Implementing Short URL Redirection with SpringBoot

Background

Short‑URL redirection converts long web links into compact URLs that are easier to share, display and track. Third‑party services typically generate a short link that redirects to the original long URL and may provide click statistics.

Significance

Space saving: Short links reduce character count for sharing.

Link beautification: They appear cleaner and more attractive.

Link stability: Short links can be updated behind the scenes to avoid broken URLs.

Analytics: Click counts, sources and regions can be tracked.

Ease of sharing: Short links copy and paste easily across platforms.

Privacy: Original URL details can be hidden.

SpringBoot Implementation

1. Database Table

A table t_url_map stores the mapping between long URLs, short URLs, the owning username and timestamps.

2. Mapping Entity

import lombok.AllArgsConstructor;<br/>import lombok.Builder;<br/>import lombok.Data;<br/>import lombok.NoArgsConstructor;<br/><br/>import java.time.Instant;<br/><br/>@Data<br/>@Builder<br/>@AllArgsConstructor<br/>@NoArgsConstructor<br/>public class UrlMap {<br/>    private Long id;<br/>    private String longUrl;<br/>    private String shortUrl;<br/>    private String username;<br/>    private Instant expireTime;<br/>    private Instant creationTime;<br/>}

3. DAO Layer

import com.zhan.zhan215.Entity.UrlMap;<br/>import org.apache.ibatis.annotations.Mapper;<br/>import org.apache.ibatis.annotations.Param;<br/><br/>@Mapper<br/>public interface UrlMapMapper {<br/>    UrlMap findFirstByLongUrl(@Param("longUrl") String longUrl, @Param("username") String username);<br/>    void saveUrlMap(UrlMap urlMap);<br/>    UrlMap findByShortUrl(String shortUrl);<br/>}

The corresponding MyBatis XML defines select and insert statements for the above methods.

4. Service Layer

import com.zhan.zhan215.Dao.UrlMapMapper;<br/>import com.zhan.zhan215.Entity.UrlMap;<br/>import org.springframework.stereotype.Service;<br/><br/>import javax.annotation.Resource;<br/>import java.security.MessageDigest;<br/>import java.security.NoSuchAlgorithmException;<br/>import java.time.Instant;<br/><br/>@Service<br/>public class UrlMapService {<br/>    @Resource<br/>    private UrlMapMapper urlMapMapper;<br/><br/>    // Encode long URL to short URL<br/>    public String encode(String longUrl, String username) {<br/>        UrlMap urlMap = urlMapMapper.findFirstByLongUrl(longUrl, username);<br/>        if (urlMap != null && username.equals(urlMap.getUsername())) {<br/>            return urlMap.getShortUrl();<br/>        } else {<br/>            String shortLink = generateShortLink(longUrl, username);<br/>            UrlMap newMap = new UrlMap();<br/>            newMap.setLongUrl(longUrl);<br/>            newMap.setShortUrl(shortLink);<br/>            newMap.setUsername(username);<br/>            newMap.setCreationTime(Instant.now());<br/>            urlMapMapper.saveUrlMap(newMap);<br/>            return shortLink;<br/>        }<br/>    }<br/><br/>    // Decode short URL to long URL<br/>    public String decode(String shortUrl) {<br/>        UrlMap map = urlMapMapper.findByShortUrl(shortUrl);<br/>        return map != null ? map.getLongUrl() : "https://bilibili.com";<br/>    }<br/><br/>    // Generate short link using MD5 hash (first 8 chars) plus username<br/>    public static String generateShortLink(String originalUrl, String username) {<br/>        try {<br/>            MessageDigest md = MessageDigest.getInstance("MD5");<br/>            byte[] hash = md.digest(originalUrl.getBytes());<br/>            StringBuilder sb = new StringBuilder();<br/>            for (byte b : hash) { sb.append(String.format("%02x", b)); }<br/>            return sb.toString().substring(0, 8) + username;<br/>        } catch (NoSuchAlgorithmException e) { e.printStackTrace(); return null; }<br/>    }<br/>}

5. Controller Layer

import com.zhan.zhan215.Common.ResponseBean;<br/>import com.zhan.zhan215.Service.UrlMapService;<br/>import org.springframework.web.bind.annotation.GetMapping;<br/>import org.springframework.web.bind.annotation.PostMapping;<br/>import org.springframework.web.bind.annotation.RequestParam;<br/>import org.springframework.web.bind.annotation.RestController;<br/>import org.springframework.web.servlet.view.RedirectView;<br/><br/>import javax.annotation.Resource;<br/><br/>@RestController<br/>public class UrlMapController {<br/>    @Resource<br/>    private UrlMapService urlMapService;<br/><br/>    @PostMapping("/shorten")
    public ResponseBean shorten(@RequestParam String longUrl, @RequestParam String username) {<br/>        String short = urlMapService.encode(longUrl, username);<br/>        return ResponseBean.success(short);<br/>    }<br/><br/>    @GetMapping("redirect")
    public RedirectView redirectView(@RequestParam String shortUrl) {<br/>        String longUrl = urlMapService.decode(shortUrl);<br/>        return new RedirectView(longUrl);<br/>    }<br/>}

6. Response Wrapper

public class ResponseBean<T> {<br/>    private boolean success;<br/>    private T data;<br/>    // getters and setters omitted for brevity<br/>    public static <T> ResponseBean<T> success(T data) {<br/>        ResponseBean<T> r = new ResponseBean<>();<br/>        r.setSuccess(true); r.setData(data); return r;<br/>    }<br/>    public static <T> ResponseBean<T> error(T errorData) {<br/>        ResponseBean<T> r = new ResponseBean<>();<br/>        r.setSuccess(false); r.setData(errorData); return r;<br/>    }<br/>}

Result Testing

A sample Bilibili video URL is shortened to a value such as 1b9590bezhan. Accessing the short link correctly redirects to the original long URL, confirming the implementation works.

Discussion

The username parameter is included so that different users generating a short link for the same long URL receive distinct short URLs, enabling per‑user tracking and analytics.