所以,我试图从下拉列表中获取值并将它们添加到ArrayList中,以便以后可以显示它,但我不知道该怎么做?
基本上,当用户按下next(发送)按钮时,servlet应该获取values参数,并将其存储到arraylist中供以后使用,并且应该将它们定向回表单页面,以便他们可以进行更多选择或按一下done(list)按钮
来查看他们选择了哪些选项Servlet(水果Servlet)
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=UTF-8");
String wasSent = request.getParameter("send");
String Submitted = request.getParameter("list");
ArrayList<Double> fruitsList = new ArrayList<Double>();
if (wasSent != null) {
String fruits = request.getParameter("Values");
fruitsList.add(fruits);
request.setAttribute("List", fruitsList);
RequestDispatcher rs = request.getRequestDispatcher("form.html");
rs.forward(request, response);
} else if (Submitted != null) {
//get the list and display all the values
}
}
答案 0 :(得分:0)
在您的servlet中,您可以使用session在数组中设置值,这样该值将被保存,直到您从会话中将其删除为止。您的代码如下所示:
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=UTF-8");
String fruits = request.getParameter("Values");
ArrayList<String> fruitsList1 = new ArrayList<String>();
//get values which are in session
ArrayList<String> fruitsList = (ArrayList<String>)request.getSession().getAttribute("List");
//if attribute value is not null
if (fruitsList != null) {
//add new values
fruitsList.add(fruits);
request.getSession().setAttribute("List", fruitsList);
RequestDispatcher rs = request.getRequestDispatcher("form.html");
rs.forward(request, response);
} else if (fruitsList== null) {
//adding value selected in array list
fruitsList1.add(fruits);
//setting values
request.getSession().setAttribute("List", fruitsList1);
RequestDispatcher rs = request.getRequestDispatcher("form.html");
rs.forward(request, response);
} else{
//remove values
}
}