java的常用 MD5 DES加密代码【转】

    import java.io.UnsupportedEncodingException;
    import java.security.MessageDigest;

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

    /**
    * 一般加密解密工具<br>
    * DESede/DES/BlowFish<br>
    * DES的密钥(key)长度是为8个字节,加密解密的速度是最快的<br>
    * DESede的密钥(key)长度是24个字节<br>
    * BlowFish的密钥(key)是可变的 加密最快，强度最高,密钥长度范围(1<=key<=16)<br>
    *
    * @author songdawei
    * @version 1.0
    * @date 2008-10-20
    */
    public class SecretCodeUtil {
            public final static String DES = "DES";
            public final static String DESEDE = "DESede";
            public final static String BLOWFISH = "BlowFish";
            public final static String MD5 = "MD5";

            /**
             * md5加密
             *
             * @param plainText
             * @return
             */
            public static String getMD5ofStr(String plainText) {
                    try {
                            return getMD5ofStr(string2Bytes(plainText));
                    } catch (Exception e) {
                            e.printStackTrace();
                    }
                    return null;
            }

            public static String getMD5ofStr(byte str[]) {
                    try {
                            MessageDigest md = MessageDigest.getInstance(MD5);
                            md.update(str);
                            byte b[] = md.digest();
                            return bytes2HexString(b);

                    } catch (Exception e) {
                            e.printStackTrace();
                    }
                    return null;
            }

            /**
             * 对数据源进行加密
             *
             * @param src
             *            数据源
             * @param key
             *            密钥
             * @param name
             *            算法的名称
             * @return 返回加密后的数据
             * @throws Exception
             */
            public static byte[] encrypt(byte[] src, byte[] key, String name)
                            throws Exception {

                    SecretKeySpec securekey = new SecretKeySpec(key, name);
                    // Cipher对象实际完成加密操作
                    Cipher cipher = Cipher.getInstance(name);
                    // 用密匙初始化Cipher对象
                    cipher.init(Cipher.ENCRYPT_MODE, securekey);
                    // 现在，获取数据并加密
                    // 正式执行加密操作
                    return cipher.doFinal(src);
            }

            /**
             * 对加密的数据源进行解密
             *
             * @param src
             *            数据源
             * @param key
             *            密钥
             * @param name
             *            算法的名称
             * @return 返回解密后的原始数据
             * @throws Exception
             */
            public static byte[] decrypt(byte[] src, byte[] key, String name)
                            throws Exception {

                    SecretKeySpec securekey = new SecretKeySpec(key, name);
                    // Cipher对象实际完成解密操作
                    Cipher cipher = Cipher.getInstance(name);
                    // 用密匙初始化Cipher对象
                    cipher.init(Cipher.DECRYPT_MODE, securekey);
                    // 现在，获取数据并解密
                    // 正式执行解密操作
                    return cipher.doFinal(src);
            }

            /**
             * 二行制转字符串
             *
             * @param b
             * @return
             */
            public static String bytes2HexString(byte[] bytes) {
                    String hs = null;
                    if (bytes != null) {
                            final int size = bytes.length;
                            if (size > 0) {
                                    StringBuilder sb = new StringBuilder();
                                    for (int i = 0; i < size; i++) {
                                            String tmp = (java.lang.Integer.toHexString(bytes[i] & 0XFF));
                                            if (tmp.length() == 1) {
                                                    sb.append("0" + tmp);
                                            } else {
                                                    sb.append(tmp);
                                            }
                                    }
                                    hs = sb.toString().toUpperCase();
                            }
                    }
                    return hs;
            }

            public static byte[] hex2byte(byte[] b) {
                    if ((b.length % 2) != 0) {
                            return null;
                    }
                    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;
            }
           
            /**
             * 十六进位格式字符串转二进制流。
             *
             * @param hs String
             * @return byte[]
             */
            public static byte[] hexString2Bytes (String hs) {
                    byte[] bytes = null;
                    if (hs != null) {
                            final int size = (hs.length()) / 2;
                            if (size > 0) {
                                    bytes = new byte[size];
                                    for (int i = 0; i < size; i++) {
                                            String hsByte = hs.substring(i * 2, i * 2 + 2);
                                            byte b = 0;
                                            try {
                                                    b = (byte) (Integer.parseInt(hsByte, 16));
                                            } catch (java.lang.NumberFormatException e) {
                                                    b = 0;
                                            }
                                            bytes[i] = b;
                                    }
                            }
                    }
                    return bytes;
            }

            /**
             * 字符串解密
             *
             * @param data
             *            字符串加密数据
             * @param key
             *            密钥
             * @param name
             *            算法名称
             * @return
             * @throws Exception
             */
            public static String decrypt(String data, String key, String name) {
                    try {
                            return new String(decrypt(hex2byte(data.getBytes()),
                                            string2Bytes(key), name));
                    } catch (Exception e) {

                    }
                    return null;
            }
           
            /**
             * 字符串解密
             *
             * @param data
             *            字符串加密数据
             * @param key
             *            密钥
             * @param name
             *            算法名称
             * @return
             * @throws Exception
             */
            public static String decrypt(String data, byte[] key, String name) {
                    try {
                            return new String(decrypt(hex2byte(data.getBytes()),key, name));
                    } catch (Exception e) {

                    }
                    return null;
            }
           
            /**
             * 把字符串转化成 Unicode Bytes.
             *
             * @param s String
             * @return byte[]
             */
            public static byte [] string2Bytes(String s) {
                    byte[] bytes = null;
                    if (s != null) {
                            try {
                                    bytes = s.getBytes("utf-8");
                            } catch (UnsupportedEncodingException e) {
                                    e.printStackTrace();
                            }
                    }
                    return bytes;
            }

            /**
             * 根据 Unicode Bytes 构造字符串.
             *
             * @param bytes byte[]
             * @return String
             */
            public static String bytes2String (byte[] bytes) {
                    String s = null;
                    if (bytes != null) {
                            try {
                                    s = new String(bytes, "utf-8");
                            } catch (Exception e) {
                                    e.printStackTrace();
                            }
                    }
                    return s;
            }

           
            /**
             * 字符串加密
             *
             * @param data
             *            字符串数据
             * @param key
             *            密钥
             * @param name
             *            算法名称
             * @throws Exception
             */
            public static String encrypt(String data, byte[] key, String name) {
                    try {
                            return bytes2HexString(encrypt(data.getBytes(), key, name));
                    } catch (Exception e) {
                            e.printStackTrace();
                    }
                    return null;
            }
           
            /**
             * 字符串加密
             *
             * @param data
             *            字符串数据
             * @param key
             *            密钥
             * @param name
             *            算法名称
             * @throws Exception
             */
            public static String encrypt(String data, String key, String name) {
                    try {
                            return bytes2HexString(encrypt(data.getBytes(), string2Bytes(key), name));
                    } catch (Exception e) {
                            e.printStackTrace();
                    }
                    return null;
            }
    }