2.2.7  Bean的生命週期

Spring 內的Bean物件從建立到銷燬，可控點很多。

2.2.8 <bean>的id與name 屬性

name對格式沒有限制，id有

2.3 基於XML的DI

2.3.1 注入分類

設值注入：

       基本屬性用 value

       物件對應的屬性用 ref

	<bean id="myStudent" class="com.bjpowernode.di01.Student">
		<property name="name" value="張三"/>
		<property name="age" value="23"/>
		<property name="school" ref="mySchool"/>
	</bean>
 

構造注入：

       少用

	<bean id="myStudent" class="com.bjpowernode.di02.Student">
		<constructor-arg name="name" value="李四"/>
		<constructor-arg name="age" value="24"/>
		<constructor-arg name="school" ref="mySchool"/>
		<!--  
		<constructor-arg index="0" value="李四"/>
		<constructor-arg index="1" value="24"/>
		<constructor-arg index="2" ref="mySchool"/>
		-->
		<!--
		<constructor-arg value="李四"/>
		<constructor-arg value="24"/>
		<constructor-arg ref="mySchool"/>
		-->
	</bean>
 

2.3.3 集合屬性注入

properties 的鍵值對均為String型別，map自定義

①

<?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.xsd">
        
	<bean id="mySchool" class="com.bjpowernode.di05.School">
		<property name="name" value="清華大學"/>
	</bean>

	<bean id="mySchool2" class="com.bjpowernode.di05.School">
		<property name="name" value="北京大學"/>
	</bean>
	
	<bean id="mySome" class="com.bjpowernode.di05.Some">
		<property name="schools">
			<array>
				<ref bean="mySchool"/>
				<ref bean="mySchool2"/>
			</array>
		</property>
		<property name="myStr">
			<array>
				<value>中國</value>
				<value>北京</value>
			</array>
		</property>
		<property name="myList">
			<list>
				<value>海淀</value>
				<value>六道口</value>
			</list>
		</property>
		<property name="mySet">
			<set>
				<value>中國農業大學</value>
				<value>男生公寓</value>
			</set>
		</property>
		<property name="myMap">
			<map>
				<entry key="mobile" value="1234567"/>
				<entry key="QQ" value="7654321"/>
			</map>
		</property>
		<property name="myProperties">
			<props>
				<prop key="education">大學</prop>
				<prop key="gender">男</prop>
			</props>
		</property>
		
	</bean>
	
</beans>
 

②：對於set，array，list等集合型別的屬性，資料注入時可採用簡寫的形式<property name="" value=", , ,">

<?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.xsd">
        
	<bean id="mySchool" class="com.bjpowernode.di06.School">
		<property name="name" value="清華大學"/>
	</bean>

	<bean id="mySchool2" class="com.bjpowernode.di06.School">
		<property name="name" value="北京大學"/>
	</bean>
	
	<bean id="mySome" class="com.bjpowernode.di06.Some">
		<property name="schools">
			<array>
				<ref bean="mySchool"/>
				<ref bean="mySchool2"/>
			</array>
		</property>
		
		<property name="myStr" value="中國,北京"/>

		<property name="myList" value="海淀,六道口"/>

		<property name="mySet" value="中國農業大學,男生公寓">

		</property>
		<property name="myMap">
			<map>
				<entry key="mobile" value="1234567"/>
				<entry key="QQ" value="7654321"/>
			</map>
		</property>
		<property name="myProperties">
			<props>
				<prop key="education">大學</prop>
				<prop key="gender">男</prop>
			</props>
		</property>
		
	</bean>
	
</beans>

2.3.4 對於域屬性的自動化注入

autowire="byName" 會從容器中查詢與實體類的域屬性同名的Bean的id，並將該Bean物件自動注入給該實體類的域屬性。

<?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.xsd">
        
	<bean id="school" class="com.bjpowernode.di07.School">
		<property name="name" value="清華大學"/>
	</bean>
	
	<!-- 註冊Student
		autowire="byName" 會從容器中查詢與實體類的域屬性同名的Bean的id，
		並將該Bean物件自動注入給該實體類的域屬性。	
	 -->
	<bean id="myStudent" class="com.bjpowernode.di07.Student" autowire="byName"> 
		<property name="name" value="張三"/>
		<property name="age" value="23"/>
	</bean>
	
</beans>

 autowire="byType" 會從容器中將與實體類中域屬性型別具有is-a關係的bean找到，並將該bean自動注入到域屬性。

（因為可向上轉型）

 同一個類的兩個物件和具有is-a關係的多個類的多個物件均不可。

<?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.xsd">
        
	<bean id="mySchool" class="com.bjpowernode.di08.School">
		<property name="name" value="清華大學"/>
	</bean>
    <!--
	<bean id="mySchool2" class="com.bjpowernode.di08.PrimarySchool">
		<property name="address" value="海淀區"/>
	</bean>
    -->
	<!-- 註冊Student
		autowire="byType" 會從容器中查詢與實體類的域屬性型別具有is-a關係的Bean，
		並將該Bean物件自動注入給該實體類的域屬性。	
	 -->
	<bean id="myStudent" class="com.bjpowernode.di08.Student" autowire="byType"> 
		<property name="name" value="張三"/>
		<property name="age" value="23"/>
	</bean>
	
</beans>

2.3.5 SPEL注入

可以使用靜態方法，

可以訪問其他Bean的屬性

直接計算表示式

呼叫其他Bean的方法

<?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.xsd">
        
	<bean id="myPerson" class="com.bjpowernode.di08.Person">
		<property name="pname" value="李四"/>
		<property name="page" value="#{T(java.lang.Math).random()*50}"/>
	</bean>
	
	<bean id="myStudent" class="com.bjpowernode.di08.Student"> 
		<property name="name" value="#{myPerson.pname}"/>
		<property name="age" value="#{myPerson.computeAge()}"/>
	</bean>
	
</beans>