加密机制

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;

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

public class EncryptUtil {
	public static final String ALGORITHM = "SHA-256";
	
	private static final String _KEY = "qwertyuiop1234567890";

	public static String SHA256Encrypt(String orignal) {
		MessageDigest md = null;
		try {
			md = MessageDigest.getInstance(ALGORITHM);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		if (null != md) {
			md.update(orignal.getBytes());
			return getDigestStr(md.digest());
		}
		return null;
	}

	private static String getDigestStr(byte[] origBytes) {
		String tempStr = null;
		StringBuilder stb = new StringBuilder();
		for (int i = 0; i < origBytes.length; i++) {
			tempStr = Integer.toHexString(origBytes[i] & 0xff);
			if (tempStr.length() == 1) {
				stb.append("0");
			}
			stb.append(tempStr);

		}
		return stb.toString();
	}
	
	
	private static final byte[] hex2byte(String hex) throws IllegalArgumentException {
		if (hex.length() % 2 != 0) {
			throw new IllegalArgumentException();
		}
		char[] arr = hex.toCharArray();
		byte[] b = new byte[hex.length() / 2];
		for (int i = 0, j = 0, l = hex.length(); i < l; i++, j++) {
			String swap = "" + arr[i++] + arr[i];
			int byteint = Integer.parseInt(swap, 16) & 0xFF;
			b[j] = new Integer(byteint).byteValue();
		}
		return b;
	}
	
	private static String hexStringToString(String hexString) {
		int encodeType = 2;
		String result = "";
		int max = hexString.length() / encodeType;
		for (int i = 0; i < max; i++) {
			char c = (char)hexStringToAlgorism(hexString.substring(i * encodeType, (i + 1) * encodeType));
			result += c;
		}
		return result;
	}
	
	
	private static int hexStringToAlgorism(String hex) {
        hex = hex.toUpperCase();
        int max = hex.length();
        int result = 0;
        for (int i = max; i > 0; i--) {
            char c = hex.charAt(i - 1);
            int algorism = 0;
            if (c >= '0' && c <= '9') {
                algorism = c - '0';
            } else {
                algorism = c - 55;
            }
            result += Math.pow(16, max - i) * algorism;
        }
        return result;
    }
	
	public static String AESencrypt(String content) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(_KEY.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");
			byte[] byteContent = content.getBytes("utf-8");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] result = cipher.doFinal(byteContent);
			return getDigestStr(result);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	} 
	
	public static String AESdecrypt(String str) {
		
		byte[] content = hex2byte(str);
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(_KEY.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");
			cipher.init(Cipher.DECRYPT_MODE, key);
			byte[] result = cipher.doFinal(content);
			return hexStringToString(getDigestStr(result));
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
	
}