Question

我正在尝试使用spring hibernate和struts 2。应用程序已成功部署。但是在尝试访问spring bean时我得到NullPointerException。以下是代码UsersBo是一个类

@Autowired
private UsersBo ubo;

public void setUbo(UsersBo ubo) {
    this.ubo = ubo;
}

public UsersBo getUbo() {
    return ubo;
}

我查了一下，发现udo是空的。以下是配置文件。

<?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-2.5.xsd">

<!-- Hibernate session factory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean" scope="singleton">

    <property name="dataSource">
      <ref bean="dataSource"/>
    </property>

    <property name="annotatedClasses">
    <list>
        <value>com.riteshsangwan.ossoc.entities.Users</value>
        <value>com.riteshsangwan.ossoc.entities.Files</value>
    </list>
    </property>

    <property name="hibernateProperties">
       <props>
         <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>
         <prop key="hibernate.show_sql">true</prop>
         <prop key="hibernate.cache.use_second_level_cache">true</prop>
         <prop key="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</prop>
         <prop key="hibernate.cache.use_query_cache">true</prop>
         <prop key="cache.provider_class">net.sf.ehcache.hibernate.EhCacheProvider</prop>
       </props>
    </property>

    </bean>
</beans>

DataSource bean

<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-2.5.xsd">

  <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/ossoc;create=true" />
    <property name="username" value="root" />
    <property name="password" value="deflection" />
  </bean>

</beans>

的applicationContext.xml

<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-2.5.xsd">

    <!-- Database Configuration -->
    <import resource="DataSource.xml"/>
    <import resource="HibernateSessionFactory.xml"/>

    <!-- Beans Declaration -->
    <import resource="UsersBean.xml"/>

</beans>

的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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
        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>ossoc</display-name>
        <welcome-file-list>
            <welcome-file>/index.jsp</welcome-file>
        </welcome-file-list>
        <!-- Filter Start -->
        <filter>
            <filter-name>struts2</filter-name>
            <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
        </filter>


        <!-- Filter End -->



        <!-- Filter Mapping Start -->
        <filter-mapping>
            <filter-name>struts2</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>


        <!-- Filter Mapping End -->

        <!-- Listener Start -->

<!-- Spring Start -->
        <listener>
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
        </listener>
</web-app>

用户bean

<?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-2.5.xsd">

    <bean id="loginAction" class="com.riteshsangwan.ossoc.actions.LoginAction">
        <property name="ubo" ref="usersBo" />   
    </bean>

    <bean id="usersBo" class="com.riteshsangwan.ossoc.business.UsersBoImpl" >
        <property name="udao" ref="usersDAOImpl" />
    </bean>

    <bean id="usersDAOImpl" class="com.riteshsangwan.ossoc.business.UsersDAOImpl" >
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

</beans>

我在课程定义

上面添加了@Repository注释

Answer 1

要启用@Autowired注释，您必须在Spring配置文件（Users bean xml文件）中添加<context:annotation-config />。您还必须添加上下文命名空间

xmlns:context="http://www.springframework.org/schema/context"

所以，你的xml将是

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

    <context:annotation-config />

    <bean id="loginAction" class="com.riteshsangwan.ossoc.actions.LoginAction">
        <property name="ubo" ref="usersBo" />   
    </bean>

    <bean id="usersBo" class="com.riteshsangwan.ossoc.business.UsersBoImpl" >
        <property name="udao" ref="usersDAOImpl" />
    </bean>

    <bean id="usersDAOImpl" class="com.riteshsangwan.ossoc.business.UsersDAOImpl" >
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

</beans>

希望这有帮助！我还看到setter和getters方法应遵循Java命名约定。因此，spring可以在依赖注入期间找到合适的setter。请更改/遵循代码中的Java命名约定。

Struts + spring + hibernate Spring bean NullPointerException

1 个答案: