web.xml上下文初始化参数

1、在web.xml文件中配置上下文参数

 1 <!--<context-param>标签声明上下文初始化参数，  -->
 2   <!-- 上下文初始化的参数可以被应用程序用所有servlet共享 -->
 3   <context-param>
 4       <!-- 上下文参数可以像map一样使用 -->
 5       <param-name>One</param-name><!-- 参数名 -->
 6       <param-value>hello</param-value><!-- 参数值 -->
 7   </context-param>
 8   <context-param>
 9       <param-name>Two</param-name>
10       <param-value>dyf</param-value>
11   </context-param>

2、在servlet中获取上下文参数

 1 //@WebServlet(name="HelloServlet01",value="/Hello")
 2 @WebServlet(name="HelloServlet01",urlPatterns="/Hello")
 3 public class HelloServlet01 extends HttpServlet {
 4     private static final long serialVersionUID = 1L;
 5 
 6     public void doGet(HttpServletRequest request, HttpServletResponse response)
 7             throws ServletException, IOException {
 8         this.doPost(request, response);
 9         
10     }
11 
12     public void doPost(HttpServletRequest request, HttpServletResponse response)
13             throws ServletException, IOException {
14         //创建一个获取上下文参数的对象
15         ServletContext context = this.getServletContext();
16         //获取上下文初始化的参数
17         String initParameter = context.getInitParameter("One");
18 //        context.getInitParameterNames();
19         PrintWriter writer = response.getWriter();
20         //将参数返回到页面
21         writer.append(initParameter);
22     }
23 }