Spring 学习笔记 - IOC/依赖注入

简述：

Spring 学习 - IOC/依赖注入

1. Bean 的实例化

1) 直接使用原始类创建bean

<bean id="exampleBean" class="com.anialy.test.ExampleBean" />

2) 使用工厂方法创建bean

</pre><pre name="code" class="html"><bean id="exampleBean" class="com.anialy.test.ExampleBean" factory-method="createInstance" />

3) 使用工厂类创建bean

<bean id="baseBean" class="com.anialy.test.BaseBean" />
<bean id="exampleBean" factory-bean="baseBean" factory-method="createInstance" />

2.Bean 注入方式

1）Setter Injection

<bean id="exampleBean" class="com.anialy.test.ExampleBean">
    <property name="beanOne">
        <ref bean="anotherExampleBean" />
    </property>
    <property name="beanTwo" ref="yetAnotherBean" />
    <property name="integerProperty" value="10" />
</bean>

2) Constructor Injection(构造函数注入)

<bean id="exampleBean" class="com.anialy.test.ExampleBean>
    <constructor-arg type="int" value="100" />
    <constructor-arg type="java.lang.String" value="stringVal" />
</bean>

3. 几种特殊对象的注入

1）Inner Beans

<bean id="outter" class="com.anialy.test.Outter">
    <property name="inner">
        <bean class="com.anialy.test.Inner" />
    </property>
</bean>

2) Collections - Map

<bean id="exampleBean" class="com.anialy.test.ExampleBean">
    <property name="map" >
        <map>
            <entry key="one" value="1.11" />
        </map>
    </property>
</bean>

3) NULLS

<bean class="com.anialy.test.ExampleBean">
    <property name="name"><null /></property>
</bean>

4. Bean的scope

1. prototype, 每次getBean时都会创建一个新的实例

<bean id="exampleBean" class="com.anialy.test.ExampleBean" scope="prototype" />

2. singleton, 每次getBean时都获取同一个实例

<bean id="exampleBean" class="com.anialy.test.ExampleBean" scope="singleton" />

5. 自定义初始化

1) 自定义

public class ExampleBean {
    public void init() {
        // do initialization work
    }
}

<bean id="exampleBean" class="com.anialy.test.ExampleBean" init-method="init" />

2) 实现Spring约定的接口

public class ExampleBean implements InitializingBean {

	@Override
	public void afterPropertiesSet() throws Exception {
		// TODO initialization work
		
	}

}

6. 自定义销毁

1）自定义

public class ExampleBean {
    public void destroy() {
    }
}

<bean id="exampleBean" class="com.anialy.test.ExampleBean" destroy-method="destroy" />

2）实现Spring提供的接口

public class ExampleBean implements DisposableBean {

	@Override
	public void destroy() throws Exception {
		// do some destroy work
	}

}

7. Bean的依赖

一个Bean必须等到其他bean被成功加载后才能加载

<bean id="bean2" class="com.anialy.test.Bean2" depends-on="bean1" />
	<bean id="bean1" class="com.anialy.test.Bean1" />

8. Bean的延迟初始化

一个Bean只有当被其他Bean引用到，才真正创建实例

1） 单个Bean配置

<bean id="exampleBean" class="com.anialy.test.ExampleBean" lazy-init="true" />

2) 所有的Bean默认的延迟初始化配置

<beans default-lazy-init="true"></beans>

9. Bean的继承

	<bean id="parentBean" abstract="true" >
	    <property name="name">
	        <value>anialy</value>
	    </property>
	    <property name="age">
	        <value>11</value>
	    </property>
	</bean>
	
	<bean id="childBean"  class="com.anialy.test.ChildBean"  parent="parentBean">
	    <property name="name">
	        <value>anialy-child</value>
	    </property>
	</bean>