Question

我正在尝试从mysql中保存数据并在另一个页面中检索它。我的保存部分成功但无法检索。它正在抛出此错误严重：带有路径[/ BackUp]的上下文中servlet [jsp]的Servlet.service（）引发异常[java.lang.NullPointerException]的根本原因显示java.lang.NullPointerException

AddEvents.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<h1 align="center">Add Event</h1>
<script>
function myFunction() {
    document.getElementById("myTime").value = "22:53:05";
}

function mySubmitFunction() {
    alert("You added an Event");
}
</script>

</head>
<body>
    <form action="AddEventsServlet" method="post" onsubmit="mySubmitFunction()">
        <table align="center" border= "10px" cellpadding="10">
<tr>
    <td>
        <label>Title      :</label><input type="text" name="Title" required>
    </td>
</tr>
<tr>
</tr>
<tr>
    <td>
<label>Details:</label><textarea rows="4" cols="15" name="EventDesc"></textarea>
    </td>
</tr>
<tr>
    <td>
Start time:<input type="time" id="myTime" name="StartTime">
    </td>
</tr>

<tr>
    <td>
End time:<input type="time" id="myTime" name="EndTime">
    </td>
</tr>

<tr>
<tr>
    <td>
Approximate Budget:<input type="text" id="budget" name="Budget">
    </td>
</tr>

<!--  <tr>
    <td>
Transportation:<select name="transportation" name="Transportation">
    <option value="Bus">Bus</option>
    <option value="MRT">MRT</option>
    <option value="Cab">Cab</option>
    <option value="Walk">Walk</option>
  </select>
    </td>
</tr>-->

<!--  -<tr>
    <td>
Environment: <input type="radio" name="Indoor" value="Indoor" name="Environment"> Indoor
  <input type="radio" name="Outdoor" value="Outdoor">Outdoor<br>
    </td>
</tr>

<tr>-->



<tr>
    <td>
<button type="submit" value="Add">Add</button>                <button type="reset" value="Reset">Reset</button>
    </td>

</tr>

        </table>
<a href="index.jsp">
<img border="0" alt="W3Schools" src="cal.jpg" width="50" height="50">
</a>




    </form>

</body>
</html>


AddEvents.java:
package model;

import java.sql.Date;
public class AddEvents {
 private String title;
 private String eventDesc;
 private String StartTime;
 private String  EndTime;
 private String Budget;
 //private String Transportation;
 //private String Environment;
public String getTitle() {
    return title;
}
public void setTitle(String title) {
    this.title = title;
}
public String getEventDesc() {
    return eventDesc;
}
public void setEventDesc(String eventDesc) {
    this.eventDesc = eventDesc;
}
public String getStartTime() {
    return StartTime;
}
public void setStartTime(String startTime) {
    StartTime = startTime;
}
public String getEndTime() {
    return EndTime;
}
public void setEndTime(String endTime) {
    EndTime = endTime;
}
public String getBudget() {
    return Budget;
}
public void setBudget(String budget) {
    Budget = budget;
}

Retrieve.jsp:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<%@page import="model.AddEvents" %>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h2>Events added</h2>
<!-- Retrieving the session
object AddEvents  and saved it
in a variable named myEvent  -->

<%!AddEvents myEvent;%>
<%myEvent=(AddEvents)session.getAttribute("iAddEvents"); %>

<table>
<tr><td>Title:</td><td><%= myEvent.getTitle() %></td></tr>
<tr><td>Details:</td><td><%= myEvent.getEventDesc() %></td></tr>
<tr><td>StartTime:</td><td><%=myEvent.getStartTime() %></td></tr>
<tr><td>EndTime:</td><td><%= myEvent.getEndTime() %></td></tr>
<tr><td>Budget:</td><td><%=myEvent.getBudget() %></td></tr>
</table>

</body>
</html>


AddEventsServlet:
package servlet;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import database.DBAO;
import model.AddEvents;

/**
 * Servlet implementation class AddEventsServlet
 */
@WebServlet("/AddEventsServlet")
public class AddEventsServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public AddEventsServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //doGet(request, response);

        AddEvents myEvent = new AddEvents();
        //create an object based on the Java class customers


        //Assignment of data
        myEvent.setTitle(request.getParameter("Title"));
        myEvent.setEventDesc(request.getParameter("EventDesc"));
        myEvent.setStartTime(request.getParameter("StartTime"));
        myEvent.setEndTime(request.getParameter("EndTime"));
        myEvent.setBudget(request.getParameter("Budget"));
        //myEvent.setTransportation(request.getParameter("Transportation"));
        //myEvent.setEnvironment(request.getParameter("Environment"));

        String title = request.getParameter("Title");
        String eventDesc= request.getParameter("EventDesc");
        //This will convert string to date format

        String StartTime=request.getParameter("StartTime");
        String EndTime =request.getParameter("EndTime");
        String Budget=request.getParameter("Budget");



        try
        {
            DBAO myDatabase = new DBAO();
            AddEvents myEventDetails =myDatabase.isEvent(myEvent,title, eventDesc, StartTime, EndTime, Budget);
            myDatabase.AddEvents(myEvent,title,eventDesc,StartTime,EndTime,Budget);

            if(myEventDetails!=null){
                HttpSession mySession = request.getSession(true);
                mySession.setAttribute("iAddEvents", myEvent);//setting the object named myEvent into the session
                request.getRequestDispatcher("Retrieve.jsp").forward(request,response);
            }
            else{
                request.getRequestDispatcher("AddEvent.jsp").forward(request,response);
            }

    }
        catch(Exception ex)
        {
            System.out.println("Error Accessing Database:" +ex);
        }

    }

}

严重：servlet的[Servlet.service（）[jsp]

0 个答案: