Redis缓存数据库表(列单独缓存)的示例代码

<dependencies>  
    <!-- 其他依赖... -->  
    <dependency>  
        <groupId>redis.clients</groupId>  
        <artifactId>jedis</artifactId>  
        <version>3.7.0</version> 
    </dependency>  
</dependencies>

import redis.clients.jedis.Jedis;  
// 数据库中的User表对应的Java类  
class User {  
    private int id;  
    private String username;  
    private String email;  
    // 构造器、getter和setter方法...  
}  
// Redis操作类  
class RedisCache {  
    private Jedis jedis;  
    public RedisCache(String host, int port) {  
        jedis = new Jedis(host, port);  
    }  
    // 缓存User数据  
    public void cacheUser(User user) {  
        String userIdKey = "user:id:" + user.getId();  
        String usernameKey = "user:username:" + user.getId();  
        jedis.set(userIdKey, String.valueOf(user.getId()));  
        jedis.set(usernameKey, user.getUsername());  
    }  
    // 根据ID获取缓存中的User数据  
    public User getUserById(int id) {  
        String userIdKey = "user:id:" + id;  
        String usernameKey = "user:username:" + id;  
        String userId = jedis.get(userIdKey);  
        String username = jedis.get(usernameKey);  
        if (userId != null && username != null) {  
            User user = new User();  
            user.setId(Integer.parseInt(userId));  
            user.setUsername(username);  
            // 注意：这里我们没有缓存email，所以需要从数据库获取或设为null  
            // 根据实际需求，你也可以选择缓存email或其他字段  
            return user;  
        }  
        return null;  
    }  
    // 关闭连接  
    public void close() {  
        if (jedis != null) {  
            jedis.close();  
        }  
    }  
}  
// 主类，用于演示如何使用RedisCache  
public class RedisCacheExample {  
    public static void main(String[] args) {  
        RedisCache redisCache = new RedisCache("localhost", 6379);  
        // 假设这是从数据库获取的User对象  
        User userFromDatabase = new User();  
        userFromDatabase.setId(1);  
        userFromDatabase.setUsername("john_doe");  
        userFromDatabase.setEmail("john.doe@example.com");  
        // 将User对象缓存到Redis中  
        redisCache.cacheUser(userFromDatabase);  
        // 从Redis中根据ID获取User对象  
        User cachedUser = redisCache.getUserById(1);  
        if (cachedUser != null) {  
            System.out.println("Cached User ID: " + cachedUser.getId());  
            System.out.println("Cached Username: " + cachedUser.getUsername());  
        } else {  
            System.out.println("User not found in cache");  
        }  
        // 关闭Redis连接  
        redisCache.close();  
    }  
}