java兑现md5和aes加密解密

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Util {

/**
* 通过MD5加密算法返回加密后的字符串
*
* @param text 明文（要加密的字符串）
* @return
*/
public static String createMD5(String text) {
MessageDigest md = null;
try {
md = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {// 理论上不会有这个异常
throw new IllegalStateException("System doesn't support MD5 algorithm.");
}
md.update(text.getBytes());
byte b[] = md.digest();
StringBuffer buf = new StringBuffer("");
for (int offset = 0; offset < b.length; offset++) {
int i = b[offset];
if (i < 0) {
i += 256;
}
if (i < 16) {
buf.append("0");// 不足两位，补0
}
buf.append(Integer.toHexString(i));
}
return buf.toString();
}

}

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

/**
* This program generates a AES key, retrieves its raw bytes, and then reinstantiates a AES key from the key bytes. The
* reinstantiated key is used to initialize a AES cipher for encryption and decryption.
*/
public class AES {

private static final String AES = "AES";

private static final String CRYPT_KEY = "YUUAtestYUUAtest";

/**
* 加密
*
* @param encryptStr
* @return
*/
public static byte[] encrypt(byte[] src, String key) throws Exception {
Cipher cipher = Cipher.getInstance(AES);
SecretKeySpec securekey = new SecretKeySpec(key.getBytes(), AES);
cipher.init(Cipher.ENCRYPT_MODE, securekey);// 设置密钥和加密形式
return cipher.doFinal(src);
}

/**
* 解密
*
* @param decryptStr
* @return
* @throws Exception
*/
public static byte[] decrypt(byte[] src, String key) throws Exception {
Cipher cipher = Cipher.getInstance(AES);
SecretKeySpec securekey = new SecretKeySpec(key.getBytes(), AES);// 设置加密Key
cipher.init(Cipher.DECRYPT_MODE, securekey);// 设置密钥和解密形式
return cipher.doFinal(src);
}

/**
* 二行制转十六进制字符串
*
* @param b
* @return
*/
public static String byte2hex(byte[] b) {
String hs = "";
String stmp = "";
for (int n = 0; n < b.length; n++) {
stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
if (stmp.length() == 1) hs = hs + "0" + stmp;
else hs = hs + stmp;
}
return hs.toUpperCase();
}

public static byte[] hex2byte(byte[] b) {
if ((b.length % 2) != 0) throw new IllegalArgumentException("长度不是偶数");
byte[] b2 = new byte[b.length / 2];
for (int n = 0; n < b.length; n += 2) {
String item = new String(b, n, 2);
b2[n / 2] = (byte) Integer.parseInt(item, 16);
}
return b2;
}

/**
* 解密
*
* @param data
* @return
* @throws Exception
*/
public final static String decrypt(String data) {
try {
return new String(decrypt(hex2byte(data.getBytes()), CRYPT_KEY));
} catch (Exception e) {
}
return null;
}

/**
* 加密
*
* @param data
* @return
* @throws Exception
*/
public final static String encrypt(String data) {
try {
return byte2hex(encrypt(data.getBytes(), CRYPT_KEY));
} catch (Exception e) {
}
return null;
}

public static void main(String[] args) {
String ID = "11112222";

String idEncrypt = encrypt(ID);
System.out.println(idEncrypt);
String idDecrypt = decrypt(idEncrypt);
System.out.println(idDecrypt);
}

}