Java Servlet池 [英] Java Servlet Pooling

问题描述

在Tomcat 6下的Servlets 101：

Servlets 101, under Tomcat 6:

有人可以指点我对例如最佳方式的一个很好的解释。在servlet启动时创建一个昂贵的Foo对象的集合，并将它们存放在我可以在处理每个请求时访问它们的地方？

Could someone kindly point me to a good explanation of the best way to eg. create a Collection of expensive Foo objects at servlet startup time and stash them somewhere where I can access them while processing each request?

我可以告诉至少有三个如何做到这一点，我在差异上有点模糊。我并不关心集群或算法来驱逐陈旧的条目或类似的东西，只是基础知识。

Near as I can tell there are at least three ways to do this and I am a bit fuzzy on the difference. I am not concerned with clustering or algorithms to evict stale entries or anything like that, just the basics.

干杯谢谢。

推荐答案

实现 ServletContextListener ，在 contextInitialized（）期间执行所需的加载任务，并将结果存储在应用范围由 ServletContext＃setAttribute（）组成。它将在服务器启动期间调用，并且应用程序范围也可以在常规servlet中访问。

Implement a ServletContextListener, do the desired loading task during contextInitialized() and store the result in the application scope by ServletContext#setAttribute(). It will be invoked during server's startup and the application scope is accessible inside regular servlets as well.

基本示例：

public class Config implements ServletContextListener {
   public void contextInitialized(ServletContextEvent event) {
        List<Foo> foos = fooDAO().list();
        event.getServletContext().setAttribute("foos", foos);
    }
}

将其映射到 web。 xml 通常的方式：

Map it in web.xml the usual way:

<listener>
    <listener-class>mypackage.Config</listener-class>
</listener>

以下是在常规servlet中访问它的方法：

Here's how to access it in regular servlets:

protected void doSomething(request, response) {
    List<Foo> foos = (List<Foo>) getServletContext().getAttribute("foos");
}

以下是在JSP中访问它的方法：

And here's how you can access it in JSPs:

<c:forEach items="${foos}" var="foo">
    ${foo.someProperty}<br>
</c:forEach>

这就是说，我真的不知道这与servlet pool有什么关系。这个词毫无意义。

That said, I really don't see how that is related to "servlet pool". This term makes no sense.

希望这会有所帮助。

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