src/
├── main/
│   ├── java/
│   │   └── com/
│   │       └── example/
│   │           ├── UrlShortenerApplication.java
│   │           ├── controller/
│   │           │   └── UrlController.java
│   │           ├── model/
│   │           │   └── Url.java
│   │           ├── repository/
│   │           │   └── UrlRepository.java
│   │           └── service/
│   │               └── UrlService.java
│   └── resources/
│       └── application.properties

package com.example.model;

import javax.persistence.*;
import java.time.LocalDateTime;

@Entity
public class Url {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String originalUrl;
    private String shortCode;
    private LocalDateTime createdAt;
    private LocalDateTime expiresAt;
    private int visitCount;

    public Url() {}

    public Url(String originalUrl, String shortCode, LocalDateTime createdAt, LocalDateTime expiresAt) {
        this.originalUrl = originalUrl;
        this.shortCode = shortCode;
        this.createdAt = createdAt;
        this.expiresAt = expiresAt;
        this.visitCount = 0;
    }

    // getters and setters
}

package com.example.repository;

import com.example.model.Url;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.Optional;

public interface UrlRepository extends JpaRepository<Url, Long> {
    Optional<Url> findByShortCode(String shortCode);
    void deleteByExpiresAtBefore(LocalDateTime dateTime);
}

package com.example.service;

import com.example.model.Url;
import com.example.repository.UrlRepository;
import org.springframework.stereotype.Service;

import java.time.LocalDateTime;
import java.util.Optional;
import java.util.UUID;

@Service
public class UrlService {
    private final UrlRepository urlRepository;

    public UrlService(UrlRepository urlRepository) {
        this.urlRepository = urlRepository;
    }

    public String shortenUrl(String originalUrl, int expirationDays) {
        String shortCode = UUID.randomUUID().toString().substring(0, 8); // 生成短碼
        LocalDateTime createdAt = LocalDateTime.now();
        LocalDateTime expiresAt = createdAt.plusDays(expirationDays);

        Url url = new Url(originalUrl, shortCode, createdAt, expiresAt);
        urlRepository.save(url);

        return shortCode;
    }

    public Optional<Url> getOriginalUrl(String shortCode) {
        Optional<Url> urlOptional = urlRepository.findByShortCode(shortCode);
        urlOptional.ifPresent(url -> {
            if (url.getExpiresAt().isAfter(LocalDateTime.now())) {
                url.setVisitCount(url.getVisitCount() + 1);
                urlRepository.save(url);
            }
        });
        return urlOptional.filter(url -> url.getExpiresAt().isAfter(LocalDateTime.now()));
    }

    public int getVisitCount(String shortCode) {
        return urlRepository.findByShortCode(shortCode)
                .map(Url::getVisitCount)
                .orElse(0);
    }

    // 定時(shí)任務(wù)清理過(guò)期 URL
    public void cleanUpExpiredUrls() {
        urlRepository.deleteByExpiresAtBefore(LocalDateTime.now());
    }
}

package com.example.controller;

import com.example.model.Url;
import com.example.service.UrlService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.Optional;

@RestController
@RequestMapping("/api/url")
public class UrlController {

    private final UrlService urlService;

    public UrlController(UrlService urlService) {
        this.urlService = urlService;
    }

    @PostMapping("/shorten")
    public ResponseEntity<String> shortenUrl(@RequestParam String originalUrl, @RequestParam(defaultValue = "7") int expirationDays) {
        String shortCode = urlService.shortenUrl(originalUrl, expirationDays);
        return ResponseEntity.ok("Shortened URL: http://localhost:8080/api/url/" + shortCode);
    }

    @GetMapping("/{shortCode}")
    public ResponseEntity<?> redirectUrl(@PathVariable String shortCode) {
        Optional<Url> urlOptional = urlService.getOriginalUrl(shortCode);
        return urlOptional
                .map(url -> ResponseEntity.status(302).header("Location", url.getOriginalUrl()).build())
                .orElse(ResponseEntity.notFound().build());
    }

    @GetMapping("/{shortCode}/stats")
    public ResponseEntity<Integer> getUrlStats(@PathVariable String shortCode) {
        int visitCount = urlService.getVisitCount(shortCode);
        return ResponseEntity.ok(visitCount);
    }
}

package com.example.service;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class CleanupTask {

    private final UrlService urlService;

    public CleanupTask(UrlService urlService) {
        this.urlService = urlService;
    }

    @Scheduled(cron = "0 0 0 * * ?")  // 每天午夜執(zhí)行一次
    public void cleanExpiredUrls() {
        urlService.cleanUpExpiredUrls();
    }
}

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=password
spring.h2.console.enabled=true
spring.jpa.hibernate.ddl-auto=update

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class UrlShortenerApplication {

    public static void main(String[] args) {
        SpringApplication.run(UrlShortenerApplication.class, args);
    }
}