初始化参数和上下文参数 [英] init-param and context-param
问题描述
和
有什么区别!?
What is the difference between <init-param>
and <context-param>
!?
推荐答案
和
是静态参数,它们被存储在 web.xml 文件中.如果您有任何不经常更改的数据,您可以将其存储在其中之一中.
<init-param>
and <context-param>
are static parameters which are stored in web.xml file. If you have any data which doesn't change frequently you can store it in one of them.
如果您想存储限于特定 servlet 范围的特定数据,那么您可以使用 <init-param>
.您在 <init-param>
只能被那个特定的 servlet 访问.init-param 在 <servlet>
标签内声明.>
If you want to store particular data which is confined to a particular servlet scope, then you can use <init-param>
.Anything you declare inside <init-param>
is only accessible only for that particular servlet.The init-param is declared inside the <servlet>
tag.
<servlet>
<display-name>HelloWorldServlet</display-name>
<servlet-name>HelloWorldServlet</servlet-name>
<init-param>
<param-name>Greetings</param-name>
<param-value>Hello</param-value>
</init-param>
</servlet>
您可以按如下方式访问 servlet 中的这些参数:
and you can access those parameters in the servlet as follows:
out.println(getInitParameter("Greetings"));
如果您想存储整个应用程序通用的数据,并且如果它不经常更改,则可以使用
而不是 >servletContext.setAttribute()
应用程序上下文的方法.有关
VS ServletContext.setAttribute()
用法的更多信息,请查看此 问题.context-param 在标签 web-app
下声明.您可以按如下方式声明和访问
If you want to store data which is common for whole application and if it doesn't change frequently you can use <context-param>
instead of servletContext.setAttribute()
method of the application context. For more information regarding usage of <context-param>
VS ServletContext.setAttribute()
have a look at this question. context-param are declared under the tag web-app
.
You can declare and access the <context-param>
as follows
<web-app>
<context-param>
<param-name>Country</param-name>
<param-value>India</param-value>
</context-param>
<context-param>
<param-name>Age</param-name>
<param-value>24</param-value>
</context-param>
</web-app>
在 JSP 或 Servlet 中的应用程序中的使用
Usage in the application either in a JSP or Servlet
getServletContext().getInitParameter("Country");
getServletContext().getInitParameter("Age");
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