java加密解密

package com.neo.xnol.weixin.util;

import java.security.Key;
import java.security.Security;

import javax.crypto.Cipher;

public class DesSecurityUtil {
    private static String strDefaultKey = "national";

    public static Cipher encryptCipher = null;

    public static Cipher decryptCipher = null;

    /**
     * 将byte数组转换为表示16进制值的字符串 hexStr2ByteArr(String strIn) 互为可逆的转换过程 需要转换的byte数组 28. *
     * 
     * @return 转换后的字符串 29. *
     * @throws Exception
     */
    public static String byteArr2HexStr(final byte[] arrB) throws Exception {
        int iLen = arrB.length;
        // 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
        StringBuffer sb = new StringBuffer(iLen * 2);
        for (int i = 0; i < iLen; i++) {
            int intTmp = arrB[i];
            // 把负数转换为正数
            while (intTmp < 0) {
                intTmp = intTmp + 256;
            }
            // 小于0F的数需要在前面补0
            if (intTmp < 16) {
                sb.append("0");
            }
            sb.append(Integer.toString(intTmp, 16));
        }
        return sb.toString();
    }

    /**
     * 将表示16进制值的字符串转换为byte数组， 和public static String byteArr2HexStr(byte[] arrB) 互为可逆的转换过程
     * 
     * @param strIn 需要转换的字符串
     * @return 转换后的byte数组
     * @throws Exception
     */
    public static byte[] hexStr2ByteArr(final String strIn) throws Exception {
        byte[] arrB = strIn.getBytes();
        int iLen = arrB.length;

        // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
        byte[] arrOut = new byte[iLen / 2];
        for (int i = 0; i < iLen; i = i + 2) {
            String strTmp = new String(arrB, i, 2);
            arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
        }
        return arrOut;
    }

    /**
     * 默认构造方法，使用默认密钥
     * 
     * @throws Exception
     */
    public DesSecurityUtil() throws Exception {
        this(strDefaultKey);
    }

    /**
     * 指定密钥构造方法 86. * 87. *
     * 
     * @param strKey 指定的密钥
     * @throws Exception
     */
    @SuppressWarnings("restriction")
    public DesSecurityUtil(final String strKey) throws Exception {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        Key key = getKey(strKey.getBytes());

        encryptCipher = Cipher.getInstance("DES");
        encryptCipher.init(Cipher.ENCRYPT_MODE, key);

        decryptCipher = Cipher.getInstance("DES");
        decryptCipher.init(Cipher.DECRYPT_MODE, key);
    }

    /**
     * 初始化参数
     * 
     * @param strKey
     * @throws Exception
     */
    @SuppressWarnings("restriction")
    private static void init(final String strKey) throws Exception {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        Key key = getKey(strKey.getBytes());

        encryptCipher = Cipher.getInstance("DES");
        encryptCipher.init(Cipher.ENCRYPT_MODE, key);

        decryptCipher = Cipher.getInstance("DES");
        decryptCipher.init(Cipher.DECRYPT_MODE, key);
    }

    /**
     * 加密字节数组
     * 
     * @param arrB 需加密的字节数组
     * @return 加密后的字节数组
     * @throws Exception
     */
    public static byte[] encrypt(final byte[] arrB) throws Exception {
        return encryptCipher.doFinal(arrB);
    }

    /**
     * 加密字符串
     * 
     * @param strIn 需加密的字符串 119. *
     * @return 加密后的字符串
     * @throws Exception
     */
    public static String encrypt(final String strIn) throws Exception {
        DesSecurityUtil.init(strDefaultKey);
        return byteArr2HexStr(encrypt(strIn.getBytes()));
    }

    /**
     * 解密字节数组
     * 
     * @param arrB 需解密的字节数组
     * @return 解密后的字节数组
     * @throws Exception
     */
    public static byte[] decrypt(final byte[] arrB) throws Exception {
        return decryptCipher.doFinal(arrB);
    }

    /**
     * 解密字符串
     * 
     * @param strIn 需解密的字符串
     * @return 解密后的字符串
     * @throws Exception
     */
    public static String decrypt(final String strIn) throws Exception {
        DesSecurityUtil.init(strDefaultKey);
        return new String(decrypt(hexStr2ByteArr(strIn)));
    }

    /**
     * 从指定字符串生成密钥，密钥所需的字节数组长度为8位 不足8位时后面补0，超出8位只取前8位
     * 
     * @param arrBTmp 构成该字符串的字节数组
     * @return 生成的密钥
     * @throws java.lang.Exception
     */
    private static Key getKey(final byte[] arrBTmp) throws Exception {
        // 创建一个空的8位字节数组（默认值为0）
        byte[] arrB = new byte[8];

        // 将原始字节数组转换为8位
        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
            arrB[i] = arrBTmp[i];
        }

        // 生成密钥
        Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");

        return key;
    }
}