Local caching in Java caching technology

With the continuous development of Internet applications, the efficiency and performance of data access have become crucial factors. Caching technology has been widely used as a means to effectively improve data access efficiency. Among them, local caching, as a common form of caching technology, has also attracted more and more attention.

What is local cache?

Partial caching, as the name suggests, is to cache part of the data in an application system into local memory. The opposite is the global cache, which caches the entire system's data in memory, while the local cache only caches part of the data that needs to be accessed frequently.

Advantages of local cache

Compared with global cache, local cache has the following obvious advantages:

1. Reduce network overhead

Local caching only caches data that needs to be accessed frequently, reducing the number of system visits to the remote cache server, thereby reducing network overhead.

2. Improve system performance

Local cache can quickly respond to user requests because it only needs to read data from local memory without waiting for a response from the remote server , thereby improving application performance.

3. Improve data access efficiency

Local caching can cache data fields that require frequent access, reducing data access time and improving data access efficiency.

Specific implementation of local caching

In Java applications, partial caching can be easily implemented by using some frameworks or class libraries. The following are some of the more common implementations.

1. Using Map Collection

The Map collection in Java is a data structure used to store key-value pairs. We can use Map implementation classes such as HashMap or ConcurrentHashMap to implement local caching. For example, the following code snippet demonstrates how to use ConcurrentHashMap to implement a simple local cache:

private static ConcurrentHashMap<String, Object> cache = new ConcurrentHashMap<>();

public static Object get(String key) {
    return cache.get(key);
}

public static void put(String key, Object value) {
    cache.put(key, value);
}

2. Using the Guava library

Guava is a set of Java class libraries launched by Google . The Cache class can be used to implement local caching. For example, the following code snippet demonstrates how to use the Cache class to implement a local cache:

private static Cache<String, Object> cache = CacheBuilder.newBuilder()
        .maximumSize(1000)
        .expireAfterWrite(10, TimeUnit.MINUTES)
        .build();

public static Object get(String key) {
    return cache.getIfPresent(key);
}

public static void put(String key, Object value) {
    cache.put(key, value);
}

In the above code, CacheBuilder is a builder used to build Cache instances and sets the maximum size and expiration time of the cache. The getIfPresent method is used to obtain the value corresponding to a key in the cache, and returns null if it does not exist. The put method is used to add key-value pairs to the cache.

3. Using Redis cache

Redis is a high-performance cache server that supports multiple data structures and complex data operations. We can use the Java client of Redis to implement partial caching. For example, the following code snippet demonstrates how to implement a simple local cache through Jedis:

private static Jedis jedis = new Jedis("localhost");

public static Object get(String key) {
    String value = jedis.get(key);
    if (value == null) {
        return null;
    }
    return JSON.parseObject(value, Object.class);
}

public static void put(String key, Object value) {
    jedis.set(key, JSON.toJSONString(value));
    jedis.expire(key, 60);
}

In the above code, we use Jedis as the Java client of Redis, and obtain the corresponding key in the cache through the get method value, and use the JSON.parseObject method to convert the value to an Object object. The put method is used to add a key-value pair to the cache, and the expire method is used to set the expiration time of the key to 60 seconds.

Summary

Partial cache has obvious advantages in improving data access efficiency, improving system performance and reducing network overhead, and is widely used in practical applications. Through some frameworks or class libraries in Java, we can easily implement local caching to improve system performance and user experience.

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