The implementation principle of cache management in the Javaee API framework
The cache management in the Javaee API aims to improve the performance and scalability of the application, and reduce access to the persistent storage system by storing the frequently accessible data in memory.This article will introduce the implementation principles of cache management in Javaee and provide some Java code examples.
In Javaee, there are two common cache management implementation methods: local cache based on the Java set framework and a distributed cache based on a third -party cache library.
1. Local cache based on the Java collection framework
Local cache is stored in the memory of the application, and usually uses HashMap or ConcurrenThashMap to achieve.The following is a simple example. Demonstration of how to use ConcurrenThashMap to achieve local cache:
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class LocalCacheManager {
private Map<String, Object> cache;
public LocalCacheManager() {
cache = new ConcurrentHashMap<>();
}
public void put(String key, Object value) {
cache.put(key, value);
}
public Object get(String key) {
return cache.get(key);
}
public void remove(String key) {
cache.remove(key);
}
}
The advantage of using the local cache is fast, and the reading and writing operations are performed in memory, which is suitable for a single -machine environment or a small amount of data.However, because the data is stored in the memory of the application, restarting the server or application will cause data loss and not suitable for scenarios that require persistence data.
2. Distributed cache based on the third -party cache library
The distributed cache is to store data in a distributed cache server and access the cache through the network.Common third -party cache libraries include Redis, Memcached, etc.The following is an example of using Redis as a distributed cache:
import redis.clients.jedis.Jedis;
public class DistributedCacheManager {
private Jedis jedis;
public DistributedCacheManager() {
jedis = new Jedis("localhost", 6379);
}
public void put(String key, String value) {
jedis.set(key, value);
}
public String get(String key) {
return jedis.get(key);
}
public void remove(String key) {
jedis.del(key);
}
}
The advantage of using a third -party cache library is that the data can be stored in an independent cache server, which is suitable for the multi -server environment or large data volume.The cache server usually provides the characteristics of persistence and high availability, and data is not easy to lose.
When using cache management, the following points need to be considered:
1. Cache strategy: Select the appropriate cache strategy according to the access frequency and importance of data, such as LRU (recently using at least algorithms), LFU (at least used algorithms), etc.
2. Cache failure mechanism: In order to maintain the timeliness of the data, the cache failure mechanism needs to be achieved.It can be checked with timing tasks or timestamps. When the data expires, it needs to be retracted from the database or other persistent storage.
3. Cache update: When the data changes, it is important to ensure the consistency of cache.You can update the cache at the same time when the data is updated, or notify other servers to refresh the cache with the release-subscription mode.
Summarize:
The cache management in Javaee improves the performance and scalability of the application through two ways: local cache and distributed cache.Local cache is used to store data in the memory of the application, which is suitable for a single -machine environment and a small amount of data.The distributed cache is used to store data in an independent cache server, which is suitable for multi -server environment and large data volume.When using caching management, it is necessary to consider factors such as cache strategy, cache failure mechanism, and cache update to ensure the consistency and timelyness of the data.
