如何将相同的参数从一个JSP传递给两个servlet？然后将不同的参数从servlet传递到同一个JSP？

Question

我是Web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！！我们应该先做过程A，然后再做过程B！！！！

由于项目需要太多进程，我想将这些进程分成两个servlet。

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

我使用的代码是：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);

          }  
                }

那么如何在系统中实现processB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！！我们应该先做过程A，然后再做过程B！！！！

Answer 1

对于您的SearchPage表单，只能有一种操作方法（get/post等）。jsp。

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

这两种方法有不同的目的检查这里的差异

您必须将处理单元A和B保持在单个servlet（servlet A/servlet B）中，例如：首先从JSP调用进程A，然后从进程A调用进程B，最后将响应重定向/转发到Welcome。jsp来自流程B
以下是代码：

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：您可以按要求执行相反的操作，即先调用doPost，然后再调用doGet。此外，需要为此更改表单标签中的方法。

对于您在评论中的查询，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);  
  }