好的，这是问题所在。每当我运行PurchaseM.jsp时，当我重定向到PurchaseCheckOut.java时，我将获得http status 404 - not found。我不知道为什么会这样。如果我从PurchaseCart.jsp开始，我已经有会话值（所以没有空例外），那么它将运行。有人帮我请。
PurchaseM.jsp
<%@ taglib prefix = "c" uri = "http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
<html>
<head>
<title>Purchasing</title>
</head>
<body>
<h1>Purchase</h1>
<sql:setDataSource url="jdbc:derby://localhost:1527/healthdb;user=nbuser;password=nbuser" driver="org.apache.derby.jdbc.ClientDriver"
var="Derbydata"/>
<sql:query sql=" SELECT stockid FROM STOCKS" dataSource="${Derbydata}" var="STOCKS" />
<form action="../PurchaseCreate" method="post">
<p>Please enter the fields below to make your purchase</p>
<strong>Select a product :</strong>
<select name="stockid">
<c:forEach var="row" items="${STOCKS.rowsByIndex}">
<option><c:out value="${row[0]}"/></option>
</c:forEach>
</select>
</p>
<p><strong>Quantity</strong> :
<input type="text" name="quantity">
</p>
<input type="submit" name="create" class ="button" value="Add into cart">
</form>
</body>
</html>
PurchaseCreate.java
package controller;
import entity.Login;
import entity.LoginPK;
import entity.Purchasedetails;
import entity.Members;
import entity.Purchase;
import entity.Stocks;
import java.io.*;
import java.math.BigDecimal;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Random;
import java.util.logging.*;
import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.*;
import javax.transaction.UserTransaction;
import model.PurchaseService;
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();
PurchaseService ps = new PurchaseService(em);
String purcid = "";
stock.setStockid(request.getParameter("stockid"));
String stockid = stock.getStockid();
String purcdid = "";
int quantity = 0 ;
PrintWriter out = response.getWriter();
try{
out.println(stockid);
out.println("Hello");
int idNum = GeneratePdid();
if(idNum<10)
purcdid = "PD0000"+String.valueOf(idNum);
else if(idNum<100)
purcdid = "PD000"+String.valueOf(idNum);
else if(idNum<1000)
purcdid = "PD00"+String.valueOf(idNum);
else if(idNum<10000)
purcdid = "PD0"+String.valueOf(idNum);
else if(idNum<100000)
purcdid = "PD"+String.valueOf(idNum);
int PidNum = GeneratePid();
if(PidNum<10)
purcid = "P000"+String.valueOf(PidNum);
else if(PidNum<100)
purcid = "P00"+String.valueOf(PidNum);
else if(PidNum<1000)
purcid = "P0"+String.valueOf(PidNum);
else if(PidNum<10000)
purcid = "P"+String.valueOf(PidNum);
out.println("Hello");
out.println(stockid);
stock.setStockid(stockid);
out.println(purcid);
purc.setPurchaseid(purcid);
out.println(purcdid);
out.println("Hello");
quantity = Integer.parseInt(request.getParameter("quantity"));
out.println(quantity);
Purchasedetails purchased = new Purchasedetails(purcdid,quantity,stock,purc);
out.println(stock);
out.println(purc);
double stockPriceReal = getStock(stockid);
out.print(stockPriceReal);
HttpSession session = request.getSession();
session.setAttribute("purchased",purchased);
session.setAttribute("stockPriceReal",stockPriceReal);
out.print(stockPriceReal);
RequestDispatcher rd = request.getRequestDispatcher("MemberAccess/PurchaseCart.jsp");
rd.forward(request, response);
} catch (Exception ex) {
ex.printStackTrace();
}
finally{
out.close();
}
}
public int GeneratePid(){
Query query = em.createNamedQuery("Purchase.findAll");
List<Purchase> purchaseList = query.getResultList();
String lastId = "";
int realId = 0;
if(!purchaseList.isEmpty()){
lastId = purchaseList.get(purchaseList.size()-1).getPurchaseid();
String subString = lastId.substring(1,5);
realId= Integer.parseInt(subString) +1;
}
return realId;
}
public int GeneratePdid(){
Query query = em.createNamedQuery("Purchasedetails.findAll");
List<Purchasedetails> purchaseDetailsL = query.getResultList();
String lastId = "";
if(!purchaseDetailsL.isEmpty()){
lastId = purchaseDetailsL.get(purchaseDetailsL.size()-1).getPurchasedetailid();
}
String subString = lastId.substring(2,7);
int realId = Integer.parseInt(subString) +1;
return realId;
}
private double getStock(String stockid) {
Query query2 = em.createNamedQuery("Stocks.findAll");
List<Stocks> stockPrice = query2.getResultList();
double stockPriceReal = 0;
for(int i = 0 ; i <stockPrice.size(); i++){
String stockid2 = stockPrice.get(i).getStockid();
if(stockid2.equals(stockid))
{
stockPriceReal = Double.parseDouble(stockPrice.get(i).getStockprice().toString());
}
} return stockPriceReal;
}
}
PurchaseCart.jsp
<%@page import="javax.persistence.Query"%>
<%@page import="java.util.ArrayList"%>
<%@page import="model.*"%>
<%@page import="java.util.List"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<html>
<head>
<title>Cart</title>
</head>
<body>
<%!List<Double> stockArray = new ArrayList<Double>() ;%>
<%!List<Object> list1 = new ArrayList<Object>();%>
<% Object o = session.getAttribute("purchased");
list1.add(o);
int size = list1.size();
double stockPrice = (Double)session.getAttribute("stockPriceReal");
if(stockArray.size() == 0)
{
stockArray.add(stockArray.size(),stockPrice);
}
else {
stockArray.add(stockArray.size(), stockPrice); }
%>
<table border="1">
<thead>
<tr>
<th>No.</th>
<th>Purchase Details ID</th>
<th>Quantity</th>
<th>Stock ID</th>
<th>Price</th>
</tr>
</thead>
<tbody>
<% for (int g = 0; g < size; g ++) { %>
<tr>
<%! String finalSubString1 = "";
int subInt = 0;
int subIntP = 0; %>
<% String toString = list1.get(g).toString();
String subString1 = toString.substring(2,7);
subInt = Integer.parseInt(subString1)+ g;
if(subInt<10)
finalSubString1 = "PD0000"+String.valueOf(subInt);
else if(subInt<100)
finalSubString1 = "PD000"+String.valueOf(subInt);
else if(subInt<1000)
finalSubString1 = "PD00"+String.valueOf(subInt);
else if(subInt<10000)
finalSubString1 = "PD0"+String.valueOf(subInt);
else if(subInt<100000)
finalSubString1 = "PD"+String.valueOf(subInt);
String subString2 = toString.substring(7,9);
String subString3 = toString.substring(9,15);
String subString4 = toString.substring(15,19);
%>
<td><%= g +1 %></td>
<td><%= finalSubString1 %></td>
<td><%= subString2 %></td>
<td><%= subString3 %></td>
<td><%= stockArray.get(g).toString() %></td>
</tr>
<% } %>
</tbody>
</table>
<% session.setAttribute("stockArray",stockArray);
session.setAttribute("list1",list1);%>
<form action = "../PurchaseUpdateM" >
<input type ="submit" name ="update" class="button" value="Update" >
</form>
<form action ="../PurchaseCheckOut" method="POST" >
<input type = submit name="checkout" class ="button" value="Check Out">
</form>
<form action="MemberAccess/PurchaseM.jsp" >
<input type ="submit" name="continue" class="button" value="Continue Shopping">
</form>
</body>
</html>
PurchaseCheckOut.java
package controller;
import entity.Login;
import entity.LoginPK;
import entity.Members;
import entity.Purchasedetails;
import model.PurchaseService;
import entity.Purchase;
import entity.Stocks;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.transaction.Transactional;
import javax.transaction.UserTransaction;
public class PurchaseCheckOut extends HttpServlet {
@PersistenceContext
EntityManager em;
@Resource
UserTransaction utx;
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
int count = 0;
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=UTF-8");
try {
Stocks stock = new Stocks();
HttpSession session = request.getSession();
List<Object> list2 = (List<Object>) session.getAttribute("list1");
PurchaseService ps = new PurchaseService(em);
for(int i = 0; i < list2.size();i++){
list2.get(i).toString();
String toString = list2.get(i).toString();
String subString1 = toString.substring(2,7);
int subInt = 0;
String finalSubString1 ="";
subInt = Integer.parseInt(subString1)+ i;
if(subInt<10)
finalSubString1 = "PD0000"+String.valueOf(subInt);
else if(subInt<100)
finalSubString1 = "PD000"+String.valueOf(subInt);
else if(subInt<1000)
finalSubString1 = "PD00"+String.valueOf(subInt);
else if(subInt<10000)
finalSubString1 = "PD0"+String.valueOf(subInt);
else if(subInt<100000)
finalSubString1 = "PD"+String.valueOf(subInt);
String subString2 = toString.substring(7,9);
String subString3 = toString.substring(9,15);
String subString4 = toString.substring(15,20);
stock.setStockid(subString3);
String loginId = "abc";
String memberId = "M0001";
String password = "gay";
LoginPK logPK = new LoginPK(loginId,memberId);
Login log = new Login(logPK, password);
session.setAttribute("log", log);
Login j = (Login) session.getAttribute("log");
// out.print(j.getLoginPK().getMemberId());
String mem = j.getLoginPK().getMemberId();
Members member = new Members();
member.setMemberId(mem);
Date date = new Date();
DateFormat strformat = new SimpleDateFormat ("yyyy/MM/dd",Locale.ENGLISH);
String date2 = strformat.format(date);
Date date3 = strformat.parse(date2);
Purchase purchase= new Purchase(subString4,date3,member);
Purchasedetails pd = new Purchasedetails(finalSubString1,Integer.parseInt(subString2),stock,purchase);
out.println(purchase.getPurchaseid());
out.println(stock.getStockid());
if(count == 0){
utx.begin();
ps.addPurchase(purchase);
utx.commit();
count ++;
}
utx.begin();
ps.addPurchasedetails(pd);
utx.commit();
}
session.removeAttribute("stockArray");
session.removeAttribute("list1");
session.removeAttribute("purchased");
session.removeAttribute("stockPriceReal");
response.sendRedirect("/MemberAccess/PurchaseAddConfirm.jsp");
} catch (Exception ex) {
Logger.getLogger(PurchaseCheckOut.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
编辑：
<servlet-name>PurchaseM</servlet-name>
<jsp-file>/MemberAccess/PurchaseM.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>PurchaseM</servlet-name>
<url-pattern>/MemberAccess/PurchaseM.jsp</url-pattern>
</servlet-mapping>