spring 杂烩

Spring IoC容器的实例化非常简单，如下面的例子：

Resource resource = new FileSystemResource("beans.xml");
BeanFactory factory = new XmlBeanFactory(resource);


ClassPathResource resource = new ClassPathResource("beans.xml");
BeanFactory factory = new XmlBeanFactory(resource);


ApplicationContext context = new ClassPathXmlApplicationContext(
        new String[] {"applicationContext.xml", "applicationContext-part2.xml"});
// of course, an ApplicationContext is just a BeanFactory
BeanFactory factory = (BeanFactory) context;

在容器内部，这些bean定义由BeanDefinition 对象来表示，该定义将包含以下信息：

从本质上讲，BeanFactory仅仅只是一个维护bean定义以及相互依赖关系的高级工厂接口。通过BeanFactory我们可以访问bean定义。下面的例子创建了一个bean工厂，此工厂将从xml文件中读取bean定义：

InputStream is = new FileInputStream("beans.xml");
BeanFactory factory = new XmlBeanFactory(is);


在<constructor-arg/>或<property/>元素内部还可以使用ref元素。
<ref bean="someBean"/>
<ref local="someBean"/>
<!-- in the child (descendant) context -->
<bean id="accountService"  <-- notice that the name of this bean is the same as the name of the 'parent' bean
      class="org.springframework.aop.framework.ProxyFactoryBean">
      <property name="target">
          <ref parent="accountService"/>  <-- notice how we refer to the parent bean
      </property>
    <!-- insert other configuration and dependencies as required as here -->
</bean>


通过<list/>、<set/>、<map/>及<props/>元素可以定义和设置与Java Collection类型对应List、Set、Map及Properties的值。

<bean id="moreComplexObject" class="example.ComplexObject">
  <!-- results in a setAdminEmails(java.util.Properties) call -->
  <property name="adminEmails">
    <props>
        <prop key="administrator">administrator@somecompany.org</prop>
        <prop key="support">support@somecompany.org</prop>
        <prop key="development">development@somecompany.org</prop>
    </props>
  </property>
  <!-- results in a setSomeList(java.util.List) call -->
  <property name="someList">
    <list>
        <value>a list element followed by a reference</value>
        <ref bean="myDataSource" />
    </list>
  </property>
  <!-- results in a setSomeMap(java.util.Map) call -->
  <property name="someMap">
    <map>
        <entry>
            <key>
                <value>yup an entry</value>
            </key>
            <value>just some string</value>
        </entry>
        <entry>
            <key>
                <value>yup a ref</value>
            </key>
            <ref bean="myDataSource" />
        </entry>
    </map>
  </property>
  <!-- results in a setSomeSet(java.util.Set) call -->
  <property name="someSet">
    <set>
        <value>just some string</value>
        <ref bean="myDataSource" />
    </set>
  </property>
</bean>

注意：map的key或value值，或set的value值不能是以下元素：

bean | ref | idref | list | set | map | props | value | null

这等同于Java代码： exampleBean.setEmail("")。而null值则可以使用<null>元素可用来表示。例如：

<bean class="ExampleBean">
  <property name="email"><null/></property>
</bean>

在XML配置文件中，延迟初始化将通过<bean/>元素中的lazy-init属性来进行控制。例如：
在容器层次中通过在<beans/>元素上使用'default-lazy-init'属性来控制延迟初始化也是可能的


UrlResource 
ClassPathResource 
FileSystemResource 
ServletContextResource 
InputStreamResource 
ByteArrayResource 

实现org.springframework.validation.Validator接口中的两个方法，我们将为对Person类加上校验行为