spring提供了filed的值注入和method的返回值注入。
1、Field值的注入
filed值注入需要使用org.springframework.beans.factory.config.FieldRetrievingFactoryBean來(lái)獲取類的靜態(tài)變量。
例如，我們通常在接口中定義常量：
view plaincopy to clipboardprint?package com.baobaotao.fb;
public interface CarBrandType {
String HONG_QI = "紅旗";
String JI_LI = "吉利";
}
package com.baobaotao.fb;
public interface CarBrandType {
String HONG_QI = "紅旗";
String JI_LI = "吉利";
}
下面利用FieldRetrievingFactoryBean獲取CarBandType接口中定義的常量，并注入到某個(gè)bean的屬性中：
view plaincopy to clipboardprint?<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand" ref="hongQi"/>
</bean>
<bean id="hongQi" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean"
<property name="staticField" value="com.baobaotao.fb.CarBrandType.HONG_QI"/>
</bean>
<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand" ref="hongQi"/>
</bean>
<bean id="hongQi" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean"
<property name="staticField" value="com.baobaotao.fb.CarBrandType.HONG_QI"/>
</bean>
Spring還允許用戶用常量的全限定名作為FieldRetrievingFactoryBean的id，其效果和通過(guò)配置staticField屬性是一樣的：
view plaincopy to clipboardprint?<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand" ref="com.baobaotao.fb.CarBrandType.HONG_QI"/>
</bean>
<bean id="com.baobaotao.fb.CarBrandType.HONG_QI" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean" />
<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand" ref="com.baobaotao.fb.CarBrandType.HONG_QI"/>
</bean>
<bean id="com.baobaotao.fb.CarBrandType.HONG_QI" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean" />
當(dāng)然，也可以直接將FieldRetrievingFactoryBean以內(nèi)置bean的方式對(duì)brand屬性進(jìn)行賦值，這樣在配置上更緊湊一些：
view plaincopy to clipboardprint?<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand">
<bean id="com.baobaotao.fb.CarBrandType.HONG_QI" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean">
</bean>
</property>
</bean>
<bean id="car" class="com.baobaotao.fb.Car">
<property name="brand">
<bean id="com.baobaotao.fb.CarBrandType.HONG_QI" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean">
</bean>
</property>
</bean>
2、Method返回值的注入
Method返回值的注入需要使用MethodInvokingFactoryBean來(lái)完成。
在xml配置中，需要設(shè)定targetObject和targetMethod來(lái)指定目標(biāo)bean和方法。如果使用靜態(tài)方法，則需要指定targetClass和targetMethod
配置文件如下：
view plaincopy to clipboardprint?<bean id="bdog" class="com.baobaotao.fb.Dog">
<property name="age">
<bean class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
<property name="targetObject">
<ref local="randomAge"/>
</property>
<property name="targetMethod">
<value>getAge</value>
</property>
</bean>
</property>
</bean>
<bean id="randomAge" class="com.baobaotao.fd.RandomAge" />
<bean id="bdog" class="com.baobaotao.fb.Dog">
<property name="age">
<bean class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
<property name="targetObject">
<ref local="randomAge"/>
</property>
<property name="targetMethod">
<value>getAge</value>
</property>
</bean>
</property>
</bean>
<bean id="randomAge" class="com.baobaotao.fd.RandomAge" />
對(duì)于靜態(tài)方法：
view plaincopy to clipboardprint?<bean id="bdog" class="com.baobaotao.fb.Dog">
<property name="age">
<bean class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
<property name="targetClass">
<value>com.baobaotao.fb.RandomAge</value>
</property>
<property name="targetMethod">
<!-- getAge必須是靜態(tài)方法 -->
<value>getAges</value>
</property>
</bean>
</property>
</bean>