInstance(type.toString());
			cipher.init(Cipher.ENCRYPT_MODE, initKey(type.toString(), key));
			return new String(Base64.encodeBase64(cipher.doFinal(str.getBytes("UTF-8"))));
		}
		catch (IOException e)
		{
			e.printStackTrace();
		}
		catch (GeneralSecurityException e)
		{
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 解密
	 * @param str     密文
	 * @param key     密钥
	 * @param type    密码算法
	 * @return        明文
	 */
	public String decrypt(String str, String key, CipherType type)
	{
		try
		{
			Cipher cipher = Cipher.getInstance(type.toString());
			cipher.init(Cipher.DECRYPT_MODE, initKey(type.toString(), key));
			return new String(cipher.doFinal( base64De.decodeBuffer(str)), "UTF-8");
		}
		catch (IOException e)
		{
			e.printStackTrace();
		}
		catch (GeneralSecurityException e)
		{
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 初始化密钥
	 * @param cryptType    加密算法类型
	 * @param key          密钥
	 * @return
	 * @throws UnsupportedEncodingException
	 */
	private Key initKey(String cryptType, String key) throws UnsupportedEncodingException{
		SecretKey secretKey = new SecretKeySpec(Base64.decodeBase64(key.getBytes("UTF-8")), cryptType);
		return secretKey;
	}
	
	public static void main(String[] args)
	{
//		String randomKey = CryptUtil.getInstance().genRandomKeyStr(CipherType.AES);
		String randomKey = "C1ZZsBNd0JY/8Yx2nPEg2g==";
		System.out.println("randomKey:" + randomKey);
		String message = "cms4a";
		System.out.println("加密前明文:" + message);
		String s1 = CryptUtil.getInstance().encrypt(message, randomKey, CipherType.AES);
		System.out.println("加密后的信息：" + s1);
		String s2 = CryptUtil.getInstance().decrypt(s1, randomKey, CipherType.AES);
		System.out.println("解密后的信息：" + s2);
	}


}