Application of Disk Lru Cache in the Java Class Library in disk storage
Application of Disk Lru Cache in the Java Class Library in disk storage
introduction:
In computer science, cache is a commonly used optimization technology to improve the efficiency of data access.Under normal circumstances, the cache is to store data in a faster storage system so that it can be accessed quickly when needed.However, in some scenarios, the data needs to be stored on the disk to process a large amount of data or long -lasting demand.Disk Lru Cache in the Java class library provides a cache implementation method based on disk storage.
What is Disk Lru Cache?
Disk Lru Cache is a cache solution that stored data on the disk. It manages the storage and access of data based on the recent minimum (LRU) strategy.It can storage data on the disk for the effect of cache and retrieve data effectively when runtime of the application.
The working principle of Disk Lru Cache:
DISK LRU Cache divides the data into multiple fixed -sized blocks, each block contains a key (key) and a value.These blocks are stored on the disk and can be loaded into memory as needed for reading and writing.DISK LRU Cache uses a two -way linked list to maintain the access order of the block. The block that recently visited is located at the head of the linked list. The minimum access to the linked list recently is located at the tail of the linked list.
When the application needs to access the data, Disk Lru Cache first searches the corresponding block in memory.If you find this block, you can return the data immediately when you find the block.Otherwise, you need to load the block from the disk to the memory and add it to the head of the linked list.If the memory space is insufficient, the Disk Lru Cache will remove the minimum closer from the tail of the linked list and write it back to the disk.This can ensure that the data in the memory is always the most commonly accessible data, and effectively improves the speed of data access.
Disk Lru Cache's Java code example:
The following is a simple Java code example using Disk Lru Cache:
import com.jakewharton.disklrucache.DiskLruCache;
import java.io.File;
import java.io.IOException;
public class DiskCacheExample {
private static final int APP_VERSION = 1;
private static final int VALUE_COUNT = 1;
private static final long CACHE_SIZE = 10 * 1024 * 1024; // 10MB
public static void main(String[] args) {
try {
File cacheDir = new File("path_to_cache_directory");
DiskLruCache cache = DiskLruCache.open(cacheDir, APP_VERSION, VALUE_COUNT, CACHE_SIZE);
// Write the data to the cache
String key = "example_key";
DiskLruCache.Editor editor = cache.edit(key);
if (editor != null) {
editor.set(0, "example_value");
editor.commit();
}
// Read data from the cache
DiskLruCache.Snapshot snapshot = cache.get(key);
if (snapshot != null) {
String value = snapshot.getString(0);
System.out.println("Cache value: " + value);
}
// Close the cache
cache.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we first created a Disklrucache object, specifying the cache directory, application version number, the number of values of each block, and cache size.We then use the edit () method to obtain an Editor object and write data to the cache through the object.Finally, we use the get () method to obtain a Snapshot object and read data from it.
in conclusion:
DISK LRU Cache is a cache solution used in Disk Storage in the Java class library. It manages the storage and access of data according to the LRU strategy.By storing data on a disk, Disk Lru Cache can effectively manage a large amount of data and increase the speed of data access.The above Java code example demonstrates how to use Disk Lru Cache for disk cache operation.
