Get to know Google Guava caching technology

Google Guava is a Java tool library provided by Google to facilitate developers to use Java to develop efficient and high-quality applications. Caching technology is an important feature of Guava. Below we will introduce the characteristics, usage and precautions of Guava caching technology.

1. Features of Guava cache

The main features of Guava cache are as follows:

1. Multiple cache recycling strategies: Guava supports multiple cache recycling strategies , including based on size, time, or usage.
2. Cache data type support: Guava cache supports caching of multiple data types, such as primitive types, objects, collections, etc.
3. High performance: Guava cache has the characteristics of high performance, and the underlying implementation adopts a concurrent method.
4. Auto-loading: Guava cache supports automatic loading to avoid applications loading large amounts of data at startup.

2. How to use Guava cache

The following will introduce how to use Guava cache. First, you need to introduce the guava-xx.xx.jar package:

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.Cache;

Then use CacheBuilder to build the Cache object. The specific code is as follows:

Cache<String, String> cache = CacheBuilder.newBuilder().
    maximumSize(1000)
    .expireAfterWrite(10, TimeUnit.MINUTES)
    .build();

The maximumSize() method specifies the maximum capacity of the cache, expireAfterWrite( ) method specifies the cache expiration time. In addition, cache eviction policies can be used to control cache size and stateful management.

Next, you can add data to the cache through the put() method of Cache, and obtain the data in the cache through the get() method. The specific code is as follows:

cache.put("key1", "value1");
String value = cache.get("key1", new Callable < String > () {
    @Override
    public String call() {
        //从数据库或其他数据源加载数据
        return "newValue";
    }
});

In the above code, the first One parameter is the cached key value, and the second parameter is the default value/Callback object. When the specified key cannot be found, the data is loaded from the logic provided in the default value and the loaded data is updated to the cache. middle.

3. Precautions for Guava cache

When using Guava cache, you need to pay attention to the following points:

1. To avoid memory overflow: when setting the cache capacity, The amount of data in actual application scenarios must be taken into consideration to avoid memory overflow.
2. Choose an appropriate cache recycling strategy: Choose an appropriate cache recycling strategy based on actual usage to minimize data redundancy in the cache.
3. Avoid the objective validity period of the cache being too long: Too long a validity period will cause the cached data to become outdated and not meet actual business needs.

4. Conclusion

Through the introduction of this article, we can understand the characteristics, usage and precautions of Guava caching technology. In practical applications, the reasonable application of caching technology can not only improve the performance and efficiency of applications, but also reduce access to back-end data sources, avoid impact on system performance, and improve system availability and maintainability.

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