如何在简单的类文件中获取ServletContext对象?

问题描述

我正在创建一个简单的Web应用程序.我需要在该类中获取对ServletContext对象的引用.我怎么能得到它?

I am creating a simple web application. I need to get reference to ServletContext object in that class. How can i get it?

推荐答案

最好将其作为参数传递给对象的构造函数，或使用setter方法进行设置.

You'd better pass it as argument to the constructor of your object, or set it using a setter method.

实际上，您可以获取与对象相关的context属性，并仅通过构造函数/setter传递它.例如:

In fact, you may obtain the context attribute that is relevant to your object and pass only it via constructor/setter. For example:

YourClass obj = 
    new YourClass((AnotherClass) servletContext.getAttribute("yourAttribute"));

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更糟糕，更复杂的选择是:

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A much worse and more complication option is to:

1. 创建一个 ServletContextListener
2. 使用< listener>< listener-class></listener-class></listener>
在web.xml中注册
3. 在 contextInitialized(..)上从事件中获取 ServletContext 并将其存储在单个实例中-某个静态字段.

1. Create a ServletContextListener
2. register it in web.xml with <listener><listener-class></listener-class></listener>
3. on contextInitialized(..) get the ServletContext from the event and store it in a singleton - a static field somehwere.

或者，您可以使用 ServletRequestListener 对每个请求执行此操作，并将其存储在 ThreadLocal 中.

Alternatively, you can do this on each request, using a ServletRequestListener and store it in a ThreadLocal instead.

然后您可以通过调用单例/threadlocal持有者来获取值，如下所示:

Then you can obtain the value via calling your singleton/threadlocal holder like this:

ServletContextHolder.getCurrentServletContext()

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