单击提交输入时，我从 <jsp:forward page="/myservlet" /> 无限循环

问题描述

我的jsp页面 web/jspPages/addReport.jsp

<%if(request.getParameter("addReport") != null){ %>
<jsp:forward page="/addReportGuiControlServlet" />
<%} %>

<form action="addReport.jsp" name="myform" method="POST">
    <h4 class="desc">How many people are there in the queue?</h4>
    <div>   
        <input class="addreport" type="checkBox" id="isLast" name="isLast">
        <label class="desc">I'm the last of the queue</label>
    </div>
    <div class="container1">
        <input class="addreport" type="text" name="queueLen" id="queueLen" autocomplete="off">
    </div>
    <div class="container2">    
        <input class="addreport" type="submit" name="addReport" value="Add Report">
    </div>
</form>

我的 servlet

@Override
public void doPost(HttpServletRequest request,HttpServletResponse response)
            throws servletexception,IOException
{
    
    Requestdispatcher rd = request.getRequestdispatcher("/jspPages/addReport.jsp");
    rd.forward(request,response);

}

我的 web.xml

<servlet>
    <servlet-name>AddReportGuiControlServlet</servlet-name>
    <servlet-class>logic.boundary.web.controlgrafico.AddReportGuiControlServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>AddReportGuiControlServlet</servlet-name>
    <url-pattern>/addReportGuiControlServlet</url-pattern>
</servlet-mapping>

导致无限循环的错误。我认为问题是参数“addReport”，因为在 servlet 中我尝试打印它并且是 != null，但我不知道如何设置这个值。

解决方法

我通过向 Servlet 中的 URL 添加一个参数来解决它：

RequestDispatcher rd = request.getRequestDispatcher("/jspPages/addReport.jsp?forward=true");

然后我将控件插入到 JSP 中：

<%if(request.getParameter("addReport") != null){
    //controllo se la pagina è stata già mandata dalla servlet

    if(request.getParameter("forward") == null){
    %>
        <jsp:forward page="/addReportGuiControlServlet"></jsp:forward>
    <%
    }
}
%>

这是因为参数 addReport 不为 null 则由 Servlet 转发