Spring in action学习

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一：Spring装配bean（IOC注入）

1、构造器注入

对于拥有构造器的bean

构造器参数是基本型：

<bean id="duke"<span style="white-space:pre"></span>class="com.springinaction.springidol.Juggler"><span style="white-space:pre"></span><constructor-arg value="15"/><!--构造器参数，基本类型--></bean>

构造器参数还有其他类对象：

<bean id="poeticDuke"<span style="white-space:pre"></span>class="com.springinaction.springidol.PoeticJuggler"><span style="white-space:pre"></span><constructor-arg value="15"/><span style="white-space:pre"></span><constructor-arg ref="sonnet29"/></bean>

如果没有bean没有构造器：如工厂方法创建bean

<bean id="theStage"<span style="white-space:pre"></span>class="com.springinaction.springidol.Stage"factory-method="getInstance" />

2、注入bean属性 setter注入

<bean id="kenny"<span style="white-space:pre"></span>class="com.springinaction.springidol.Instrumentalist"><span style="white-space:pre"></span><propertyname="song"value="JingleBells"/></bean>

bean含有其他对象的引用：

<bean id="kenny2"<span style="white-space:pre"></span>class="com.springinaction.springidol.Instrumentalist"><span style="white-space:pre"></span><propertyname="song"value="JingleBells"/><span style="white-space:pre"></span><propertyname="instrument"ref="saxophone"/></bean>

注入内部bean:

<bean id="kenny"<span style="white-space:pre"></span>class="com.springinaction.springidol.Instrumentalist"><span style="white-space:pre"></span><propertyname="song"value="JingleBells"/><span style="white-space:pre"></span><propertyname="instrument"><span style="white-space:pre"></span><beanclass="org.springinaction.springidol.Saxophone"/><span style="white-space:pre"></span></property></bean>

装配集合：

<bean id="hank"<span style="white-space:pre"></span>class="com.springinaction.springidol.OneManBand"><span style="white-space:pre"></span><propertyname="instruments"><span style="white-space:pre"></span><list><span style="white-space:pre"></span><ref bean="guitar"/><span style="white-space:pre"></span><ref bean="cymbal"/><span style="white-space:pre"></span><ref bean="harmonica"/><span style="white-space:pre"></span></list><span style="white-space:pre"></span></property></bean>

<bean id="hank"class="com.springinaction.springidol.OneManBand"><propertyname="instruments"><set><ref bean="guitar"/><ref bean="cymbal"/><ref bean="harmonica"/><ref bean="harmonica"/></set></property></bean>

<bean id="hank"class="com.springinaction.springidol.OneManBand"><propertyname="instruments"><map><entry key="GUITAR"value-ref="guitar"/><entry key="CYMBAL"value-ref="cymbal"/><entry key="HARMONICA"value-ref="harmonica"/></map></property></bean>

<bean id="hank"class="com.springinaction.springidol.OneManBand"><propertyname="instruments"><props><prop key="GUITAR">STRUMSTRUMSTRUM</prop><prop key="CYMBAL">CRASHCRASHCRASH</prop><prop key="HARMONICA">HUMHUMHUM</prop></props></property></bean>

注入空值：

<propertyname="someNonNullProperty"><null/></property>

SpEL表达式：

<bean id="carl"class="com.springinaction.springidol.Instrumentalist"><property name="song" value="#{kenny.song}"/><!--song与kenny的song一致--></bean>

有一个SongSelector的bean，有一个selectSong方法，返回一首歌

<propertyname="song" value="#{songSelector.selectSong()}"/>

下面使用?.toUpperCase()代替.toUpperCase()，在带有toUpperCase()时先检查songSelector.selectSong()返回的是否为空，若为空则不会再调用toUpperCase()方法

<property name="song" value="#{songSelector.selectSong()?.toUpperCase()}"/>

当henny.song为null时，则将Greensleeves赋值给song

<property name="song" value="#{kenny.song?:'Greensleeves'}"/>

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