Sql web应用程序-JSP中搜索查询中的java.lang.NullPointerException
我试图访问我的数据库获取信息，但它一直抛出一个空异常 我调用了对象和技术人员对象/ addTech.jsp：Sql web应用程序-JSP中搜索查询中的java.lang.NullPointerException,sql,jsp,jpa,web-applications,Sql,Jsp,Jpa,Web Applications,我试图访问我的数据库获取信息，但它一直抛出一个空异常 我调用了对象和技术人员对象/ addTech.jsp： <%@page import="com.example.backend.BackendFactory"%> <%@page import="java.util.ArrayList"%> <%@page import="com.example.model.*"%> <%@ page language="java" contentType="
<%@page import="com.example.backend.BackendFactory"%>
<%@page import="java.util.ArrayList"%>
<%@page import="com.example.model.*"%>
<%@ page language="java" contentType="text/html; charset=windows-1255"
pageEncoding="windows-1255"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Adding Tech</title>
</head>
<%
String TechId, TechName, TechUserName, TechPass, TechPassVer, TechRank, TechSecQ, TechSecA, TechEmail, TechPhone;
TechName = request.getParameter("TechName");
TechUserName = request.getParameter("TechUserName");
TechPass = request.getParameter("TechPass");
TechPassVer = request.getParameter("TechPassVer");
TechRank = request.getParameter("TechRank");
TechSecQ = request.getParameter("TechSecQ");
TechSecA = request.getParameter("TechSecA");
TechEmail = request.getParameter("TechEmail");
TechPhone = request.getParameter("TechPhone");
if (TechName != null && TechUserName != null && TechPass != null
&& TechPassVer != null && TechRank != null
&& TechSecQ != null && TechSecA != null
&& TechEmail != null && TechPhone != null)
{
Technician t = new Technician(TechName, TechUserName, TechPass,
new ArrayList<Call>(), TechnicianRank.Beginner,
TechSecQ, TechSecA, TechPhone, TechEmail, (float) 0.0);
BackendFactory.getInstance().addTechnician(t);
}
%>
<body>
<h1>Adding Technican</h1>
<form name="tempForm" action="addTech.jsp" method="get">
<table align="left" border="0" cellpadding="1" cellspacing="1"
style="width: 500px;">
<tbody>
<tr>
<td><strong style="color: rgb(255, 0, 0);"><u>Tech
Details:</u></strong></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td>Id:</td>
<td><input name="TechId" readonly="readonly" type="text"
value=<%out.print(BackendFactory.getInstance().getTechnicianCurrentId());%> /></td>
</tr>
<tr>
<td> </td>
<td>Name:</td>
<td><input name="TechName" type="text" value="Your first name" /></td>
</tr>
<tr>
<td> </td>
<td>User name:</td>
<td><input name="TechUserName" type="text"
value="Your last name" /></td>
</tr>
<tr>
<td> </td>
<td>Password:</td>
<td><input name="TechPass" type="password" /></td>
</tr>
<tr>
<td> </td>
<td>Verify Password:</td>
<td><input name="TechPassVer" type="password" /></td>
</tr>
<tr>
<td> </td>
<td>Rank:</td>
<td><input name="TechRank" readonly="readonly" type="text"
value="Beginer" /></td>
</tr>
<tr>
<td> </td>
<td>Security Q:</td>
<td><input name="TechSecQ" size="30" type="text"
value="Whats your grandmother birth?" /></td>
</tr>
<tr>
<td> </td>
<td>Security A:</td>
<td><input name="TechSecA" size="30" type="text"
value="Dont remember..." /></td>
</tr>
<tr>
<td> </td>
<td>Email:</td>
<td><input name="TechEmail" type="text"
value="example@gmail.com" /></td>
</tr>
<tr>
<td> </td>
<td>Phone:</td>
<td><input name="TechPhone" type="text" value="0123456789" /></td>
</tr>
<tr>
<td> </td>
<td> </td>
<td><input name="addTech" type="submit" value="Submit" /></td>
</tr>
</tbody>
</table>
</form>
</body>
</html>
添加技术
添加技术员
科技
详细信息：
身份证件：
姓名：
用户名：
密码：
验证密码：
排名：
安全问题：
保安A：
电邮：
电话：
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@page import="com.google.gwt.dom.client.SelectElement"%>
<%@page import="sun.reflect.CallerSensitive"%>
<%@page import="java.util.List"%>
<%@page import="java.util.ArrayList"%>
<html>
<%@page import="com.example.model.*"%>
<%@page import="com.example.backend.BackendFactory"%>
<%@page import="com.example.backend.ServerBackend"%>
<%@ page language="java" contentType="text/html; charset=windows-1255"
pageEncoding="windows-1255"%>
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=windows-1255">
<title>Insert title here</title>
</head>
<body>
<h1>Adding Call
<%/*out.print(backend.findTechByName("sabag"));*/%>
</h1>
<form name="tempForm" action="addCall.jsp" method="get">
<%!ServerBackend backend = BackendFactory.getInstance();%>
<%
/*backend.addTechnician(new Technician());*/
//
String desc, tech, techRank, ClientAddress, ClientFirst, ClientLast;
desc = request.getParameter("desc");
tech = request.getParameter("tech");
ClientAddress = request.getParameter("ClientAddress");
ClientFirst = request.getParameter("ClientFirst");
ClientLast = request.getParameter("ClientLast");
Technician t=null ;
if (tech != null)
{
try
{
t=backend.findTechByName(tech);
} catch (Exception e)
{
t = new Technician();
t.setName(tech);
backend.addTechnician(t);
}
}
if (desc != null && tech != null && ClientAddress != null
&& ClientFirst != null && ClientLast != null)
{
Call call = new Call();
call.setDescription(desc);
call.setCaller(new Client(ClientFirst + ClientLast,
new Address(ClientAddress, ClientAddress,
ClientAddress, 45)));
call.setTechnician(t);
backend.addCall(call);
}
/**/
%>
<table align="left" border="0" cellpadding="1" cellspacing="1"
style="width: 500px;">
<tbody>
<tr>
<td><strong style="color: rgb(255, 0, 0);"><u>Call
Details:</u></strong></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td>Id:</td>
<td>
<div>
<input name="id" readonly="readonly" type="text"
value=<%out.print(backend.getCallCurrentId());%> />
</div>
</td>
</tr>
<tr>
<td> </td>
<td>Description:</td>
<td><textarea name="desc"></textarea></td>
</tr>
<tr>
<td> </td>
<td>Technician:</td>
<td><select name="tech" size="1">
<%
try
{
List<String> lst=backend.getAllTechsNames();
for(String s : lst) {
%>
<option value="100">
<%
out.print(s);
%>
</option>
<%
}
}
catch(Exception e)
{
%>
<option>
<%
out.println("fdghjk");
%>
</option>
<%
}
%>
</select> </td>
</tr>
<tr>
<td><strong><u><span
style="color: rgb(255, 0, 0);">Caller Details:</span></u></strong></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td>First name</td>
<td><input name="ClientFirst" type="text"
value="Your first name" /></td>
</tr>
<tr>
<td> </td>
<td>Last name</td>
<td><input name="ClientLast" type="text"
value="Your last name" /></td>
</tr>
<tr>
<td> </td>
<td>Address</td>
<td><input name="ClientAddress" type="text"
value="Your address" /></td>
</tr>
<tr>
<td> </td>
<td> </td>
<td><input name="addCall" type="submit" value="Submit" /></td>
</tr>
</tbody>
</table>
</form>
</body>
</html>
在此处插入标题
添加呼叫
调用
详细信息：
身份证件：
说明：
技术员：
来电者详细信息：
名字
姓
住址
package com.example.backend;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import javax.persistence.TypedQuery;
import com.example.model.Call;
import com.example.model.CallStatus;
import com.example.model.SparePart;
import com.example.model.Technician;
import com.example.model.ThingToDo;
public class DBbackend implements Backend
{
private EntityManagerFactory emf = null;
private EntityManager em = null;
private String PERSISTENCE_UNIT_NAME = "transactions-optional";
//
public DBbackend()
{
emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
em = emf.createEntityManager();
}
private void insert(Object obj) throws Exception
{
em.getTransaction().begin();
em.persist(obj);
try
{
em.getTransaction().commit();
} catch (Exception e)
{
em.clear();
throw e;
}
}
@Override
public int getNextCallId()
{
// TODO Auto-generated method stub
return 0;
}
@Override
public void removeCall(int id) throws Exception
{
// TODO Auto-generated method stub
}
@Override
public ArrayList<Call> getCallsByTech(Technician t) throws Exception
{
// TODO Auto-generated method stub
return null;
}
@Override
public void updateCall(Call call) throws Exception
{
// TODO Auto-generated method stub
}
@Override
public void save()
{
// TODO Auto-generated method stub
}
@Override
public void addCall(Call call) throws Exception
{
// TODO Auto-generated method stub
}
@Override
public void addTechnician(Technician technician) throws Exception
{
// TODO Auto-generated method stub
insert(technician);
}
@Override
public Technician getTechnicianByUserName(String userName) throws Exception
{
// TODO Auto-generated method stub
return null;
}
@Override
public Call getCall(int id) throws Exception
{
// TODO Auto-generated method stub
return null;
}
@Override
public void addCallToTech(Call call, Technician t) throws Exception
{
// TODO Auto-generated method stub
call.setTechnician(t);
insert(call);
}
@Override
public Technician findTechByName(String name) throws Exception
{
// TODO Auto-generated method stub
Query q = em.createQuery(
"SELECT technician FROM Technician technician "
+ "WHERE technician.name = :Name ", Technician.class);
q.setParameter("Name", name);
return (Technician) q.getSingleResult();
}
@SuppressWarnings("unchecked")
@Override
public List<String> getAllTechsNames() throws Exception
{
// TODO Auto-generated method stub
TypedQuery<Technician> query =
em.createQuery("SELECT p FROM Technician p", Technician.class);
List<Technician> results = query.getResultList();
List<String> nameList = new ArrayList<String>();
for (Technician item : results)
nameList.add(item.getName());
return nameList;
}
@Override
public ArrayList<String> blabla() throws Exception
{
// TODO Auto-generated method stub
Query q = em.createQuery(
"SELECT technician FROM Technician technician",
Technician.class);
@SuppressWarnings("unchecked")
List<Technician> lst = q.getResultList();
ArrayList<String> nameList = new ArrayList<String>();
for (Technician item : lst)
nameList.add(item.getName());
return nameList;
}
@Override
public int getTechnicianCurrentId()
{
// TODO Auto-generated method stub
return Technician.getIdCount();
}
@Override
public int getCallCurrentId()
{
// TODO Auto-generated method stub
return Call.getIdCount();
}
}
package com.example.backend；
导入java.util.ArrayList；
导入java.util.List；
导入javax.persistence.EntityManager；
导入javax.persistence.EntityManagerFactory；
导入javax.persistence.persistence；
导入javax.persistence.Query；
导入javax.persistence.TypedQuery；
导入com.example.model.Call；
导入com.example.model.CallStatus；
导入com.example.model.SparePart；
导入com.example.model.technology；
导入com.example.model.ThingToDo；
公共类DBbackend实现后端
{
私有EntityManagerFactory emf=null；
私有EntityManager em=null；
私有字符串持久性\u单元\u NAME=“事务可选”；
//
公共DBbackend（）
{
emf=Persistence.createEntityManagerFactory（Persistence\u UNIT\u NAME）；
em=emf.createEntityManager（）；
}
私有void插入（对象obj）引发异常
{
em.getTransaction（）.begin（）；
em.persist（obj）；
尝试
{
em.getTransaction（）.commit（）；
}捕获（例外e）
{
em.clear（）；
投掷e；
}
}
@凌驾
public int getNextCallId（）
{
//TODO自动生成的方法存根
返回0；
}
@凌驾
public void removeCall（int-id）引发异常
{
//TODO自动生成的方法存根
}
@凌驾
公共ArrayList getCallsByTech（技术人员t）引发异常
{
//TODO自动生成的方法存根
返回null；
}
@凌驾
public void updateCall（调用）引发异常
{
//TODO自动生成的方法存根
}
@凌驾
公共作废保存（）
{
//TODO自动生成的方法存根
}
@凌驾
public void addCall（Call Call）引发异常
{
//TODO自动生成的方法存根
}
@凌驾
公共无效addTechnician（Technician Technician）引发异常
{
//TODO自动生成的方法存根
插入（技术员）；
}
@凌驾
公共技术人员getTechnicianByUserName（字符串用户名）引发异常
{
//TODO自动生成的方法存根
返回null；
}
@凌驾
公共调用getCall（int id）引发异常
{
//TODO自动生成的方法存根
返回null；
}
@凌驾
public void addCallToTech（呼叫，技师t）引发异常
{
//TODO自动生成的方法存根
call.setTechnician（t）；
插入（调用）；
}
@凌驾
公共技师findTechByName（字符串名称）引发异常
{
//TODO自动生成的方法存根
查询q=em.createQ
if( variable_could_be_null.equals(variable_known_to_not_be_null) )
if( variable_known_to_not_be_null.equals(variable_could_be_null) )
if(variable_could_be_null!=null)
{
...
}