The technical principle analysis of the technical principles of the "Disk Lru Cache" framework in the Java class library

DISK LRU Cache (Disk LRU cache) is a cache framework commonly used in the Java library. It provides efficient data access and storage functions by cache data to the disk.This article will analyze the technical principles of the Disk Lru Cache framework and provide relevant programming code examples and configuration descriptions. 1. Technical principles 1.1 Cache principle Disk Lru Cache uses the LRU (recently used) algorithm to manage the cache.The LRU algorithm eliminates less access from the cache according to the sequence of data access, so that the data in the cache is more popular data and improves the efficiency of data access. 1.2 cache data structure Disk Lru Cache uses a two -way linked list and a hash table to organize caching data.The two -way linked list maintains the order of data access. The recent access data will be moved to the head of the linked list, and the data that has not been accessed for a long time will be moved to the tail of the linked list.The hash table establishes a mapping relationship with the key value pair in the form of key value pair. 1.3 Disk storage principle In order to store data on the disk, the Disk Lru Cache uses a separate storage method.Each data block is stored in an independent file, and the file name uses the data block key to name.When you need to read the data, find the corresponding file in the hash table through the key value and read the corresponding data from the file. 1.4 cache strategy Disk Lru Cache controls the cache size and strategy through some configuration parameters.For example, the maximum capacity of cache can be set. When the capacity limit is exceeded, the latest data used at the least recently used can be eliminated.You can also set the maximum size of each data block in the cache. When the size limit is exceeded, the data block is divided into multiple files for storage, and the data is divided into appropriate data. 2. Programming code example Below is a simple sample code using the Disk Lru Cache framework: // Import related class libraries import com.jakewharton.disklrucache.DiskLruCache; // Initialize cache DiskLruCache cache = DiskLruCache.open(cacheDir, appVersion, valueCount, maxSize); // Storing data String key = "exampleKey"; String value = "exampleValue"; DiskLruCache.Editor editor = cache.edit(key); editor.set(0, value); editor.commit(); // Read the data DiskLruCache.Snapshot snapshot = cache.get(key); String retrievedValue = snapshot.getString(0); snapshot.close(); // Empty the cache cache.delete(); cache.close(); 3. Related configuration description When using Disk Lru Cache, you can configure some parameters to meet specific needs. 3.1 cache directory When initializing the cache, a directory of storing the cache file needs to be specified.You can use the `GetCacheDir () method to obtain the application of the application, or manually specify the path through the` new file ("path/to/cache/dir") `). 3.2 Application version number When initialized cache, a application version number needs to be provided.It can usually be obtained through the `getpackagemanager (). GetPackageInfo (getpackageName (), 0) .VersionCode`. 3.3 Number of data blocks When initializing the cache, the number of data blocks (files) in the cache needs to be specified.Usually, it can be set to 1. 3.4 cache maximum capacity When initializing the cache, the maximum capacity of the cache can be set, and the unit is byte.For example, it can be set to 10MB: `10 * 1024 * 1024`. Through the above configuration parameters, you can use the Disk Lru Cache framework according to specific needs to achieve efficient data storage and access functions. In summary, the Disk Lru Cache framework uses the LRU algorithm and disk storage principle to achieve efficient data cache function.By using related programming code and configuration parameters, you can easily integrate and use the framework in the Java class library.