java 在java中缓存方法的结果
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Caching the result of a method in java
提问by jmruc
I have this method that loads a lot of data from the database
我有这种从数据库加载大量数据的方法
private List<Something> loadFromDb() {
//some loading which can take a lot of time
}
I am looking for a simpleway to cache the results for some fixed time (2 minutes for example). I do not need to intercept the method invocation itself, just to cache the returned data- I can write another method that does the caching if necessary.
我正在寻找一种简单的方法来缓存某个固定时间（例如 2 分钟）的结果。我不需要拦截方法调用本身，只是为了缓存返回的数据- 如果需要，我可以编写另一个进行缓存的方法。
I don't want to:
我不想：
- Use AOP compile time weaving like this one- it requires changes in the build
- Use
@Cacheablein Spring - I have to define a cache for each cacheable method
- 像这样使用 AOP 编译时编织- 它需要在构建中进行更改
@Cacheable在 Spring 中使用- 我必须为每个可缓存的方法定义一个缓存
Is there a library which can simplify this task, or should I do something else? An example use of such library would be
是否有可以简化此任务的库，或者我应该做其他事情吗？使用此类库的示例是
private List<Something> loadFromDbCached() {
//in java 8 'this::loadFromDb' would be possible instead of a String
return SimpleCaching.cache(this, "loadFromDb", 2, MINUTES).call();
}
EDIT:I am looking for a library that does that, managing the cache is more trouble than it seems, especially if you have concurrent access
编辑：我正在寻找一个这样做的库，管理缓存比看起来更麻烦，特别是如果你有并发访问
回答by thSoft
Use Guava's Suppliers.memoizeWithExpiration(Supplier delegate, long duration, TimeUnit unit):
使用 Guava 的Suppliers.memoizeWithExpiration(Supplier delegate, long duration, TimeUnit unit)：
private final Supplier<List<Something>> cache =
Suppliers.memoizeWithExpiration(new Supplier<List<Something>>() {
public List<Something> get() {
return loadFromDb();
}
}, 2, MINUTES);
private List<Something> loadFromDbCached() {
return cache.get();
}
回答by Arnab Biswas
Check Guava Cache BuilderIt may be useful.
检查Guava Cache Builder可能有用。
回答by yegor256
You can use @Cacheableannotation from jcabi-aspects:
您可以使用jcabi-aspects 中的@Cacheable注释：
public class Resource {
@Cacheable(lifetime = 5, unit = TimeUnit.SECONDS)
public String load(URL url) {
return url.openConnection().getContent();
}
}
The result of load()will be cached for five seconds. Check this article, it explains the details: http://www.yegor256.com/2014/08/03/cacheable-java-annotation.html
的结果load()将被缓存五秒钟。检查这篇文章，它解释了详细信息：http: //www.yegor256.com/2014/08/03/cacheable-java-annotation.html
