Spring - IoC(4): p-namespace & c-namespace

p 命名空间

p 命名空间允许你使用 bean 元素的属性而不是 <property/>子元素来描述 Bean 实例的属性值。从 Spring2.0 开始，Spring 支持基于 XML Schema 的方式来简化配置文件。beans 元素的结构定义在一个 XML Schema 文档中。但是，p 命名空间没有定义在 XSD 文件中，而是直接存在与 Spring 内核中。使用 p 命名空间时，只需要在配置文件根元素 beans 引入 xmlns:p="http://www.springframework.org/schema/p"。 

p 命名空间配置的示例：

<?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:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="
     http://www.springframework.org/schema/beans 
     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
    
    <bean id="magicWand" class="com.huey.dream.bean.Weapon"
        p:type="Magic Wand"
        p:weightKg="9.5" />
    
    <bean id="magician" class="com.huey.dream.bean.GameCharacter"
        p:type="Magician"
        p:level="10"
        p:weapon-ref="magicWand" />
    
</beans>

上述的配置与如下的配置等价：

<?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-3.0.xsd">

    <bean id="magicWand" class="com.huey.dream.bean.Weapon">
        <property name="type" value="Magic Wand" />
        <property name="weightKg" value="9.5" />
    </bean>
    
    <bean id="magician" class="com.huey.dream.bean.GameCharacter">
        <property name="type" value="Magician" />
        <property name="level" value="10" />
        <property name="weapon" ref="magicWand" />
    </bean>

</beans>

 

c 命名空间

c 命名空间 与 p 命名空间用法类似，不同是 p 命名空间作用于属性注入，而 c 命名空间作用于构造注入。

p 命名空间配置的示例：

<?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:c="http://www.springframework.org/schema/c"
    xsi:schemaLocation="
     http://www.springframework.org/schema/beans 
     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean id="magicWand" class="com.huey.dream.bean.Weapon"
        c:type="Magic Wand"
        c:weightKg="9.5" />
    
    <bean id="magician" class="com.huey.dream.bean.GameCharacter"
        c:type="Magician"
        c:level="10"
        c:weapon-ref="magicWand" />

</beans>

上述的配置与如下的配置等价：

<?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-3.0.xsd">

    <bean id="magicWand" class="com.huey.dream.bean.Weapon">
        <constructor-arg name="type" value="Magic Wand" />
        <constructor-arg name="weightKg" value="9.5" />
    </bean>
    
    <bean id="magician" class="com.huey.dream.bean.GameCharacter">
        <constructor-arg name="type" value="Magician" />
        <constructor-arg name="level" value="10" />
        <constructor-arg name="weapon" ref="magicWand" />
    </bean>

</beans>