问题描述
要在 Struts 2 中获取 servlet 请求，我们可以使用 ServletRequestAware 或 ServletActionContext.但是，在特定的 Internet 资源，它被告知应该使用ServletRequestAware 而不是ServletActionContext.
To get a servlet request in Struts 2 we can use either ServletRequestAware or ServletActionContext. However, in a particular internet resource, it is told that ServletRequestAware should be used instead of ServletActionContext.
这是否与 ServletActionContext 将成为多线程环境中的共享资源有关，或者这背后是否有任何其他原因?
Does that have something to do with the fact that ServletActionContext will be a shared resource in a multi-threaded environment or is there any other reason behind this?
推荐答案
ServletActionContext 是一个仅包含静态方法的辅助类，其中一个用于从动作上下文中检索 servlet 请求.但是操作上下文是 ThreadLocal，所以它不能在多线程环境中共享.
The ServletActionContext is a helper class that contains only static methods, one of them used to retrieve servlet request from action context.But action context is ThreadLocal, so it can't be shared in multi-threaded environment.
Struts2 中也没有每个请求的多线程环境，除了 executeAndWait 拦截器使用的后台线程.
There's also no multi-threded environment per request in Struts2, except a background thread used by the executeAndWait interceptor.
使用ServletRequestAware 的原因是因为如果servletConfig 拦截器包含在堆栈中，它是获得servlet 请求对象的保证方法.
The reason to use ServletRequestAware is because it's guaranteed method to obtain a servlet request object if servletConfig interceptor is included in the stack.
您可以在任何地方使用 ServletActionContext，但它不保证将返回请求对象而不是 null.
You can use ServletActionContext from anywhere, but it doesn't guarantee that a request object instead of null will be returned.
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