web.xml配备参数context-param和init-param的区别

<context-param>   
           <param-name>context/param</param-name>   
           <param-value>avalible during application</param-value>   
</context-param>

?
(2)servlet范围内的参数，只能在servlet的init()方法中取得，在web.xml中配置如下：

?

<servlet>   
    <servlet-name>MainServlet</servlet-name>   
    <servlet-class>com.wes.controller.MainServlet</servlet-class>   
    <init-param>   
       <param-name>param1</param-name>   
       <param-value>avalible in servlet init()</param-value>   
    </init-param>   
    <load-on-startup>0</load-on-startup>   
</servlet> 

?在servlet中可以通过代码分别取用：

Java代码 ?

1. package?com.wes.controller;???? ??
2. ??? ??
3. import?javax.servlet.ServletException;???? ??
4. import?javax.servlet.http.HttpServlet;???? ??
5. ??? ??
6. public?class?MainServlet?extends?HttpServlet{???? ??
7. ??? ??
8. ????public?MainServlet(){???? ??
9. ????????super();???? ??
10. ??????}???? ??
11. ????public?void?init()?throws?ServletException?...{???? ??
12. ??????????System.out.println("下面的两个参数param1是在servlet中存放的");???? ??
13. ??????????System.out.println(this.getInitParameter("param1"));???? ??
14. ??????????System.out.println("下面的参数是存放在servletcontext中的");???? ??
15. ??????????System.out.println(getServletContext().getInitParameter("context/param"));???? ??
16. ???????}???? ??
17. }??

package com.wes.controller;    
   
import javax.servlet.ServletException;    
import javax.servlet.http.HttpServlet;    
   
public class MainServlet extends HttpServlet{    
   
    public MainServlet(){    
        super();    
      }    
    public void init() throws ServletException ...{    
          System.out.println("下面的两个参数param1是在servlet中存放的");    
          System.out.println(this.getInitParameter("param1"));    
          System.out.println("下面的参数是存放在servletcontext中的");    
          System.out.println(getServletContext().getInitParameter("context/param"));    
       }    
}

?第一种参数在servlet里面可以通过getServletContext().getInitParameter("context/param")得到

在JSP中可以用config.getServletContext().getInitParameter("context/param")得到

或者this.getServletContext().getInitParameter("context/param")

第二种参数只能在servlet的init()方法中通过this.getInitParameter("param1")取得.