[置顶] 【SSH】注解和非注解的形式配置Spring

一、前言

      在框架学习中，我们学到了很多东西。spring 2.5 的一大增强就是引入了很多注释类，现在您已经可以使用注释配置完成大部分 XML 配置的功能。在这篇文章里，我们将向您讲述使用注释进行 Bean 定义和依赖注入的内容。

二、非注解怎么做？

      在spring 2.5以前，没有注解。不使用注解，我们就需要在spring的applicationContext.xml文件中，添加上要注入的类的实例。原理是当我们需要实例化这个实例，用这个类下面的方法的时候，spring会自动帮我们实例化，从而减少了我们的操作。

      通过下面的代码来表示一下：
      首先由三个类：

      DepartmentDaoImpl ：

public class DepartmentDaoImpl extends HibernateDaoSupport implements DepartmentDao {

    public void saveDepartment(Department department) {
        this.getHibernateTemplate().save(department);
    }
}

      DepartmentServiceImpl ：

public class DepartmentServiceImpl implements DepartmentService {
    private DepartmentDao departmentDao;

    public DepartmentDao getDepartmentDao() {
        return departmentDao;
    }

        public void setDepartmentDao(DepartmentDao departmentDao) 
    {
        this.departmentDao = departmentDao;
    }

    public void saveDepartment(Department department) {
        this.departmentDao.saveDepartment(department);
    }

}

      DepartmentAction ：

public class DepartmentAction extends BaseAction implements ModelDriven<Department> {
    private Department department = new Department();

    public Department getModel() {
        return department;
    }

    private DepartmentService departmentService;

    public DepartmentService getDepartmentService() {
        return departmentService;
    }

    public void setDepartmentService(DepartmentService departmentService) {
        this.departmentService = departmentService;
    }

    /** * 添加操作-2017年5月10日10:48:11 * @return string */
    public String add()  {
        this.departmentService.saveDepartment(department);
        return action2action;
    }
}

      在上面的三个类中，DepartmentServiceImpl 中注入了DepartmentDao，在DepartmentAction 中注入了DepartmentService。

      在spring中，我们需要注入这些：

<?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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">

    <bean id="departmentDao" class="cn.itcast.oa.dao.impl.DepartmentDaoImpl">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>


    <bean id="departmentService" class="cn.itcast.oa.service.impl.DepartmentServiceImpl">
        <property name="departmentDao" ref="departmentDao"/>
    </bean>

    <bean id="departmentAction" class="cn.itcast.oa.struts2.action.DepartmentAction" scope="prototype">
        <property name="departmentService" ref="departmentService"/>
    </bean>
</beans>

      当我们注入的时候，就可以直接使用了。

三、注解怎么做？

      同样的我们需要这三个类，但是需要有一些变动，那就是添加了注解，取消了get和set方法：

      DepartmentDaoImpl ：

@Repository("departmentDao")
public class DepartmentDaoImpl extends BaseDaoImpl<Department> implements DepartmentDao<Department> {


}

      DepartmentServiceImpl ：

@Service("departmentService")
public class DepartmentServiceImpl implements DepartmentService {
    @Resource(name="departmentDao")
    private DepartmentDao departmentDao;


    public void saveDepartment(Department department) {
        this.departmentDao.saveEntry (department);
    }
}

      DepartmentAction :

@Controller("departmentAction")
@Scope("prototype")
public class DepartmentAction extends BaseAction implements ModelDriven<Department> {

    private Department department = new Department();

    public Department getModel() {
        return department;
    }

    @Resource(name="departmentService")
    private DepartmentService departmentService;

    /** * 添加操作-2017年5月10日10:48:11 * @return string */
    public String add()  {

        this.departmentService.saveDepartment(department);
        return action2action;
    }
}

      在上面的三个类中我们通过注解实现了注入，我们分别说明一下注解：

• @Repository(“departmentDao”)

  可以理解为要标志是D层。
  

• @Service(“departmentService”)

  可以理解为要标志是B层的。
  

• @Resource(name=”departmentDao”)

  这个是DepartmentServiceImpl为了注入DepartmentDao而引入的。可以理解为为了注入D层而写的，可以得到D层的示例。
  

• @Controller(“departmentAction”)和@Scope(“prototype”)

  这个可以理解为Action的标志

• @Resource(name=”departmentService”)

  同 @Resource(name=”departmentDao”)，表示注入了DepartmentService。

      当然，通过写了注入，我们需要在spring的ApplicationContext.xml中进行配置。这里要声明的是spring2.5 以上 ，如下：

      在导入类扫描的注解解析器和事务的注解解析器，会自动扫描我们填写了注解的类。

<?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: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/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">
    <!-- 导入类扫描的注解解析器和事务的注解解析器 -->
      <context:component-scan base-package="cn.itcast.oa"></context:component-scan>
      <tx:annotation-driven transaction-manager="transactionManager"/>
      <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
            <property name="sessionFactory">
                <ref bean="sessionFactory"/>
            </property>
      </bean>

      <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="configLocation">
            <value>classpath:hibernate/hibernate.cfg.xml</value>
        </property>
      </bean>

      <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
        <property name="sessionFactory">
            <ref bean="sessionFactory"/>
        </property>
      </bean>

</beans>

四、小结

      通过不同的方法，可以达到相同的目的，这个在我们使用的时候就有不同的效果。第一种不使用注释的，我们每次添加一条线，就需要我们在配置文件中手动添加，而第二种，就需要我们在添加的线上，加入注解就可以了。