cn.mklaus.framework.util.ShortUrl Maven / Gradle / Ivy

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package cn.mklaus.framework.util;

/**
 * @author Mklaus
 * Created on 2018-01-05 下午1:02
 */
public class ShortUrl {

    public static String[] generate(String url) {
        // 可以自定义生成 MD5 加密字符传前的混合 KEY
        String key = "cn.mkluas.framework" ;
        // 要使用生成 URL 的字符
        String[] chars = new String[] { "a" , "b" , "c" , "d" , "e" , "f" , "g" , "h" ,
                "i" , "j" , "k" , "l" , "m" , "n" , "o" , "p" , "q" , "r" , "s" , "t" ,
                "u" , "v" , "w" , "x" , "y" , "z" , "0" , "1" , "2" , "3" , "4" , "5" ,
                "6" , "7" , "8" , "9" , "A" , "B" , "C" , "D" , "E" , "F" , "G" , "H" ,
                "I" , "J" , "K" , "L" , "M" , "N" , "O" , "P" , "Q" , "R" , "S" , "T" ,
                "U" , "V" , "W" , "X" , "Y" , "Z"

        };
        // 对传入网址进行 MD5 加密
        String sMD5EncryptResult = org.nutz.lang.Lang.md5(key + url);
        String hex = sMD5EncryptResult;

        String[] resUrl = new String[4];
        for ( int i = 0; i < 4; i++) {

            // 把加密字符按照 8 位一组 16 进制与 0x3FFFFFFF 进行位与运算
            String sTempSubString = hex.substring(i * 8, i * 8 + 8);

            // 这里需要使用 long 型来转换，因为 Inteper .parseInt() 只能处理 31 位 , 首位为符号位 , 如果不用 long ，则会越界
            long lHexLong = 0x3FFFFFFF & Long.parseLong (sTempSubString, 16);
            StringBuilder outChars = new StringBuilder() ;
            for ( int j = 0; j < 6; j++) {
                // 把得到的值与 0x0000003D 进行位与运算，取得字符数组 chars 索引
                long index = 0x0000003D & lHexLong;
                // 把取得的字符相加
                outChars.append(chars[( int ) index]);
                // 每次循环按位右移 5 位
                lHexLong = lHexLong >> 5;
            }
            // 把字符串存入对应索引的输出数组
            resUrl[i] = outChars.toString();
        }

        return resUrl;
    }

}