feat: add redis-hash-shorten-url.md

利用 Redis Hash 实现短网址服务

Author: yanglbme

README.md

@@ -30,10 +30,11 @@
 ### 3. [Set 集合](/docs/redis-set-introduction.md)
 
 ### 4. [Sorted Sets 有序集合](/docs/redis-sorted-set-introduction.md)
-- [社交网站经常会有粉丝关注的功能，用 Redis 怎么实现？](/docs/redis-sorted-set-sns-follow.md)
+- [社交网站通常会有粉丝关注的功能，用 Redis 怎么实现？](/docs/redis-sorted-set-sns-follow.md)
 
 ### 5. [Hash 哈希](/docs/redis-hash-introduction.md)
 - [登录会话，用 Redis 该怎么做？](/docs/redis-hash-session-token.md)
+- [如何使用 Redis 实现短网址服务？](/docs/redis-hash-shorten-url.md)
 
 ### 6. [HyperLogLog](/docs/redis-hyperLogLog-introduction.md)
 

docs/redis-hash-shorten-url.md

@@ -0,0 +1,128 @@
+# 利用 Redis 哈希实现短网址
+
+## 代码实现
+| [Python](#Python-版本) | [Java](#Java-版本) |
+|---|---|
+
+### Python 版本
+```python
+from redis import Redis
+
+
+# 10进制数转换为36进制字符串
+def base10_to_base36(number: int) -> str:
+    alphabets = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+    result = ''
+    while number != 0:
+        number, i = divmod(number, 36)
+        result = alphabets[i] + result
+
+    return result or alphabets[0]
+
+
+URL_HASH_SHORT_SOURCE_KEY = 'url_hash:short_source'
+ID_COUNTER = 'short_url:id_counter'
+
+
+class URLShorten:
+
+    def __init__(self, client: Redis):
+        self.client = client
+        # 设置初始ID值，保留1-5位的短码，从6位的短码开始生成
+        self.client.set(ID_COUNTER, 36 ** 5 - 1)
+
+    def shorten(self, source_url: str) -> str:
+        """对源网址进行缩短，返回短网址ID"""
+        new_id = self.client.incr(ID_COUNTER)
+        short_id = base10_to_base36(new_id)
+        self.client.hset(URL_HASH_SHORT_SOURCE_KEY, short_id, source_url)
+        return short_id
+
+    def restore(self, short_id: str) -> str:
+        """根据短网址ID，返回对应的源网址"""
+        return self.client.hget(URL_HASH_SHORT_SOURCE_KEY, short_id)
+
+
+if __name__ == '__main__':
+    redis = Redis(decode_responses=True)
+    url_shorten = URLShorten(redis)
+
+    short_id = url_shorten.shorten('https://github.com/yanglbme')
+    print(short_id)  # 100000
+    source_url = url_shorten.restore(short_id)
+    print(source_url)  # https://github.com/yanglbme
+
+    print(url_shorten.shorten('https://doocs.github.io'))  # 100001
+```
+
+### Java 版本
+```java
+import redis.clients.jedis.Jedis;
+
+public class URLShorten {
+    private Jedis client;
+
+    private final String URL_HASH_SHORT_SOURCE_KEY = "url_hash:short_source";
+    private final String ID_COUNTER = "short_url:id_counter";
+
+    /**
+     * 将10进制数转换为36进制字符串
+     *
+     * @param number 10进制数
+     * @return 36进制字符串
+     */
+    private String base10ToBase36(long number) {
+        String alphabets = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        char[] chars = alphabets.toCharArray();
+        StringBuilder result = new StringBuilder();
+        while (number != 0) {
+            int i = (int) number % 36;
+            number /= 36;
+            result.insert(0, chars[i]);
+        }
+        return result.toString();
+    }
+
+    public URLShorten(Jedis client) {
+        this.client = client;
+        // 设置初始ID值，保留1-5位的短码，从6位的短码开始生成
+        this.client.set(ID_COUNTER, String.valueOf((long) Math.pow(36, 5) - 1));
+    }
+
+    /**
+     * 对源网址进行缩短，返回短网址ID
+     *
+     * @param sourceUrl 源网址
+     * @return 短网址ID
+     */
+    public String shorten(String sourceUrl) {
+        long newId = client.incr(ID_COUNTER);
+        String shortId = base10ToBase36(newId);
+        client.hset(URL_HASH_SHORT_SOURCE_KEY, shortId, sourceUrl);
+        return shortId;
+    }
+
+    /**
+     * 根据短网址ID，返回对应的源网址
+     *
+     * @param shortId 短网址ID
+     * @return 源网址
+     */
+    public String restore(String shortId) {
+        return client.hget(URL_HASH_SHORT_SOURCE_KEY, shortId);
+    }
+
+    public static void main(String[] args) {
+        Jedis client = new Jedis();
+        URLShorten urlShorten = new URLShorten(client);
+
+        String shortId = urlShorten.shorten("https://github.com/yanglbme");
+        System.out.println(shortId); // 100000
+        String sourceUrl = urlShorten.restore(shortId);
+        System.out.println(sourceUrl); // https://github.com/yanglbme
+
+        System.out.println(urlShorten.shorten("https://doocs.github.io")); // 100001
+
+    }
+}
+```