加快Tomcat应用程序响应速度的方法：使用缓存技术

<dependency>
    <groupId>org.ehcache</groupId>
    <artifactId>ehcache</artifactId>
    <version>3.9.0</version>
</dependency>

<ehcache>
    <cache name="userCache" maxEntriesLocalHeap="1000" eternal="false" timeToLiveSeconds="3600" />
</ehcache>

import org.ehcache.Cache;
import org.ehcache.CacheManager;
import org.ehcache.config.CacheConfiguration;
import org.ehcache.config.builders.CacheConfigurationBuilder;
import org.ehcache.config.builders.CacheManagerBuilder;

public class UserService {
    private static final CacheManager CACHE_MANAGER = CacheManagerBuilder.newCacheManagerBuilder()
            .withCache("userCache", CacheConfigurationBuilder.newCacheConfigurationBuilder(Long.class, User.class)
                    .build())
            .build(true);

    public User getUserById(Long id) {
        Cache<Long, User> userCache = CACHE_MANAGER.getCache("userCache", Long.class, User.class);
        User user = userCache.get(id);
        if (user == null) {
            // 从数据库获取数据，并将数据放入缓存
            user = userDao.getUserById(id);
            userCache.put(id, user);
        }
        return user;
    }
}