我在spring Dao中遇到错误，而数据插入:警告: servlet spring抛出异常java.lang.NullPointerException
我在spring Dao中遇到错误，而数据插入:警告: servlet spring抛出异常java.lang.NullPointerException
提问于 2018-08-09 15:41:59
我是spring的新手，刚开始学习将数据插入到oracle数据库中，我创建了一个web项目，只看了很少的教程，并创建了所有必要的步骤，但在运行过程中，我得到了下面提到的这个错误，感谢您的帮助。
Spring-servlet.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd ">
<context:annotation-config />
<context:component-scan base-package="com.x"/>
<!-- Getting Database properties -->
<context:property-placeholder location="classpath:connectDb.properties" />
<bean class="org.springframework.jdbc.datasource.DriverManagerDataSource"
id="dataSource">
<property name="driverClassName" value="${database.driver}"></property>
<property name="url" value="${database.url}"></property>
<property name="username" value="${database.user}"></property>
<property name="password" value="${database.password}"></property>
</bean>
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/"/>
<property name="suffix" value=".jsp"/>
</bean>
</beans>web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>nowpro1</display-name>
<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>spring</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>AnotherFormController.java
package com.x;
import com.x.dao.EmpDao;
import com.x.model.Emp;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
public class AnotherFormController {
//public EmpDao dao;
@RequestMapping("/")
public ModelAndView homeMethod() {
// System.out.println("Hello World");
String Mess = "Another Abstract Controller Test";
ModelAndView modelAndView = new ModelAndView("index");
modelAndView.addObject("message", Mess);
return modelAndView;
}
@RequestMapping(value="/welcome", method=RequestMethod.POST)
public ModelAndView CtrlMethod(@ModelAttribute("employee1") Emp employee1) {
ModelAndView model = new ModelAndView("hellopage");
EmpDao dao = new EmpDao();
dao.insertData(new Emp(104,"Jenish","jenish@gmail.com","9445807204"));
System.out.println(employee1.getEname());
return model;
}
}Emp.java
package com.x.model;
public class Emp {
private int Eid;
private String Ename;
private String Mobile;
private String Email;
public int getEid() {
return Eid;
}
public void setEid(int Eid) {
this.Eid = Eid;
}
public String getEname() {
return Ename;
}
public void setEname(String Ename) {
this.Ename = Ename;
}
public String getMobile() {
return Mobile;
}
public void setMobile(String Mobile) {
this.Mobile = Mobile;
}
public String getEmail() {
return Email;
}
public void setEmail(String Email) {
this.Email = Email;
}
public Emp(){
}
public Emp(int Eid,String Ename,String Mobile,String Email) {
setEid(Eid);
setEname(Ename);
setMobile(Mobile);
setEmail(Email);
}
}EmpDao.java
package com.x.dao;
import com.x.model.Emp;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
public class EmpDao {
private DataSource dataSource;
private JdbcTemplate jdbcTemplate;
public JdbcTemplate getJdbcTemplate() {
return jdbcTemplate;
}
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
public DataSource getDataSource() {
return dataSource;
}
@Autowired
public void setDataSource(DataSource dataSource) {
this.jdbcTemplate = new JdbcTemplate(dataSource);
}
public void insertData(Emp emp) {
String sql = "insert into Emp (Eid,Ename,Mobile,Email) values(?,?,?,?)";
jdbcTemplate.update(sql, new Object[] {emp.getEid(),emp.getEname(),emp.getMobile(),emp.getEmail()});
}
}我的错误
Warning: StandardWrapperValve[spring]: Servlet.service() for servlet spring threw exception
java.lang.NullPointerException
at com.x.dao.EmpDao.insertData(EmpDao.java:39)
at com.x.AnotherFormController.CtrlMethod(AnotherFormController.java:27)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:177)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:416)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:283)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:283)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:200)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:132)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:111)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:536)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571)
at java.lang.Thread.run(Thread.java:748)回答 1
Stack Overflow用户
回答已采纳
发布于 2018-08-09 18:56:31
NullPointerException是一个明显的例外。该异常似乎与Spring Dao无关。在insertData方法的开头设置断点。我认为emp是null，所以当你调用Emp字段的getter方法时，你会得到NullPointerException。
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原文链接：
https://stackoverflow.com/questions/51761389
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