How do i get ServletContext object in a simple class file?

Question

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

Answer 1

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

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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A much worse and more complication option is to:

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.

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

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

ServletContextHolder.getCurrentServletContext()

Answer 2

我有这个问题，但是因为我从JSP调用了类，所以我只是将JSP中的HttpServletRequest“request”引用传递给了类，并在类中调用了：

String appPath = request.getServletContext().getRealPath("");