Question

在我提交作业之前，老师告诉我，该项目的一个要求是使用servletcontextlistener。我阅读了所有相关内容，但我没有实际操作技能。有人可以解释我如何在我的程序中轻松实现这个方法，它仍然有用吗？谢谢。

任务是建立一个网站（前端）并制作一个表格（后端）。这是servlet代码，我认为你不需要看到HTML和JavaScript。

      @WebServlet("/ServletProjekt")
      public class ServletProjekt extends HttpServlet{
      private static final long serialVersionUID = 1L;


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    String firstName = request.getParameter("förnamn");
    String lastName = request.getParameter("efternamn");
    String address = request.getParameter("address");
    String email = request.getParameter("email");
    String howoften = request.getParameter("howoften");
    String newsabout = request.getParameter("news");
    String[] age = request.getParameterValues("age");


    Cookie firstname = new Cookie ("firstname", firstName);
    Cookie lastname = new Cookie ("lastname", lastName);
    Cookie Address = new Cookie ("Address", address);
    Cookie mail = new Cookie ("mail", email);
    Cookie HowOften = new Cookie ("HowOften?", howoften);
    Cookie news = new Cookie ("news", newsabout);

    firstname.setMaxAge(60 * 60 * 24);
    lastname.setMaxAge(60 * 60 * 24);
    Address.setMaxAge(60 * 60 * 24);
    mail.setMaxAge(60 * 60 * 24);
    HowOften.setMaxAge(60 * 60 * 24);
    news.setMaxAge(60 * 60 * 24);

    response.addCookie(firstname);
    response.addCookie(lastname);
    response.addCookie(Address);
    response.addCookie(mail);
    response.addCookie(HowOften);
    response.addCookie(news );



        response.setContentType("text/html");
        PrintWriter printWriter = response.getWriter();
        printWriter.write("<html>");
        printWriter.write("<h1> THANK YOU FOR YOUR INFORMATION</h1>");
        printWriter.write("<body>");
        printWriter.write("<p>Your name:</p>" + firstName);
        printWriter.write("<br>");
        printWriter.write("<p>Your last name:</p>" +lastName + "<br>");
        printWriter.write("<p>Your address:</p>" +address + "<br>");
        printWriter.write("<p>Your choice of often:</p>" +howoften + "<br>");
        printWriter.write("<p>Your choice of news:</p>" +newsabout + "<br>");
        printWriter.write("<p>Your email:</p>" +email + "<br>");

        for (String ages : age) {
            printWriter.write("<p>Your age:</p>" +ages + "<br>");
        }

        printWriter.write("<a href =\"GetAllCookies\">View All Cookies</a>");

        printWriter.write("</body>");
        printWriter.write("</html>");

}

}

Answer 1

实现以下界面：

javax.servlet.ServletContextListener

并在web.xml中包含以下内容（将类名替换为正确的名称）：

<listener>
    <listener-class>com.something.MyContextListener</listener-class>
</listener>

Answer 2

首先你需要像这样创建

public class yourServletContextListener 
           implements ServletContextListener{

@Override
public void contextDestroyed(ServletContextEvent arg0) {
    System.out.println("ServletContextListener destroyed");
}

    //Run this before web application is started
@Override
public void contextInitialized(ServletContextEvent arg0) {
    System.out.println("ServletContextListener started");   
}

}

并将其写入您的web.xml

<listener>
<listener-class>
        fully qualified name for  yourServletContextListener 
    </listener-class>

如何在程序中实现servletcontextlistener？

2 个答案: