/**

 * @author

 *

 */

public class MD5 {

    private static final String[] digital = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e",

            "f" };

    /**

     *

     * <p>

     * Title: initMD5

     * </p>

     * <p>

     * Description: md5加密

     * </p>

     *

     * @param txt

     * @return

     * @throws Exception String

     */

    public static String initMD5(String txt) throws Exception {

        // 获取封装MD5算法的核心类

        MessageDigest md5 = MessageDigest.getInstance("MD5");

        // 将明文经过md5加密后变成长度位16字节的数组----->32位的字符串（16进制）

        byte[] bytes = md5.digest(txt.getBytes("utf-8"));

        // 用来保存最终的密文

        String miWen = "";

        for (byte b : bytes) {

            int temp = b;

            if (temp < 0) {

                temp += 256;

            }

            // 经过判断后，temp一定是正数

            int index1 = temp / 16;// 取商

            int index2 = temp % 16;// 取余

            miWen += digital[index1] + digital[index2];

        }

        return miWen;

    }

    /**

     *

     * <p>Title: finalMD5</p>

     * <p>Description: md5最终加密</p>

     * @param txt

     * @return

     * @throws Exception

     * String

     */

    public static String finalMD5(String txt) throws Exception {

        return initMD5(initMD5(initMD5(txt + "md5" + txt) + "md5" + txt));

    }

    public static void main(String[] args) throws Exception {

        String miWen = MD5.finalMD5("123456");

        System.out.println(miWen);

    }