java - 如何将相同的参数从一个 JSP 传递到两个 servlet？然后将不同的参数从servlet传递到同一个JSP？

Question

我是网络应用程序的新手。 我的问题:如何将相同的参数从一个 JSP 传递到两个 servlet？然后将不同的参数从servlet传递到同一个JSP？

重要!!我们应该先执行过程A，然后执行过程B!!!

由于该项目需要太多进程，我想将这些进程分成两个servlet。

目前，我完成了processA的实现，即将搜索词从SEARCH PAGE JSP传递到SERVLET A(执行processA)并将结果传递到WELCOME PAGE JSP。它有效!!!(我在图片中以红色突出显示)

我使用的代码: Web.xml

  <servlet>
    <servlet-name>ServletA</servlet-name>
    <servlet-class>test.processA</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ServletA</servlet-name>
    <url-pattern>/download result</url-pattern>
  </servlet-mapping>

搜索页面 JSP:

<form   action="download result">           
             Please enter a Keyword <br> 
            <input type="text" name="term"size="20px">
            <input type="submit" value="submit">

</form>

servletA:

public class processA  extends HttpServlet { 
     protected void doGet(HttpServletRequest request, 
              HttpServletResponse response) throws ServletException, IOException 
          {
            // reading the user input

            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            // Retrieve search term from GET request and parse to desired format
            String searchTerm = (request.getParameter("term").toString()).replace("%20", "_").replace(" ", "_").replace("+", "_").replace(".", "");
            System.out.println("=====(servlet) searchTerm is:"+searchTerm);

  }

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

          }  
                }

那么如何将processB实现到系统中呢？？？看起来就像我展示的图片。

servletB

public class processB extends HttpServlet {
    protected void doGet(HttpServletRequest request,  HttpServletResponse response) throws ServletException, IOException 
          {
            doPost(request,response);
          }


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



        String searchTerm = (request.getParameter("term")).replace(" ", "_");
        String queryTerm = request.getParameter("term");

        System.out.println("=====(servlet) searchTerm is:"+searchTerm);

System.out.println("=====(servlet) keep doing the other process……………………!!!”);


}
}

非常感谢! 或者如果doGET和doPOST不能同时使用，我可以将processA更改为doPost。

重要!!我们应该先执行过程A，然后执行过程B!!!

Answer 1

SearchPage.jsp 表单只能有一种操作方法(获取/发布等)。

作为程序员，您必须首先决定需要处理什么内容以及如何处理请求，而不是让用户在 doPost 和 doGet 方法之间进行选择。

两种方法都有不同的用途，查看区别here

您必须将处理单元 A 和 B 保留在单个 servlet 中(servletA/servletB)，
例如:首先从 JSP 调用进程 A，然后从 进程 A 调用进程 B，最后重定向/转发来自 Process B 对 Welcome.jsp 的响应
下面是代码:

Search.jsp

<form action="download result" method="get">
...
</form>

servletA:

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
      {
        ... //processing logic of A
        ... //processing logic of A
        ... //processing logic of A
        doPost(request,response);//call Post 
      }
 protected void doPost(HttpServletRequest request,  HttpServletResponse response) throws ServletException, IOException 
  {
        ... //processing logic of B
        ... //processing logic of B
        ... //processing logic of B

        RequestDispatcher rd=request.getRequestDispatcher("welcome.jsp");  
        rd.forward(request, response);  
  }

注意:反之亦然，即根据您的要求先调用doPost，然后再调用doGet。另外，需要为此更改 form 标记 中的 method="post" 。

<小时/>

对于评论中的查询，请使用以下代码:

servletA:

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
      {
        ... //processing logic of A
        ... //processing logic of A
        ... //processing logic of A
        RequestDispatcher dispatcher = null;
        dispatcher=request.getRequestDispatcher("servletB");
        dispatcher.forward(request, response);//call Post 
      }

servletB:

 protected void doPost(HttpServletRequest request,  HttpServletResponse response) throws ServletException, IOException 
  {
        ... //processing logic of B
        ... //processing logic of B
        ... //processing logic of B

        RequestDispatcher rd=request.getRequestDispatcher("welcome.jsp");  
        rd.forward(request, response);  
  }