我正在尝试使用 wicket + hibernate + spring 编写 Web 应用程序。和所有人一样，我想使用 @Autowired 注释。首先，这是我的 applicationContext.xml：
<beans default-autowire="autodetect"
xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
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
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<context:annotation-config/>
<bean id="placeholderConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="false"/>
<property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE"/>
<property name="ignoreResourceNotFound" value="false"/>
<property name="locations">
<list>
<value>classpath*:/application.properties</value>
</list>
</property>
</bean>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
//connection...
</bean>
<tx:annotation-driven transaction-manager="txManager"/>
<!-- setup transaction manager -->
<bean id="txManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory">
<ref bean="sessionFactory"/>
</property>
</bean>
<!-- hibernate session factory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
//some hibernate stuff
</bean>
//wicket app bean
<bean id="wicketApplication" class="com.team.wicket.ShopApp" scope="singleton"/>
//DAO beans
<bean id="userDAO" class="com.team.wicket.daoImpl.UserDAOImpl" scope="singleton"/>
<bean id="contactDAO" class="com.team.wicket.daoImpl.ContactDAOImpl" scope="singleton"/>
这是web.xml：
<display-name>wicket-spring-hibernate</display-name>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<filter>
<filter-name>opensessioninview</filter-name>
<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
</filter>
<filter>
<filter-name>wicket-spring-hibernate</filter-name>
<filter-class>org.apache.wicket.protocol.http.WicketFilter</filter-class>
<init-param>
<param-name>applicationFactoryClassName</param-name>
<param-value>org.apache.wicket.spring.SpringWebApplicationFactory</param-value>
</init-param>
<init-param>
<param-name>applicationClassName</param-name>
<param-value>com.mycompany.WicketApplication</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>opensessioninview</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>wicket-spring-hibernate</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
实际上，我只需要将 @Autowired 与 userDAO 和 contactDAO bean 一起使用。UserDAOImpl 和 ContactDAOImpl 的代码以@Service 注解开头：
@Service
public class ContactDAOImpl implements ContactDAO {
....
public ContactDAOImpl() {
System.out.println("contactDAO created");
}
@Service
public class UserDAOImpl implements UserDAO {
...
public UserDAOImpl() {
System.out.println("UserDAO created");
}
如您所见，我已将 System.out 添加到类的默认构造函数中，因为我想确保 spring 创建 bean。每次我启动应用程序时它都会创建 bean，所以问题一定出在自动装配上。最后是自动装配失败的类：
public class UserSession extends AuthenticatedWebSession {
@Autowired
@Qualifier("userDAO")
private UserDAO userDAO;
private User user;
public UserSession(Request request) {
super(request);
}
@Override
public boolean authenticate(String username, String password) {
User user = userDAO.getUser(username, password);
if (user != null) {
setUser(user);
return true;
}
return false;
}
@Override
public Roles getRoles() {
Roles roles = new Roles();
if (isSignedIn()) {
roles.add(Roles.USER);
}
return roles;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
当 authenticate() 尝试调用 getUser(...) 时，它会给出 NullPointerException。通过调试，我知道 UserDAO 没有初始化（它只是空），我也知道 Spring 创建了 UserDAO 和 ContactDAO bean。那么我做错了什么？谢谢。