Java 无法分派到jsp页面

我试图运行我的程序，但似乎在它发布到servlet之后，它就停在那里，不会发送到下一个页面，只是一个带有PurchaseCreate上url的空白页面。我需要你的帮助

我的servlet位于源程序包下的controller文件夹下，JSP位于Web应用程序->Web页面->MemberAccess下，HTML位于Web应用程序->Web页面下

Servlet：

   public class PurchaseCreate extends HttpServlet {

    @PersistenceContext
    EntityManager em;
    @Resource
    UserTransaction utx;
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
         Members member = new Members();
            Stocks stock = new Stocks();
            Purchase purc = new Purchase();
            String purcid = null;
            String stockid = null;
            String purcdid = null;
            int quantity = 0 ;
            try (PrintWriter out = response.getWriter()) {


            int idNum = GeneratePdid();
            if(idNum<10)
                 purcdid = "PD0000"+idNum;
            else if(idNum<100)
                 purcdid = "PD000"+idNum;       
            else if(idNum<1000)
                 purcdid = "PD00"+idNum;
            else if(idNum<10000)
                 purcdid = "PD0"+idNum;
            else if(idNum<100000)
                 purcdid = "PD"+idNum;
            int PidNum = GeneratePid();
            if(PidNum<10)
                 purcid = "P000"+PidNum;
            else if(PidNum<100)
                 purcid = "P00"+PidNum;       
            else if(PidNum<1000)
                 purcid = "P0"+PidNum;
            else if(PidNum<10000)
                 purcid = "P"+PidNum;


            stockid = request.getParameter("stockid");
            stock.setStockid(stockid);
            purc.setPurchaseid(purcid);
            List<Stocks> listPrice = getStock(stockid);
            quantity = Integer.parseInt(request.getParameter("quantity"));
            Purchasedetails purchased = new Purchasedetails(purcdid,quantity,stock,purc);

            HttpSession session = request.getSession();
            session.setAttribute("purchased", purchased);
            session.setAttribute("listPrice", listPrice);

            RequestDispatcher rd = request.getRequestDispatcher("/MemberAccess/PurchaseCreateM.jsp");
               rd.forward(request, response);

        } catch (Exception ex) {
            Logger.getLogger(PurchaseCreate.class.getName()).log(Level.SEVERE, null, ex);
        } 
    }
 public List<Stocks> getStock(String stockid){
     Query query = em.createQuery("SELECT * FROM Stocks s WHERE s.stockid = :stockid").setParameter("stockid", stockid);
     List<Stocks> stockPrice = query.getResultList();
        return  stockPrice;
 }

public int GeneratePid(){  
            Query query = em.createNamedQuery("Purchase.findAll");
            List<Purchase> purchaseList = query.getResultList();
            String lastId = null;

                    if(!purchaseList.isEmpty()){
                        lastId = purchaseList.get(purchaseList.size()-1).getPurchaseid();
                    }
                String subString = lastId.substring(1,4);
                int realId = Integer.parseInt(subString) +1;
            return realId;   
         }

public int GeneratePdid(){
    Query query = em.createNamedQuery("Purchasedetals.findAll");
    List<Purchasedetails> purchaseDetailsL = query.getResultList();
    String lastId = null;


                    if(!purchaseDetailsL.isEmpty()){
                        lastId = purchaseDetailsL.get(purchaseDetailsL.size()-1).getPurchasedetailid();
                    }
                String subString = lastId.substring(2,6);
                int realId = Integer.parseInt(subString) +1;
            return realId;   

}

HTML:

  <h1>Purchase</h1>
    <form  action="../PurchaseCreate" method="post">

        <p>Please enter the fields below to make your purchase</p>
        <p>
            Stock ID :
            <input type ="text" name ="stock">&nbsp;
        </p>
        <p>Quantity :
            <input type="text" name="quantity">&nbsp;
        </p>
            <input type="submit" name="create" class ="button" value="Add into cart">

    </form> 

JSP:

---

这是因为您正在try/catch块中调用调度程序。在catch块中，除了记录异常之外，您什么也不做。如果您将带有dispatcher的代码移出try/catch块，那么即使您有错误，它也应该被分派。使用更改代码

}捕获异常{ Logger.getLoggerPurchaseCreate.class.getName.logLevel.SEVERE，null，ex； } RequestDispatcher rd=request.getRequestDispatcher/MemberAccess/PurchaseCreateM.jsp； 请求、响应；

---

不过，我看不到任何变化。它仍然是一个空白页。您正在查看什么样的更改？因为我设置了属性并获取了属性，所以如果它连接到jsp，是否应该显示该表？不，您弄错了。如果您的代码在与数据库通信时抛出异常，则不会填充属性。@user3900009不要在JSP中使用Scriptlet。getter和setter不足以显示一个表，但是使用with EL可以用foreach标记填充它。

 <% List<Purchasedetails> list = (List<Purchasedetails>)request.getAttribute("purchased"); %>
     <% List<Stocks> listPrice = (List<Stocks>)request.getAttribute("listPrice"); %>
     <% int size= list.size(); %>
     <%! String pDID = "";%>
     <%! int pDIDno = 0; %>
     <%! String pDIDSub = ""; %>
     <%! String pDIDreal = ""; %>
     <body>
          <% if (size != 1){ %>
     <% pDID = list.get(list.size()-1).getPurchasedetailid(); %>
     <% pDIDSub = pDID.substring(2, 6); %>
     <% pDIDno = Integer.parseInt(pDIDSub) + (size-1);}%>
     <% if(pDIDno<10)
                 pDIDreal = "PD0000"+pDIDno;
            else if(pDIDno<100)
                 pDIDreal = "PD000"+pDIDno;       
            else if(pDIDno<1000)
                 pDIDreal = "PD00"+pDIDno;
            else if(pDIDno<10000)
                 pDIDreal = "PD0"+pDIDno;
            else if(pDIDno<100000)
                 pDIDreal = "PD"+pDIDno;

                  list.get(list.size()-1).setPurchasedetailid(pDIDreal);
     %>
   <table border="1">
            <thead>
                <tr>
                    <th>No.</th>
                    <th>Purchase Details ID</th>
                    <th>Stock ID</th>
                    <th>Quantity</th>
                    <th>Price</th>
                </tr>
            </thead>
            <tbody>

                <% for (int i = 1; i <list.size(); i++) { %>

                <tr>
                    <td><%= i-1 %></td>
                    <td><%= list.get(i).getPurchasedetailid() %></td>
                    <td><%= list.get(i).getStockid()  %></td>
                    <td><%= list.get(i).getOrderqty() %></td>
                    <td><%= listPrice.get(i).getStockprice() %></td>
                </tr>
                <% i++;%>
                <% } %>
            </tbody>
        </table>
     </body>