Research on the technical principle of the core cache framework based on the Java class library
Research on the technical principle of the core cache framework based on the Java class library
Abstract: The cache framework is one of the key technologies to improve system performance and response speed.This article will introduce the core cache framework technical principles based on the Java class library and provide relevant Java code examples.
1 Introduction
With the development of computer technology, system performance and response speed have become increasingly important.As a key technology, the cache framework can effectively improve the performance and response speed of the system.As a widely used programming language, Java provides many class libraries and tools that can be used to build cache framework.This article will explore the technical principles of the core cache framework based on the Java class library.
2. The basic principle of cache
Ccheca is a technology that keeps calculation results or data in memory to quickly access.The basic principle of cache is to use the local principle of time and space.When a data item is accessed, its neighboring data items are likely to be accessed.Therefore, stored the recent data in the cache can reduce the number of access to the rear -end storage system, thereby increasing access speed.
3. The core cache framework in the Java library
Several core classes and interfaces in the Java library can be used to build cache framework.The following are some of the main categories:
-java.util.hashmap: HashMap is one of the most basic cache data structures in Java.HashMap can be used to store key values on data and quickly find the corresponding value according to the key.However, HashMap did not provide an automatic expiration and elimination mechanism.
-java.util.weakhashmap: Weakhashmap inherits from HashMap, but it uses weak reference to save the key.When the key has no strong reference, the garbage recovery can be recycled at appropriate.In this way, when the system memory is insufficient, the garbage recyrior will automatically remove the cache items that are no longer used.
-java.util.linkedhashmap: Linkedhashmap is a subclass of HashMap. It uses a two -way linked list to maintain the order of the element.In addition to the fast search ability of HashMap, Linkedhashmap also provides the ability to access the order in accordance with the element access order (the recently visited elements), which is very useful for building a cache framework.
In addition to the above categories, the Java class library also provides mature cache frameworks and tools such as ConcurrenThashMap, EHCACHE, and Guava Cache. They have more advanced functions, such as concurrency, expiration strategies, elimination strategies, etc.
4. Example code
Below is a sample code for building a cache framework using LinkedhashMap in the Java library:
import java.util.LinkedHashMap;
import java.util.Map;
public class Cache<K, V> extends LinkedHashMap<K, V> {
private final int maxSize;
public Cache(int maxSize) {
super(maxSize + 1, 1.0f, true);
this.maxSize = maxSize;
}
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > maxSize;
}
public static void main(String[] args) {
Cache<Integer, String> cache = new Cache<>(5);
cache.put(1, "A");
cache.put(2, "B");
cache.put(3, "C");
cache.put(4, "D");
cache.put(5, "E");
System.out.println(cache); // Output: {1=A, 2=B, 3=C, 4=D, 5=E}
cache.put(6, "F");
System.out.println(cache); // Output: {2=B, 3=C, 4=D, 5=E, 6=F}
}
}
The above example code shows a cache framework based on Linkedhashmap.We can limit the number of cache items by setting the maximum cache size.When the number of cache exceeds the maximum cache size, the earliest cache items that are added will be removed.
in conclusion
This article introduces the technical principles of the core cache framework based on the Java class library.We understand the basic principles of cache and introduce the cache class commonly used in the Java library.Through the example code, we show how to use Linkedhashmap in the Java class library to build a simple cache framework.It is hoped that this article can know readers about the core cache framework technology based on the Java class library.
