@Java讲坛杨33

引入加解密的目的

实际开发中，经常涉及一些业务数据是具有隐私性的，并且不情愿被外人看到这些隐私信息。所以使用Java语言开发，就必须在开发具体业务逻辑代码的时候，引入加解密的工具，把隐私数据保护起来。

下面就用编码封装我常用的两个加解密工具类DES、AES。

DES加解密

DES是一种对称的加解密算法。对称的意思就是加密和解密使用的密钥key是相同的。

直接上工具类代码：

import javax.crypto.Cipher;import javax.crypto.SecretKey;import javax.crypto.spec.IvParameterSpec;import javax.crypto.spec.SecretKeySpec;/** * DES加解密工具类 */public class Des3Util {	private static final String ALGORITHM = "DESede";	private static final String ENCODING = "UTF-8";	private static final String HEX_SOURCE = "0123456789ABCDEF";	/**	 * 字节码转十六进制字符串	 * @param sources 字节码	 * @return	 */	private static String byteToHex(byte[] sources) {		if(sources == null || sources.length == 0){			return null;		}		StringBuffer result = new StringBuffer();		for(byte source : sources){			String tmp = (Integer.toHexString(source & 0XFF));			if(tmp.length() == 1){				result.append("0" + tmp);			}else{				result.append(tmp);			}		}		return result.toString().toUpperCase();	}	/**	 * 十六进制字符串转字节码	 * @param source 十六进制字符串	 * @return	 */	public static byte[] hexToByte(String source) {		if(source.length() % 2 != 0){			throw new IllegalArgumentException("给定的十六进制字符串的长度不是偶数");		}		char[] sourceChars = source.toUpperCase().toCharArray();		int length = sourceChars.length/2;		byte buffer[] = new byte[length];		for(int index = 0;index < length; index++) {			buffer[index] = (byte) (HEX_SOURCE.indexOf(sourceChars[index*2]) << 4 | HEX_SOURCE.indexOf(sourceChars[index*2 + 1]));		}		return buffer;	}		/**	 * 根据密钥字符串生成密钥字节数组	 * @param key 密钥	 * @return 密钥字节数组	 * @throws Exception	 */    private static byte[] buildDesKey(String key) throws Exception {        byte[] keyByte = new byte[24];        byte[] temp = key.getBytes(ENCODING);        if (keyByte.length > temp.length) {        	//如果temp不够24位，则拷贝temp数组整个长度的内容到key数组中            System.arraycopy(temp, 0, keyByte, 0, temp.length);        } else {        	//如果temp大于24位，则拷贝temp数组24个长度的内容到key数组中            System.arraycopy(temp, 0, keyByte, 0, keyByte.length);        }        return keyByte;    }	/**	 * 加密	 * @param source 待加密的字符串	 * @param key 密钥	 * @return 加密后的字符串	 * @throws Exception	 */	public static String encode(String source, String key) throws Exception {		byte[] text = source.getBytes(ENCODING);		Cipher cipher = Cipher.getInstance(ALGORITHM + "/CBC/PKCS5Padding");		SecretKey secretKey = new SecretKeySpec(buildDesKey(key), ALGORITHM);		cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(new byte[cipher.getBlockSize()]));		byte[] cipherBytes = cipher.doFinal(text);		return byteToHex(cipherBytes);	}	/**	 * 解密	 * @param source 待解密的加密串	 * @param key 密钥	 * @return 解密后的字符串	 * @throws Exception	 */	public static String decode(String source, String key) throws Exception {		Cipher cipher = Cipher.getInstance(ALGORITHM + "/CBC/PKCS5Padding");		SecretKey secretKey = new SecretKeySpec(buildDesKey(key), ALGORITHM);		cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(new byte[cipher.getBlockSize()]));		return new String(cipher.doFinal(hexToByte(source)));	}	/**	 * 测试DES加解密	 * @param args	 * @throws Exception	 */	public static void main(String[] args) throws Exception {		String key = "8681d91f1d56458385c9fc23b221828b";		//加密		System.out.println(encode("马云", key));		//解密		System.out.println(decode("1E27D89F0421A8A6", key));	}}

AES是DES的加强版，比DES的加解密强度更高。

直接上工具类代码：

import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.spec.SecretKeySpec;/** * AES加解密工具类 */public class AesUtil {	/**	 * 秘钥长度	 */	private static final int keysize = 128;	/**	 * 加密方式	 */	private static final String algorithm = "AES";	/**	 * 编码方式	 */	private static final String charSet = "UTF-8";	/**	 * 十六进制字符	 */	private static final String HEX_SOURCE = "0123456789ABCDEF";		/**	 * 加密	 * @param source 待加密字符串	 * @param key 秘钥	 * @return 加密完的十六进制字符串；如果加密失败返回空	 */	public static String encrypt(String source, String key) {  		if(source == null || source.trim().length() == 0 				|| key == null || key.trim().length() == 0){			return null;		}		try{			KeyGenerator keyGenerator = KeyGenerator.getInstance(algorithm);  			SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");			secureRandom.setSeed(key.getBytes());			keyGenerator.init(keysize, secureRandom);			SecretKeySpec secretKeySpec = new SecretKeySpec(keyGenerator.generateKey().getEncoded(), algorithm);			Cipher cipher = Cipher.getInstance(algorithm);			cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);			byte[] sourceByte = cipher.doFinal(source.getBytes(charSet));			return byteToHex(sourceByte);		}catch(Exception e){			System.err.println(e);			return null;		}	}  		/**	 * 解密	 * @param source 待解密十六进制字符串	 * @param key 秘钥	 * @return 加密后的字符串；如果解密失败返回null	 */	public static String decrypt(String source, String key) {  		if(source == null || source.trim().length() == 0 				|| key == null || key.trim().length() == 0){			return null;		}		try{			byte[] sourceByte = hexToByte(source);  			KeyGenerator keyGenerator = KeyGenerator.getInstance(algorithm);			SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");			secureRandom.setSeed(key.getBytes());			keyGenerator.init(keysize, secureRandom);			SecretKeySpec secretKeySpec = new SecretKeySpec(keyGenerator.generateKey().getEncoded(), algorithm);			Cipher cipher = Cipher.getInstance(algorithm);			cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);			return new String(cipher.doFinal(sourceByte),"UTF-8");		}catch(Exception e){			return null;		}	}		/**	 * 字节码转十六进制字符串	 * @param sources 字节码	 * @return	 */	private static String byteToHex(byte[] sources) {		if(sources == null || sources.length == 0){			return null;		}		StringBuffer result = new StringBuffer();		for(byte source : sources){			String tmp = (Integer.toHexString(source & 0XFF));			if(tmp.length() == 1){				result.append("0" + tmp);			}else{				result.append(tmp);			}		}		return result.toString().toUpperCase();	}	/**	 * 十六进制字符串转字节码	 * @param source 十六进制字符串	 * @return	 */	private static byte[] hexToByte(String source){		if(source.length() % 2 != 0){			throw new IllegalArgumentException("给定的十六进制字符串的长度不是偶数");		}		char[] sourceChars = source.toUpperCase().toCharArray();		int length = sourceChars.length/2;		byte buffer[] = new byte[length];		for(int index = 0;index < length;index++) {			buffer[index] = (byte) (HEX_SOURCE.indexOf(sourceChars[index*2]) << 4 | HEX_SOURCE.indexOf(sourceChars[index*2 + 1]));		}		return buffer;	}	/**	 * 测试AES加解密	 * @param args	 */	public static void main(String[] args) {		String key = "8681d91f1d56458385c9fc23b221828b";		//加密		System.out.println(encrypt("马云", key));		//解密		System.out.println(decrypt("DBBDAAE0F2B2999E0CA47CB3B7698C38", key));	}}

到此，本次知识分享就结束了，谢谢大家对我的创作方面的鼓励。我会继续努力。

作者：杨33，北京互联网公司在职Java开发，专注分享写作干货。欢迎关注我，期待你的点赞评论。