我遇到的问题是，当我加载JSP时，它会返回一个空白页面。该页面应该使用参数“btnListar”调用Controller，并调用de DAO列出数据库中的条目。我调试了代码（我使用NetBeans来构建这个应用程序），并且值正在正确传递，变量填充了DAO获取的数据库中的条目，但浏览器应该显示的页面只是没有出现了，它是空白的。
我的控制器：
public class ExperienciaControle extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
String action = request.getParameter("action");
switch (action) {
case "btnCadastrar": {
Experiencia exp = new Experiencia();
exp.setEmpresa(request.getParameter("txtEmpresa"));
exp.setCargo(request.getParameter("txtCargo"));
exp.setData(request.getParameter("txtData"));
exp.setAtribuicoes(request.getParameter("txtAtrib"));
ExperienciaDAO dao = new ExperienciaDAO();
dao.insertExp(exp);
break;
}
case "btnAtualizar": {
Experiencia exp = new Experiencia();
exp.setEmpresa(request.getParameter("txtEmpresa"));
exp.setCargo(request.getParameter("txtCargo"));
exp.setData(request.getParameter("txtData"));
exp.setAtribuicoes(request.getParameter("txtAtrib"));
ExperienciaDAO dao = new ExperienciaDAO();
dao.updateExp(exp);
break;
}
case "btnRemover": {
Experiencia exp = new Experiencia();
exp.setId(Integer.parseInt(request.getParameter("chckId")));
ExperienciaDAO dao = new ExperienciaDAO();
dao.deleteExp(exp);
break;
}
case "btnListar": {
ExperienciaDAO dao = new ExperienciaDAO();
ArrayList<Experiencia> expArray = dao.selectExp();
request.setAttribute("expArray", expArray);
break;
}
default:
break;
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
@Override
public String getServletInfo() {
return "Short description";
}
}
我的JSP：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.util.*" %>
<%@ page import="Modelo.*" %>
<!DOCTYPE html>
<html>
<head>
<script src="../js/dropdown.js"></script>
<script src="../js/jquery-1.12.3.min.js"></script>
<script src="../js/lista.js"></script>
<link type="text/css" rel="stylesheet" href="../css/bootstrap.css" />
<link type="text/css" rel="stylesheet" href="../css/admin.css" />
<link type="text/css" rel="stylesheet" href="../css/dropdown.css" />
<link type="text/css" rel="stylesheet" href="../css/body.css" />
<link type="text/css" rel="stylesheet" href="../css/main.css" />
<link type="text/css" rel="stylesheet" href="../css/fonts.css" />
<title>Currículo | Administração</title>
</head>
<body>
<div class="body">
<div>
<nav id="primary_nav_wrap">
<ul>
<li class="current-menu-item"><a href="../">Home</a></li>
<li><a>Experiência</a>
<ul>
<li><a href="javascript:toggleDiv('divAddExp');">Adicionar</a></li>
<li><a href="javascript:toggleDiv('divUpdExp');">Listar</a></li>
</ul>
</li>
<li><a>Educação</a>
<ul>
<li><a href="#">Adicionar</a></li>
<li><a href="#">Atualizar</a></li>
<li><a href="#">Remover</a></li>
</ul>
</li>
<li><a>Habilidade</a>
<ul>
<li><a href="#">Adicionar</a></li>
<li><a href="#">Atualizar</a></li>
<li><a href="#">Remover</a></li>
</ul>
</li>
</ul>
</nav>
</div>
<div id="divAddExp" style="display:none" class="cadastros">
<form name="frmExp" action="../ExperienciaControle" method="POST">
<h1 style="font-family: Roboto">Cadastro de Experiência</h1><br />
<label for="lblEmpresa">Empresa </label><input type="text" name="txtEmpresa" class="form-control" /><br />
<label for="lblCargo">Cargo </label><input type="text" name="txtCargo" class="form-control" /><br />
<label for="lblData">Data </label><input type="text" name="txtData" class="form-control" /><br />
<label for="lblAtrib">Atribuições </label><textarea rows="4" cols="50" name="txtAtrib" class="form-control"></textarea><br />
<input class="btn" type="submit" name="btnCadastrar" value="Cadastrar" />
</form>
</div>
<div id="divUpdExp" class="cadastros">
<form name="frmExp" action="/ExperienciaControle" method="GET">
<h1 style="font-family: Roboto">Listagem de Experiência</h1><br />
<table>
<thead>
<tr>
<th> </th>
<th>ID</th>
<th>Empresa</th>
<th>Cargo</th>
</tr>
</thead>
<%
request.getRequestDispatcher("/ExperienciaControle?action=btnListar").forward(request, response);
ArrayList<Experiencia> expArray = (ArrayList<Experiencia>) request.getAttribute("expArray");
for (Experiencia exp : expArray) {
%>
<tr>
<td><input type="checkbox" name="chckID" value="<%= exp.getId()%>" /></td>
<td><%= exp.getId()%></td>
<td><%= exp.getEmpresa()%></td>
<td><%= exp.getCargo()%></td>
</tr>
<%
}
%>
</table>
<span><input class="btn" type="submit" name="btnListar" value="Listar" /></span>
<span><input class="btn" type="submit" name="btnAtualizar" value="Atualizar" /></span>
<span><input class="btn" type="submit" name="btnRemover" value="Remover" /></span>
</form>
</div>
</div>
</body>
</html>
如果我从JSP中删除Java代码并将其转换为纯HTML页面，它可以很好地工作，页面出现没有任何问题。 Tomcat（和Glassfish）日志显示没有错误消息，这使事情变得更加困难。 ：（
我在这里做错了什么？为什么我得到一个空白页？