Jsp 表格不';无法识别数据,processRequests会抛出NullPointerException
我有一个网站,我已经连接到glassfish服务器。我想创建可以在此数据库中添加/删除/编辑/搜索数据的按钮 处理用户代码输入数据的公式:Jsp 表格不';无法识别数据,processRequests会抛出NullPointerException,jsp,jakarta-ee,netbeans,glassfish,Jsp,Jakarta Ee,Netbeans,Glassfish,我有一个网站,我已经连接到glassfish服务器。我想创建可以在此数据库中添加/删除/编辑/搜索数据的按钮 处理用户代码输入数据的公式: <form action="./StudentServlet" method="POST"> <table> <tr> <td>Sensor ID</td> <td><input type="text" na
<form action="./StudentServlet" method="POST">
<table>
<tr>
<td>Sensor ID</td>
<td><input type="text" name="sensorId" value="${sensor.sensorId}" /></td>
</tr>
<tr>
<td>Nazwa</td>
<td><input type="text" name="nazwa" value="${sensor.nazwa}" /></td>
</tr>
<tr>
<td>Opis</td>
<td><input type="text" name="opis" value="${sensor.opis}" /></td>
</tr>
<tr>
<td>Prawa</td>
<td><input type="text" name="prawa" value="${sensor.prawa}" /></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" name="action" value="Add">
<input type="submit" name="action" value="Edit">
<input type="submit" name="action" value="Delete">
<input type="submit" name="action" value="Search">
</td>
</tr>
</table>
</form>
<br>
<table border="1">
<th>ID</th>
<th>Nazwa</th>
<th>Opis</th>
<th>Prawa</th>
<c:forEach items="${allSensors}" var="sensor">
<tr>
<td>${sensor.sensorId}</td>
<td>${sensor.nazwa}</td>
<td>${sensor.opis}</td>
<td>${sensor.prawa}</td>
</tr>
</c:forEach>
</table>
错误日志:
WARNING: StandardWrapperValve[StudentServlet]: PWC1406: Servlet.service() for servlet StudentServlet threw exception
java.lang.NullPointerException
at com.student.controller.StudentServlet.processRequest(StudentServlet.java:37)
at com.student.controller.StudentServlet.doPost(StudentServlet.java:60)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:688)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
我无法查看数据。如果第37行是“studentDao.addSensor(sensor);”
这意味着StudentDaoLocal未正确注入studentDao变量。IDE抱怨EJB或StudentDaoLocal还有一些其他错误?为什么有4个输入具有相同的name属性?这是错误的,servlet中发生错误的第37行是什么?它说第37行是:studentDao.addSensor(sensor);我尝试删除了3个按钮,因此只保留了1个按钮,只有一个属性,但出现了相同的错误。表单中有
sensorId
,但正在Servlet
中读取studentId
。
WARNING: StandardWrapperValve[StudentServlet]: PWC1406: Servlet.service() for servlet StudentServlet threw exception
java.lang.NullPointerException
at com.student.controller.StudentServlet.processRequest(StudentServlet.java:37)
at com.student.controller.StudentServlet.doPost(StudentServlet.java:60)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:688)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)