Scala Web ::懒惰的Val范围/寿命 [英] Scala web :: lazy val scope/lifetime

问题描述

在Scala Web应用程序中，惰性val的作用域是应用程序服务器的生存期，还是请求的作用域?

In a Scala web application, is lazy val scoped to the lifetime of the application server, or request scoped?

我认为这是针对每个请求的，但无法找到确定的答案，因此就是问题.

I assume it is per request, but have not been able to find a definitive answer, thus the question.

谢谢

推荐答案

lazy是Scala功能，与Web应用程序编程无关.这意味着:在首次访问时仅评估一次.如果变量是每个请求创建的对象的一部分，则每个请求将对其进行一次惰性计算.

lazy is a Scala feature, not related to web application programming. It means: evaluate only once on first access. If the variable is part of an object created per request, it will be lazily evaluated once per every request.

如果在应用程序范围的类(或object)中声明了它，则一旦对其进行评估，它将在加载该类时保持其值不变(因此可能是WAR生存期).

If it is declared inside application-wide class (or object), once evaluated it will keep its value as long as the class is loaded (so probably the WAR lifetime).

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