我对 Spring+Hibernate 非常陌生，并且正在开发一个非常基本的 Web 项目。使用简单的形式，有两个字段用户名和密码。它有一个提交按钮。单击提交时，我应该检查数据库中是否存在用户名和密码。这是我的 AuthenticationService 类
package com.service;
import java.util.List;
import org.hibernate.SessionFactory;
import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.stereotype.Service;
@Service
public class AuthenticateService{
private HibernateTemplate hibernateTemplate;
public void setSessionFactory(SessionFactory sessionFactory)
{
this.hibernateTemplate=new HibernateTemplate(sessionFactory);
}
public boolean verifyUsernameAndPassword(String username,String password)
{
System.out.println("Into the Service Class");
boolean userStatus=false;
try
{
List userObj = hibernateTemplate.find("from user u where u.username=? and u.password=?",username,password);
if(userObj.size()!=0)
{
userStatus=true;
}
}
catch(Exception e)
{
e.printStackTrace();
}
return userStatus;
}
}
这是我的 bean 配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="dataSourceBean" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://127.0.0.1:3306/springmvc"></property>
<property name="username" value="root"></property>
<property name="password" value=""></property>
</bean>
<!-- org.springframework.orm.hibernate3.LocalSessionFactoryBean -->
<bean id="sessionFactoryBean" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSourceBean"></property>
<property name="mappingResources">
<value>com/pojo/user.hbm.xml</value>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<bean id="hibernateTemplateBean" class="org.springframework.orm.hibernate3.HibernateTemplate">
<property name="sessionFactory" ref="sessionFactoryBean"></property>
</bean>
<bean id="authenticateServiceBean" class="com.service.AuthenticateService">
<property name="hibernateTemplate" ref="hibernateTemplateBean"></property>
</bean>
</beans>
这是我的登录控制器：
package com.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
import com.service.AuthenticateService;
@Controller
@RequestMapping("/login.spring")
public class LoginController {
@Autowired
AuthenticateService authenticateService;
@RequestMapping(method= RequestMethod.POST)
public ModelAndView processCredentials(@RequestParam("username")String username ,@RequestParam("password")String password)
{
System.out.println("Inside username"+username + " password"+password);
String message="Invalid Credentials";
if(authenticateService.verifyUsernameAndPassword(username, password)==true)
{
message="Welcome"+username;
}
return new ModelAndView("results","message",message);
}
}
当我运行应用程序时，我得到以下堆栈跟踪：
java.lang.NullPointerException
at com.service.AuthenticateService.verifyUsernameAndPassword(AuthenticateService.java:31)
at com.controller.LoginController.processCredentials(LoginController.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:440)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:428)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:662)
我确信应用程序会进入服务类，因为我已经打印了“服务类内部”。我不知道为什么它给了我一个 NullPointer。