我正在使用 Spring、Hibernate 和 PostgreSQL。我想将对象保存在来自 jsp 页面的数据库中。但它会抛出 NullPointerException。我使用序列生成器进行自动递增，并在 PostgreSQL 中创建了一个名为 emp_id_seq 的序列。我打印发现问题的对象，它显示
员工 [id=null, firstName=vara, lastName=raj, address=abc, dob=Tue Jun 13 00:00:00 IST 2017, nic=154184125V, email=abc@xyz.com, companyId =1, departmentId=4]
错误
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause
java.lang.NullPointerException
org.postgresql.core.CachedQueryCreateAction.create(CachedQueryCreateAction.java:39)
org.postgresql.core.CachedQueryCreateAction.create(CachedQueryCreateAction.java:17)
org.postgresql.util.LruCache.borrow(LruCache.java:115)
org.postgresql.core.QueryExecutorBase.borrowQuery(QueryExecutorBase.java:266)
org.postgresql.jdbc.PgConnection.borrowQuery(PgConnection.java:143)
org.postgresql.jdbc.PgPreparedStatement.<init>(PgPreparedStatement.java:88)
org.postgresql.jdbc.PgConnection.prepareStatement(PgConnection.java:1256)
org.postgresql.jdbc.PgConnection.prepareStatement(PgConnection.java:1622)
org.postgresql.jdbc.PgConnection.prepareStatement(PgConnection.java:415)
org.apache.commons.dbcp2.DelegatingConnection.prepareStatement(DelegatingConnection.java:293)
org.apache.commons.dbcp2.DelegatingConnection.prepareStatement(DelegatingConnection.java:293)
org.hibernate.engine.jdbc.internal.StatementPreparerImpl$1.doPrepare(StatementPreparerImpl.java:87)
org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareStatement(StatementPreparerImpl.java:72)
org.hibernate.id.SequenceGenerator.generateHolder(SequenceGenerator.java:114)
org.hibernate.id.SequenceHiLoGenerator.generate(SequenceHiLoGenerator.java:62)
org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:101)
org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:97)
org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:648)
org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:640)
org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:635)
com.pulseBeatMaster.dao.impl.EmployeeDaoImpl.saveOrUpdate(EmployeeDaoImpl.java:43)
com.pulseBeatMaster.dao.impl.EmployeeDaoImpl$$FastClassBySpringCGLIB$$dadeda1c.invoke(<generated>)
org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)
com.pulseBeatMaster.dao.impl.EmployeeDaoImpl$$EnhancerBySpringCGLIB$$a0d1e9e8.saveOrUpdate(<generated>)
com.pulseBeatMaster.service.impl.EmployeeServiceImpl.saveOrUpdate(EmployeeServiceImpl.java:34)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333)
org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
com.sun.proxy.$Proxy64.saveOrUpdate(Unknown Source)
com.pulseBeatMaster.controller.EmployeeController.saveUser(EmployeeController.java:60)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
模型类
@Entity
@Table(name = "employee", schema = "schpulsebeat")
public class Employee {
private Integer id;
private String firstName;
private String lastName;
private String address;
private Date dob;
private String nic;
private String email;
private Integer companyId;
private Integer departmentId;
public Employee() {
super();
}
public Employee(Integer id, String firstName, String lastName, String address, Date dob, String nic, String email,
Integer companyId, Integer departmentId) {
super();
this.id = id;
this.firstName = firstName;
this.lastName = lastName;
this.address = address;
this.dob = dob;
this.nic = nic;
this.email = email;
this.companyId = companyId;
this.departmentId = departmentId;
}
@Id
//schpulsebeat is a schema. employee_id_seq is created as sequence in postgresql.
@SequenceGenerator(name="employee_id_seq",sequenceName="schpulsebeat.employee_id_seq",allocationSize=1)
@GeneratedValue(strategy=GenerationType.SEQUENCE,generator="employee_id_seq")
@Column(name="employee_id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
@Column(name="first_name")
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
@Column(name="last_name")
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Column(name="address")
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Column(name="dob")
@DateTimeFormat(pattern = "yyyy-MM-dd")
public Date getDob() {
return dob;
}
public void setDob(Date dob) {
this.dob = dob;
}
@Column(name="nic")
public String getNic() {
return nic;
}
public void setNic(String nic) {
this.nic = nic;
}
@Column(name="email")
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Column(name="company_id", nullable=true)
public Integer getCompanyId() {
return companyId;
}
public void setCompanyId(Integer companyId) {
this.companyId = companyId;
}
@Column(name="department_id", nullable=true)
public Integer getDepartmentId() {
return departmentId;
}
public void setDepartmentId(Integer departmentId) {
this.departmentId = departmentId;
}
@Override
public String toString() {
return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", address=" + address
+ ", dob=" + dob + ", nic=" + nic + ", email=" + email + ", companyId=" + companyId + ", departmentId="
+ departmentId + "]";
}
}
Controller
@RequestMapping(value = "/saveEmployee", method = RequestMethod.POST)
public ModelAndView saveUser(@ModelAttribute("employeeForm") Employee employee) {
//System.out.println("object data"+employee.toString());
employeeService.saveOrUpdate(employee);
return new ModelAndView("redirect:/");
}
jsp 页面(为了方便删除了所有 css 样式)
<spring:url value="/saveEmployee" var="saveURL"></spring:url>
<form:form action="${saveURL}" method="POST" modelAttribute="employeeForm">
<form:hidden path="id" />
<form:select class="form-control" name="companyId">
<form:option value="1">Lunah Labs</option>
<form:option value="2">XYZ conf</option>
<form:option value="3">New Tech Lead</option>
<form:option value="4">FINWIN</option>
</form:select>
<form:select class="form-control" name="departmentId">
<form:option value="4">CIS</option>
<form:option value="5">Tech</option>
<form:option value="6">Electronic</option>
<form:option value="7">Event</option>
</form:select>
<form:input path="firstName"/>
<form:input path="lastName" />
<form:input path="address" />
<form:input path="dob" type="date" />
<form:input path="nic" />
<form:input path="email" />
<button type="submit" >Submit</button>
</form:form>
我很担心
1)dob字段
2)生成的id
最佳答案
请给出EmployeeDaoImpl.java类的剩余代码。主要异常发生在第 43 行的 EmployeeDaoImpl.java 类中。
关于Spring 和 PostgreSQL 抛出 java.lang.NullPointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44505661/