Spring配置使用之Bean生命周期详解

public class Animals {
   public Animals(){
     System.out.println("creating...");
   }
}

<!-- 表示启用了延迟加载 -->
<bean id="animals" class="com.demo.Animals" lazy-init="true"/>

<!-- 不启用延迟加载 -->
<bean id="animals" class="com.demo.Animals" lazy-init="default"/>
<bean id="animals" class="com.demo.Animals" />

// 创建容器
String location = ...
ApplicationContext factory = new FileSystemXmlApplicationContext(location);

// 输出结果：
// 若启用了 lazy-init 则输出 creating...，否则无打印信息。

public class BeanOne{
   public BeanOne(){
     System.out.println("BeanOne...");
   }
}
public class BeanTwo{
   public BeanTwon(){
     System.out.println("BeanTwo...");
   }
}

<bean id="beanOne" class="com.demo.BeanOne" lazy-init="true" depends-on="beanTwo" /> 
<bean id="beanTwo" class="com.demo.BeanTwo" lazy-init="true" /> 

String location = ...
ApplicationContext factory = new FileSystemXmlApplicationContext(location);
BeanOne beanOne= (BeanOne)factory.getBean("beanOne");
// 输出结果：
// BeanTwo...
// BeanOne...

// 进入房间后要开灯，离开房间后要关灯
public class Room {
  public Room(){
    System.out.println("enter room...");
  }
  public void turnOnLights(){
    System.out.println("turn on...");
  }
  public void turnOffLights(){
    System.out.println("turn off...");
  }
}

<bean class="com.demo.Room" init-method="turnOnLights" destroy-method="turnOffLights"/>

// 实例化 Bean
FileSystemXmlApplicationContext context = ...
// 销毁 Bean
context.registerShutdownHook(); 
// 输出内容：
// enter room...
// turn on...
// turn off...