读取容器配置参数---context-param和init-param
web.xml里面可以定义两种参数:
(1)application范围内的参数,存放在servletcontext中,在web.xml中配置如下:
(1)application范围内的参数,存放在servletcontext中,在web.xml中配置如下:
- <context-param>
- <param-name>context/param</param-name>
- <param-value>avalible during application</param-value>
- </context-param>
<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>
<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:
- 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"));
- }