The advantages and application scenarios of the LRU cache frame in the Java library
The advantages and application scenarios of the LRU cache frame in the Java library
Overview:
LRU (Least Recently Used) is the most recent abbreviation.It is a common cache replacement strategy, indicating that when the cache capacity reaches the upper limit, the longest unused cache object is replaced.In the Java library, the LRU cache framework provides developers with efficient cache management tools that can greatly improve the performance and response time of the program.
Advantage:
1. Improve performance: The LRU cache framework can improve the performance of the program because it uses the most frequent cache object and keep it in memory, thereby reducing the number of disk read and writing operations.In this way, the execution speed of the program has been significantly improved.
2. Cache size controlled: LRU cache frame allows developers to set up the maximum capacity of the cache. When the cache reaches the capacity limit, the most unused objects that are not used will be automatically deleted to freeze the space.This can avoid cache excessive and consume too much memory resources.
3. Simple and easy to use: The Java class library provides many excellent LRU cache frameworks. They usually have simple and clear APIs, which are easy to use and integrate into projects.
Application scenario:
1. Database query results cache: In high concurrent database queries, use the LRU cache framework to cache query results to avoid excessive database reading operations and improve query response speed.
2. Network request cache: In network requests, there are often a large number of the same or similar requests.Use the LRU cache framework to cache the results of the network request. When the same request is initiated again, the result is obtained directly from the cache, reducing network delays and reducing the server load.
3. Picture loading cache: In Android development, a large amount of picture resources are often required.The use of the LRU cache frame can effectively manage the loaded picture resources. When the picture is no longer displayed or the memory is insufficient, it replaces it to reduce memory occupation and loading time.
Example code:
Below is a simple Java code example, using LinkedhashMap to implement the LRU cache framework.
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
private final int capacity;
public LRUCache(int capacity) {
super(capacity + 1, 1.1f, true);
this.capacity = capacity;
}
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > capacity;
}
public static void main(String[] args) {
LRUCache<String, Integer> cache = new LRUCache<>(3);
cache.put("a", 1);
cache.put("b", 2);
cache.put("c", 3);
cache.get("b");
cache.put("d", 4);
System.out.println (cache); // Output: {b = 2, c = 3, d = 4}
}
}
The above code defines a LRUCACHE class, inherited from LinkedhashMap, and rewritten the RemovelDestentry method to control the cache capacity.In the main method, first create a Lrucache object with a capacity of 3, and then insert 4 key values pairs, and finally output the current cache content.Because there are only 3 capacity, when the cache is full, the key value pair of the longest unused will be replaced.
Summarize:
The LRU cache framework has many advantages in the Java library, and it is suitable for many scenarios, such as the cache of the database query results, the cache of the network request cache, and the picture loading cache.Developers can choose the suitable LRU cache framework according to specific needs, and integrate and use it through simple code examples.By using the LRU cache framework reasonably, the performance and response time of the program can be significantly improved.
