web.xml上下文初始化參數

1、在web.xml文件中配置上下文參數

<!--<context-param>標簽聲明上下文初始化參數，  -->
  <!-- 上下文初始化的參數可以被應用程序用所有servlet共享 -->
  <context-param>
      <!-- 上下文參數可以像map一樣使用 -->
      <param-name>One</param-name><!-- 參數名 -->
      <param-value>hello</param-value><!-- 參數值 -->
  </context-param>
  <context-param>
      <param-name>Two</param-name>
      <param-value>dyf</param-value>
  </context-param>

 

2、在servlet中獲取上下文參數

//@WebServlet(name="HelloServlet01",value="/Hello")
@WebServlet(name="HelloServlet01",urlPatterns="/Hello")
public class HelloServlet01 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
        
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //創建一個獲取上下文參數的對象
        ServletContext context = this.getServletContext();
        //獲取上下文初始化的參數
        String initParameter = context.getInitParameter("One");
//        context.getInitParameterNames();
        PrintWriter writer = response.getWriter();
        //將參數返回到頁面
        writer.append(initParameter);
    }
}