Java 如何在简单的类文件中获取 ServletContext 对象？
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How do i get ServletContext object in a simple class file?
提问by TCM
I am creating a simple web application. I need to get reference to ServletContext object in that class. How can i get it?
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。我怎么才能得到它？
采纳答案by Bozho
You'd better pass it as argument to the constructor of your object, or set it using a setter method.
您最好将它作为参数传递给对象的构造函数，或者使用 setter 方法设置它。
In fact, you may obtain the context attribute that is relevant to your object and pass only it via constructor/setter. For example:
事实上，您可以获得与您的对象相关的上下文属性，并仅通过构造函数/setter 传递它。例如：
YourClass obj =
new YourClass((AnotherClass) servletContext.getAttribute("yourAttribute"));
A much worse and more complication option is to:
一个更糟糕、更复杂的选择是：
- Create a
ServletContextListener - register it in web.xml with
<listener><listener-class></listener-class></listener> - on
contextInitialized(..)get theServletContextfrom the event and store it in a singleton - a static field somehwere.
- 创建一个
ServletContextListener - 在 web.xml 中注册它
<listener><listener-class></listener-class></listener> - 在
contextInitialized(..)得到ServletContext从事件并将其存储在一个单-静态字段somehwere。
Alternatively, you can do this on each request, using a ServletRequestListenerand store it in a ThreadLocalinstead.
或者，您可以对每个请求执行此操作，使用 aServletRequestListener并将其存储在 a 中ThreadLocal。
Then you can obtain the value via calling your singleton/threadlocal holder like this:
然后你可以通过像这样调用你的单例/线程本地持有者来获取值：
ServletContextHolder.getCurrentServletContext()
回答by Ted Cahall
I had this issue, but since I had called the class from a JSP, I simply passed the HttpServletRequest "request" reference from the JSP to the class and made the call in the class to:
我遇到了这个问题，但是由于我从 JSP 调用了该类，所以我只是将 HttpServletRequest “请求”引用从 JSP 传递给了该类，并在该类中进行了调用：
String appPath = request.getServletContext().getRealPath("");
