Java實現短網址應用

1.背景介紹

相信很多人手機上都收到過一些營銷短信，短信里面有時候會附帶一些網址，如下圖

這些網址往往都是非常短，就是我們常說的短網址（短域名）。所以短網址（短域名）服務就是把普通網址，轉換成比較短的網址。在微博以及短信這些限制字數的應用里。好處不言而喻。短、字符少、美觀、便於發布、傳播。

2.原理和應用

其實很簡單 ，系統把一個長的地址 如 http://www.xxx.com/ddd/xxx/a.html?dsada 
首先用一個算法轉換成 短地址 http://t.cn/Afafhe 
然后把  Afafhe-->http://www.xxx.com/ddd/xxx/a.html?dsada 的關系保存下來
當用戶訪問 http://t.cn/Afafhe網址時，系統找到對應的原來的長URL地址，實現跳轉 

3.Java簡單實現的代碼

import com.daqsoft.common.constant.Constants;

import java.security.MessageDigest;
import java.util.Random;

/**
 * 短連接生成工具
 *
 * @author fanhj
 * @version V1.0.0
 * @date 2020-09-09
 */
public class ShortUrlUtils {

    /**
     * 會使用到的常量
     */
    public static final long LONG_0X3FFFFFFF = 0x3FFFFFFF;
    public static final long LONG_0X0000003D = 0x0000003D;
    public static final int LONG_0XFF = 0xFF;

    public static void main(String[] args) {
        // 原始鏈接
        String sLongUrl = "http://www.51bi.com/bbs/_t_278433840/";
        System.out.println("長鏈接:" + sLongUrl);
        // 將產生4組6位字符串
        String[] aResult = shortUrl(sLongUrl);
        // 打印出結果
        for (int i = Constants.INDEX_0; i < aResult.length; i++) {
            System.out.println("[" + i + "]:" + aResult[i]);
        }
        Random random = new Random();
        // 生成4以內隨機數
        int j = random.nextInt(Constants.INDEX_4);
        // 隨機取一個作為短鏈
        System.out.println("短鏈接:" + aResult[j]);
    }

    public static String[] shortUrl(String url) {
        // 可以自定義生成 MD5 加密字符傳前的混合 KEY
        String key = "jkb66.com";
        // 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"
        };
        // 對傳入網址進行 MD5 加密
        String hex = md5ByHex(key + url);

        String[] resUrl = new String[Constants.INDEX_4];
        for (int i = Constants.INDEX_0; i < Constants.INDEX_4; i++) {
            // 把加密字符按照 8 位一組 16 進制與 0x3FFFFFFF 進行位與運算
            String sTempSubString = hex.substring(i * Constants.INDEX_8, i * Constants.INDEX_8 + Constants.INDEX_8);
            // 這里需要使用 long 型來轉換，因為 Integer.parseInt() 只能處理 31 位 , 首位為符號位 ,如果不用long，則會越界
            long lHexLong = LONG_0X3FFFFFFF & Long.parseLong(sTempSubString, Constants.INDEX_16);
            String outChars = "";
            for (int j = Constants.INDEX_0; j < Constants.INDEX_6; j++) {
                // 把得到的值與 0x0000003D 進行位與運算，取得字符數組 chars 索引
                long index = LONG_0X0000003D & lHexLong;
                // 把取得的字符相加
                outChars += chars[(int) index];
                // 每次循環按位右移 5 位
                lHexLong = lHexLong >> Constants.INDEX_5;
            }
            // 把字符串存入對應索引的輸出數組
            resUrl[i] = outChars;
        }
        return resUrl;
    }

    /**
     * MD5加密(32位大寫)
     *
     * @param src 原始字符串
     * @return 加密之后的字符串
     */
    private static String md5ByHex(String src) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] b = src.getBytes();
            md.reset();
            md.update(b);
            byte[] hash = md.digest();
            StringBuffer buffer = new StringBuffer();
            String stmp = "";
            for (int i = Constants.INDEX_0; i < hash.length; i++) {
                stmp = Integer.toHexString(hash[i] & LONG_0XFF);
                if (stmp.length() == Constants.INDEX_1) {
                    buffer.append("0" + stmp);
                } else {
                    buffer.append(stmp);
                }
            }
            return buffer.toString().toUpperCase();
        } catch (Exception e) {
            return "";
        }
    }
}

 

4.Java解析短網址解析與跳轉

import com.alibaba.fastjson.JSONObject;
import com.daqsoft.common.constant.Constants;
import com.daqsoft.common.utils.DateUtil;
import com.daqsoft.framework.support.AbstractCommonController;
import com.daqsoft.framework.support.DataResponse;
import com.daqsoft.zytf.constant.ZytfConstant;
import com.daqsoft.zytf.utils.ShortUrlUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;
import java.util.concurrent.TimeUnit;

/**
 * 短連接請求接受處理Controller
 *
 * @author fanhj
 * @version 1.0.0
 * @date 2020-09-09
 * @since JDK 1.8
 */
@RestController
@RequestMapping("/push")
@CrossOrigin(allowCredentials = "true")
public class PushShortUrlController extends AbstractCommonController {

    @Autowired
    private RedisTemplate redisTemplate;


    /**
     * 前端調用，將原來前端自己拼接成的下載鏈接地址，轉為短連接返回到前端
     *
     * @param request request請求對象
     * @param longUrl 原來前端自己拼接成的下載鏈接地址
     * @return 最近一周數據倒序顯示
     */
    @RequestMapping("/getShortUrl")
    @ResponseBody
    public DataResponse getShortUrl(HttpServletRequest request, String longUrl) {
        String server = "http://" + request.getServerName();
        String[] shortUrlArray = ShortUrlUtils.shortUrl(longUrl);
        String shortUrl = server + "/push/" + shortUrlArray[Constants.INDEX_4];
        ValueOperations<String, Map> opsForValue = redisTemplate.opsForValue();
        Map<String, Object> map = new HashMap<String, Object>(Constants.INDEX_4);
        // 緩存的短連接 對應的原始鏈接
        map.put("longUrl", longUrl);
        // 緩存的短連接的創建時間
        map.put("createTime", DateUtil.getCurrentDateTime());
        // 緩存的短連接的字符串內容
        map.put("shortUrl", shortUrl);
        // 緩存7天 也可以在此記錄短網址的點擊量等數據
        opsForValue.set("short_url_" + shortUrl, map, Constants.INDEX_7, TimeUnit.DAYS);
        JSONObject resultJson = new JSONObject();
        resultJson.put("shortUrl", shortUrl);
        return succeed(resultJson);
    }

    /**
     * 短連接請求接受處理處
     *
     * @param id       短連接內容
     * @param request  request請求對象
     * @param response response輸出對象
     * @throws IOException 拋出的異常
     */
    @RequestMapping(value = "/{id}")
    public void url(@PathVariable String id, HttpServletRequest request,
                    HttpServletResponse response) throws IOException {
        //獲得客戶端發送請求的完整url 即我們的短連接
        String shortUrlStr = request.getRequestURL().toString();
        ValueOperations<String, Map> opsForValue = redisTemplate.opsForValue();
        Map<String, Object> map = opsForValue.get("short_url_" + shortUrlStr);
        if (map == null) {
            response.sendError(ZytfConstant.INDEX_404, "鏈接已過期失效");
            return;
        }
        String longUrl = map.get("longUrl").toString();
        if (StringUtils.isEmpty(longUrl)) {
            response.sendError(ZytfConstant.INDEX_404, "鏈接已過期失效");
            return;
        } else {
            response.sendRedirect(longUrl);
            return;
        }
    }
}