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專案已託管於 GitHub：y0ngb1n/spring-boot-samples，歡迎 Star,Fork ?

準備工作

• Spring Boot 2.1.0+
• Redis
• Lombok
• Guava 28.0
• Common Validator 1.6

新增依賴項

pom.xml

<dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId
 
>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-redis</artifactId>
    </dependency>

    <dependency>
      <groupId
 
>commons-validator</groupId>
      <artifactId>commons-validator</artifactId>
    </dependency>

    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
    </dependency>
</dependencies>
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application.yml

spring:
  # Redis Config
  redis:
    url: 127.0.0.1
    port: 6379
    password: your_password

logging:
  level:
    io.github.y0ngb1n.*: debug
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核心程式碼

/**
 * URL Shortener Resource
 *
 * @author yangbin
 */
@Slf4j
@RestController
@RequestMapping(path = "/v1")
public class UrlShortenerController {

  @Autowired
  StringRedisTemplate redisTemplate;

  @GetMapping(path = "/{id}")
  public String getUrl(@PathVariable String id) {
+   String url = redisTemplate.opsForValue().get(id);
    log.debug("URL Retrieved: {}",url);
    return url;
  }

  @PostMapping
  public String create(@RequestBody String url) {
    UrlValidator urlValidator = new UrlValidator(
      new String[]{"http","https"}
    );
    if (urlValidator.isValid(url)) {
-     String id = Hashing.murmur3_32().hashString(url,StandardCharsets.UTF_8).toString();
      log.debug("URL Id generated: {}",id);
+     redisTemplate.opsForValue().set(id,url);
      return id;
    }
    throw new RuntimeException("URL Invalid: " + url);
  }
}
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使用方式

Step 0: 安裝並啟動 Redis

# on Windows
scoop install redis
redis-server

# on Mac
brew install redis
redis-server
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Step 1: 啟動 url-shortener 服務

$ mvn install
...
[INFO] BUILD SUCCESS
...
$ mvn spring-boot:run
...
2019-08-21 21:03:50.215  INFO 10244 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2019-08-21 21:03:50.219  INFO 10244 --- [ main] i.g.y.s.u.UrlShortenerApplication        : Started UrlShortenerApplication in 6.01 seconds (JVM running for 12.165)
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Step 2: 生成短鏈

$ curl -X POST http://127.0.0.1:8080/v1 \
  -H 'Content-Type: text/plain' \
  -d https://y0ngb1n.github.io
515bbe2b
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Step 3: 還原短鏈

$ curl -X GET http://127.0.0.1:8080/v1/515bbe2b
https://y0ngb1n.github.io
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檢視日誌

...
2019-08-21 21:42:26.788 DEBUG 10244 --- [nio-8080-exec-2] i.g.y.s.u.c.UrlShortenerController       : URL Id generated: 515bbe2b
2019-08-21 21:42:40.748 DEBUG 10244 --- [nio-8080-exec-3] i.g.y.s.u.c.UrlShortenerController       : URL Retrieved: https://y0ngb1n.github.io
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參考資料

• youtu.be/Zr0E2VP24w8
• en.wikipedia.org/wiki/Murmur…
• github.com/google/guav…
• www.flyml.net/2016/09/05/…
• 短網址（Short URL）系統的原理及其實現，by 胡方運
• 如何快速判斷某 URL 是否在一個 20 億的網址 URL 集合中？，by 張振偉
  • 應用場景：黑名單、URL 去重、單詞拼寫檢查、Key-Value 快取系統的 Key 校驗、ID 校驗，比如訂單系統查詢某個訂單 ID 是否存在，如果不存在就直接返回
• 談談全域性唯一 ID 生成方法
• Leaf — 美團點評分散式 ID 生成系統