package com.github.ltsopensource.core.commons.utils;

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

/**
 * @author Robert HG (254963746@qq.com) on 8/1/14.
 */
public class Md5Encrypt {

    /**
     * Used building output as Hex
     */
    private static final char[] DIGITS = {'0', '1', '2', '3', '4', '5', '6',
            '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

    /**
     * MD5编码
     */
    public static String md5(String text) {
        MessageDigest msgDigest = null;

        try {
            msgDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException(
                    "System doesn't support MD5 algorithm.");
        }

        try {
            msgDigest.update(text.getBytes("utf-8"));

        } catch (UnsupportedEncodingException e) {

            throw new IllegalStateException(
                    "System doesn't support your EncodingException.");

        }

        byte[] bytes = msgDigest.digest();

        return new String(encodeHex(bytes));
    }

    public static String md5_16(String sourceStr) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(sourceStr.getBytes());
            byte b[] = md.digest();
            int i;
            StringBuffer buf = new StringBuffer("");
            for (int offset = 0; offset < b.length; offset++) {
                i = b[offset];
                if (i < 0)
                    i += 256;
                if (i < 16)
                    buf.append("0");
                buf.append(Integer.toHexString(i));
            }
            return buf.toString().substring(8, 24);
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException(
                    "System doesn't support MD5 algorithm.");
        }
    }

    private static char[] encodeHex(byte[] data) {
        int l = data.length;

        char[] out = new char[l << 1];

        for (int i = 0, j = 0; i < l; i++) {
            out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
            out[j++] = DIGITS[0x0F & data[i]];
        }
        return out;
    }

}