java - Springs3 Hibernate3注解配置

Question

我正在尝试为 Hibernate3 注释配置 springs3。我收到以下错误。我怀疑了我的申请。它在 getData() 中创建 User 对象时给出此异常。

异常(exception):

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

    java.lang.NullPointerException
com.controller.userDAO.getdata(userDAO.java:32)
com.controller.MyController.userDetail(MyController.java:32)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:606)
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

这是我的 application-context.xml

    <bean id="DataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
      <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
      <property name="url" value="jdbc:mysql://localhost:3306/test"/>
      <property name="username" value="root"/>
      <property name="password" value=""/>
    </bean>

   <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
      <property name="DataSource" ref="DataSource"/>
      <property name="packagesToScan" value="com.hibernate.models" />
      <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
        </props>
      </property>
   </bean>

DAO:

@Repository
 public class userDAO {

 @Autowired
 private SessionFactory sessionFactory;

 public SessionFactory getSession() {
    return sessionFactory;
 }

 public void setSession(SessionFactory session) {
    this.sessionFactory = session;
 }

 @Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)
 public int getdata() {
    String hql = "select count(*) from User";
    User u = (User) getSession().openSession().createQuery(hql).uniqueResult();
    return 1;
 }
}

Controller :

@Controller 
public class MyController {

@RequestMapping(value = "/{x}/hi", params = {"a"})
public ModelAndView add(@RequestParam(value = "a") int na, @PathVariable int x) {
    System.out.println("print in console");
    ModelAndView mv = new ModelAndView("demo", "message", "Add method called for na and x :" + na + "+" + na + "=" + (na + na + x));
    System.out.println("obj created");
    return mv;
}

@RequestMapping("/user")
public ModelAndView userDetail() {
    userDAO u = new userDAO();
    int x;
    x = u.getdata();
    ModelAndView mv = new ModelAndView("demo", "message", "rows: "+x);
    return mv;
}
}

用户表的用户 bean:

@Entity
@Table(name="user",catalog="test")
 public class User  implements java.io.Serializable {

 private Integer id;
 private String name;
 private int mobile;

public User() {
}

public User(String name, int mobile) {
   this.name = name;
   this.mobile = mobile;
}

 @Id @GeneratedValue(strategy=IDENTITY)

@Column(name="id", unique=true, nullable=false)
public Integer getId() {
    return this.id;
}

public void setId(Integer id) {
    this.id = id;
}

@Column(name="name", nullable=false, length=20)
public String getName() {
    return this.name;
}

public void setName(String name) {
    this.name = name;
}

@Column(name="mobile", nullable=false)
public int getMobile() {
    return this.mobile;
}

public void setMobile(int mobile) {
    this.mobile = mobile;
}

}

调度程序-servlet.xml:

 <!-- Scan only for @Controllers -->
<context:component-scan base-package="com.controller" use-default-filters="false" >
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller" />
</context:component-scan>
<mvc:annotation-driven />


<bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
        <props>
            <prop key="index">indexController</prop>
        </props>
    </property>
</bean>

<bean id="viewResolver"
      class="org.springframework.web.servlet.view.InternalResourceViewResolver"
      p:prefix="/WEB-INF/jsp/"
      p:suffix=".jsp" />

<!--
The index controller.
-->
<bean name="indexController"
      class="org.springframework.web.servlet.mvc.ParameterizableViewController"
      p:viewName="index" />

使用 Autowired 注释在 Controller 中注释用户 dao 对象后，会出现以下异常(UserDao 和 Controller 位于不同的包中):

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping#0' defined in ServletContext resource [/WEB-INF/dispatcher-servlet.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.dao.userDAO com.controller.MyController.u; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.dao.userDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)


org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.dao.userDAO com.controller.MyController.u; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.dao.userDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)



org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.dao.userDAO com.controller.MyController.u; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.dao.userDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:506)
org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)



org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.dao.userDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:924)
org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:793)
org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707)
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478)
org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)

Answer 1

Spring只能处理它创建的对象。它无法将其他 bean 注入(inject)到它不管理的实例中。

这就是你在这里所做的

userDAO u = new userDAO();

你自己创建它，所以Spring对此一无所知，也不会注入(inject)这个字段

@Autowired
private SessionFactory sessionFactory;

相反，将 userDao bean Autowiring 到您的 @Controller 类中。

@Autowired
private userDao userDao;

并使用它。