spring - 自动装配的对象返回 null

Question

可能重复：
Servlet 中的 Spring @Autowired 使用 Servlet
配置 Spring Ioc

我想将 dao 注入 servlet，但它返回为 null。

应用程序上下文.xml

<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" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-2.5.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

    <!-- Enable @Required @Autowired @PreDestroy @PostConstruct @Resource -->
    <context:annotation-config />

    <!-- Scan class file in class path for annotated component -> @Component, @Repository, @Service, and @Controller  -->
    <context:component-scan base-package="com.breeze.bis.core.service.jdbcTemplate" />

    <!-- Enable load time weaving for @Configurable -->
    <context:load-time-weaver aspectj-weaving="autodetect" />

    <!--  -->
    <tx:annotation-driven proxy-target-class="false" transaction-manager="transactionManager"/>

    <!-- ==================================================================================================== -->

    <!-- Alternate method to enable @Autowired -->
    <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/vbossdb" />
        <property name="driverClass" value="com.mysql.jdbc.Driver" />
        <property name="user" value="root" />
        <property name="password" value="root" />
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <constructor-arg type="javax.sql.DataSource" ref="dataSource"></constructor-arg>
    </bean>

    <bean id="genericDaoImpl" class="com.breeze.bis.core.service.jdbcTemplate.GenericDAOImpl">
        <property name="jdbcDao" ref="jdbcTemplate"></property> 
    </bean>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property> 
    </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" 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_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>BISDAO</display-name>
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>WEB-INF/applicationContext.xml</param-value>
  </context-param>
  <listener>
    <display-name>contextLoaderListener</display-name>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
</webapp>

DAO.java

@Component 
@Transactional(propagation=Propagation.REQUIRED, isolation=Isolation.DEFAULT, rollbackFor={Exception.class, SQLException.class}, timeout=9999)
public class GenericDAOImpl implements GenericDAO {

    private JdbcTemplate jdbcDao;
    /**
     * 
     */
    public GenericDAOImpl() {

    }

    /**
     * @return the jdbcDao
     */
    public JdbcTemplate getJdbcDao() {
        return jdbcDao;
    }

    /**
     * @param jdbcDao the jdbcDao to set
     */
    public void setJdbcDao(JdbcTemplate jdbcDao) {
        this.jdbcDao = jdbcDao;
    }

    /* (non-Javadoc)
     * @see com.breeze.bis.core.service.jdbcTemplate.GenericDAO#createObject(java.lang.String, java.lang.Object)
     */
    @Override
    @SuppressWarnings("unchecked")
    public int createObject(String sql,  Map<Integer, Object> paramMap) {

        boolean hasResult = true, hasKey = true;

        IStatementExecutor stmtExecutor = new UpdateStatementExecutor(hasKey);
        IExtractor integerExtr = new IntegerExtractor(null, hasResult);

        GenericDatabaseExecutor executor = new GenericDatabaseExecutor(stmtExecutor, integerExtr);
        GenericPreparedStatementCreator stmtCreator = new GenericPreparedStatementCreator(hasKey, sql, paramMap);

        GenericPreparedStatementCallback stmtCallback = new GenericPreparedStatementCallback(executor);

        return (Integer) this.jdbcDao.execute(stmtCreator, stmtCallback);   
    }

}

Servlet.java

@Configurable
public class GenericServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    @Autowired
    GenericDAO dao;
}

请帮忙。

谢谢。