How to use the LRU cache framework in the Java library to improve performance
How to use the LRU cache framework in the Java library to improve performance
Overview:
In computer science and software engineering, cache is a technology for temporary storage data that can improve the performance of the application.LRU (recently used) is a common cache replacement strategy, and the recent minimum data items will be eliminated first.In the Java class library, many open source libraries that have achieved the LRU cache framework have been implemented. This article will introduce how to use these frameworks to improve the performance of the application.
Step 1: Import the LRU cache framework
There are some mature open source LRU cache frames in the Java class library, such as Guava Cache, Caffeine, and EHCACHE.First, you need to choose a suitable framework according to your needs and import them into your project.You can add corresponding dependencies to building tools such as Maven or Gradle, or you can download and manually import it from the official website of the framework.
Step 2: Configure the cache framework
Configure the cache frame is an important step to use the LRU cache.Different frameworks may have different configuration methods. The following uses Guava Cache as an example.First, you need to create a Cache object and specify its capacity limit.The following code fragment shows how to use Guava Cache to create a LRU cache with a maximum capacity of 100:
Cache<String, Object> cache = CacheBuilder.newBuilder()
.maximumSize(100)
.build();
Through the Maximsize () method, you can specify the maximum capacity of the cache, that is, the maximum number of data items that can be stored in the cache.When the cache capacity reaches the maximum limit, the recently used data items will be automatically eliminated.
Step 3: Use the cache framework
Once the configuration is completed, the cache framework can be used to improve the performance of the application.Here are several common cases that use the LRU cache framework:
a) Calculation results:
Suppose you have a time -consuming calculation function, you can use the cache framework to cache the calculation results to avoid repeated calculations.The following is an example code that uses Guava Cache to implement this function:
Cache<String, Integer> cache = CacheBuilder.newBuilder()
.maximumSize(100)
.build();
public int calculateValue(String key) {
int result;
if (cache.getIfPresent(key) != null) {
result = cache.getIfPresent(key);
} else {
result = // Calculate the time -consuming calculation
cache.put(key, result);
}
return result;
}
b) The results of the cache database query:
If your application frequently executes the database query, you can use the LRU cache framework to cache query results to reduce access to the database.The following is an example code that uses the cache frame buffer database to query the results:
Cache<Long, List<User>> cache = Caffeine.newBuilder()
.maximumSize(100)
.build();
public List<User> getUsersFromDatabase(Long groupId) {
List<User> result;
if (cache.getIfPresent(groupId) != null) {
result = cache.getIfPresent(groupId);
} else {
result = // Inquiry the user from the database
cache.put(groupId, result);
}
return result;
}
c) Calling external API call results:
When the external API is called, the response time may be longer.To improve the performance of the application, you can use the LRU cache framework to cache the response results of the external API.The following is an example code that uses the EHCACHE cache frame to cache the external API call:
Cache<String, ApiResponse> cache = EhcacheBuilder.newBuilder()
.maximumSize(100)
.build();
public ApiResponse callExternalApi(String url) {
ApiResponse result;
if (cache.get(url) != null) {
result = cache.get(url);
} else {
Result = // Call the external API and get a response
cache.put(url, result);
}
return result;
}
in conclusion:
By using the LRU cache framework in the Java library, you can effectively improve the performance of the application.In this article, we introduced how to import the LRU cache frame, configuration cache frame, and several common cases of using the cache frame.Of course, according to your specific needs, you may need to configure and use more detailed configuration and use according to the documents and examples of the framework.However, no matter which framework you use, the LRU cache provides you with a simple and effective cache strategy to improve the performance of the application.
