数据插入时我在spring dao中出错：警告：servlet spring抛出异常java.lang.NullPointerException

时间：2018-08-09 07:41:59

标签： spring spring-mvc spring-data-jpa spring-jdbc

我刚接触弹簧，只是学习将数据插入到oracle数据库中。我创建了一个Web项目，只看了几本教程，并创建了所有必需的步骤，但是在运行时，我得到了下面的错误提示，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)

1 个答案:

答案 0 :(得分：0)

NullPointerException是一个明显的例外。似乎该异常与Spring Dao无关。在insertData方法的开始处设置断点。我认为emp是null，所以当您调用Emp的字段的获取方法时，您会得到NullPointerException。

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