feat: 초기 구현

README.md

@@ -27,15 +27,16 @@
   - 관측(로그/메트릭/트레이싱)은 엣지/오리진 모두에서 수집
 
 ### 4. APIs (스케치)
-- GET `/{code}`: 코드로 리다이렉트 수행
+- GET `/api/v1/urls/{shortUrl}`: 코드로 리다이렉트 수행
   - 301/302 Location: `<original_url>`
   - 캐시 제어 헤더: 엣지 캐시 가능, 단 TTL/무효화 정책 고려
-- POST `/shorten` (참고): 원본 URL → 단축 코드 생성(본 문서 비스코프)
+- POST `/api/v1/urls` (참고): 원본 URL → 단축 코드 생성(본 문서 비스코프)
 
 ### 5. Data Storage
 - 테이블: `url_mapping`
-  - `code` (PK, 고정 길이 문자열) — 단축 코드, 기본 키 및 인덱스
+  - `id` (PK, 고정 길이 문자열) — 단축 코드, 기본 키 및 인덱스
   - `original_url` (text)
+  - `shortUrl`
   - `created_at`, `expires_at`(선택)
 - 인덱싱
   - B-트리 인덱스(기본) 또는 해시 인덱스(정확 일치 최적화, PostgreSQL 등)

src/main/java/com/example/bitly/controller/UrlController.java

@@ -1,4 +1,58 @@
 package com.example.bitly.controller;
 
+
+import com.example.bitly.controller.dto.UrlCreateRequest;
+import com.example.bitly.service.UrlService;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.responses.ApiResponses;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@Tag(name = "URL 단축 API", description = "URL을 단축하고, 단축된 URL을 원래 URL로 리디렉션하는 API입니다.")
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/api/v1/urls/")
 public class UrlController {
+
+    private final UrlService urlService;
+
+    @Operation(summary = "URL 단축 생성", description = "원본 URL을 받아 단축된 URL을 생성합니다.")
+    @ApiResponses({
+        @ApiResponse(responseCode = "201", description = "단축 URL 생성 성공"),
+        @ApiResponse(responseCode = "400", description = "잘못된 URL 형식")
+    })
+    @PostMapping()
+    public ResponseEntity<String> createShortUrl(@RequestBody UrlCreateRequest request) {
+        String shortUrl = urlService.createShortUrl(request.getOriginalUrl());
+        return ResponseEntity.status(HttpStatus.CREATED).body(shortUrl);
+    }
+
+    @Operation(summary = "원본 URL로 리디렉션", description = "단축 URL을 통해 원본 URL로 리디렉션합니다.")
+    @ApiResponses({
+        @ApiResponse(responseCode = "302", description = "리디렉션 성공"),
+        @ApiResponse(responseCode = "404", description = "존재하지 않는 단축 URL")
+    })
+    @GetMapping("/{shortUrl}")
+    public void redirect(
+        @Parameter(description = "단축 URL", required = true) @PathVariable String shortUrl,
+        HttpServletResponse response) {
+        String originalUrl = urlService.getOriginalUrl(shortUrl);
+        try {
+            response.sendRedirect(originalUrl);
+        } catch (IOException e) {
+            throw new RuntimeException(e); // Checked → Unchecked 변환
+        }
+    }
 }

src/main/java/com/example/bitly/controller/dto/UrlCreateRequest.java

@@ -0,0 +1,10 @@
+package com.example.bitly.controller.dto;
+
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Getter
+@NoArgsConstructor
+public class UrlCreateRequest {
+    private String originalUrl;
+}

src/main/java/com/example/bitly/entity/Url.java

@@ -1,4 +1,33 @@
 package com.example.bitly.entity;
 
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Url {
-}
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false, columnDefinition = "TEXT")
+    private String originalUrl;
+
+    private String shortUrl;
+
+    public Url(String originalUrl) {
+        this.originalUrl = originalUrl;
+    }
+
+    public void setShortUrl(String shortUrl) {
+        this.shortUrl = shortUrl;
+    }
+}

src/main/java/com/example/bitly/repository/UrlRepository.java

@@ -1,4 +1,12 @@
 package com.example.bitly.repository;
 
-public interface UrlRepository {
-}
+import com.example.bitly.entity.Url;
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UrlRepository extends JpaRepository<Url, Long> {
+
+    Optional<Url> findByOriginalUrl(String originalUrl);
+
+    Optional<Url> findByShortUrl(String shortUrl);
+}

src/main/java/com/example/bitly/service/UrlService.java

@@ -1,4 +1,48 @@
 package com.example.bitly.service;
 
+import com.example.bitly.entity.Url;
+import com.example.bitly.repository.UrlRepository;
+import jakarta.persistence.EntityNotFoundException;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
 public class UrlService {
+
+    private final UrlRepository urlRepository;
+    private static final String BASE62_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+    private static final long ID_OFFSET = 1000000000L;
+
+    @Transactional
+    public String createShortUrl(String originalUrl) {
+        // 이미 등록된 URL인지 확인
+        return urlRepository.findByOriginalUrl(originalUrl)
+            .map(Url::getShortUrl)
+            .orElseGet(() -> {
+                Url newUrl = new Url(originalUrl);
+                urlRepository.save(newUrl);
+                String shortUrl = encode(newUrl.getId());
+                newUrl.setShortUrl(shortUrl);
+                return shortUrl;
+            });
+    }
+
+    @Transactional(readOnly = true)
+    public String getOriginalUrl(String shortUrl) {
+        return urlRepository.findByShortUrl(shortUrl)
+            .map(Url::getOriginalUrl)
+            .orElseThrow(() -> new EntityNotFoundException("URL not found for short URL: " + shortUrl));
+    }
+
+    private String encode(long id) {
+        long targetId = id + ID_OFFSET;
+        StringBuilder sb = new StringBuilder();
+        while (targetId > 0) {
+            sb.append(BASE62_CHARS.charAt((int) (targetId % 62)));
+            targetId /= 62;
+        }
+        return sb.reverse().toString();
+    }
 }