Spring 管理bean的生命周期

两个生命周期时间与bean关系尤为重要： 
postinitialization（初始化后）和predestruction（销毁前）。 

（Spring并不管理那些被配置成非单例bean的生命周期） 



指定初始化方法： 
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1. package cn.partner4java.init;  
2.   
3. /** 
4. * 指定初始化方法 
5. * @author partner4java 
6. * 
7. */  
8. public class SimpleBean {  
9.     private String name;  
10.     private int age = 0;  
11.       
12.     public void init(){  
13.         if(name == null){  
14.             System.out.println("name为空");  
15.         }  
16.         if(age == 0){  
17.             System.out.println("age为0");  
18.         }  
19.     }  
20.       
21.     public String getName() {  
22.         return name;  
23.     }  
24.     public void setName(String name) {  
25.         this.name = name;  
26.     }  
27.     public int getAge() {  
28.         return age;  
29.     }  
30.     public void setAge(int age) {  
31.         this.age = age;  
32.     }  
33.       
34. }  

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.        xsi:schemaLocation="  
5.                 http://www.springframework.org/schema/beans  
6.                 http://www.springframework.org/schema/beans/spring-beans.xsd">  
7.                   
8.     <bean id="simple1" class="cn.partner4java.init.SimpleBean"  
9.             init-method="init">  
10.         <property name="age" value="29"/>  
11.         <property name="name" value="Dr. Jekyll"/>  
12.     </bean>  
13.     <bean id="simple2" class="cn.partner4java.init.SimpleBean"  
14.             init-method="init">  
15.         <property name="age" value="29"/>  
16.     </bean>  
17.     <bean id="simple3" class="cn.partner4java.init.SimpleBean"  
18.             init-method="init">  
19.         <property name="name" value="Mr. Hyde"/>  
20.     </bean>  
21.   
22. </beans>  

调用：view plaincopy to clipboardprint?

1.         //在调用获取的时候就会调用init，在调用init之前，已经使用控制反转设置方法依赖注入设置进数据  
2.         BeanFactory beanFactory = getBeanFactory();  
3.         System.out.println("simple1");  
4.         beanFactory.getBean("simple1");  
5.         System.out.println("simple2");  
6.         beanFactory.getBean("simple2");  
7.         System.out.println("simple3");  
8.         beanFactory.getBean("simple3");  
9.           
10. //      后台打印：  
11. //      simple1  
12. //      simple2  
13. //      name为空  
14. //      simple3  
15. //      age为0  

实现InitializingBean接口： 
Spring中InitializingBean接口允许你在bean的代码中这样定义：你希望bean能接收到Spring已经完成对其配置的通知。就像使用初始化方法时一样，你可以借机检查bean的配置以确保其有效，若要必要，还可以给出默认值。view plaincopy to clipboardprint?

1. public class SimpleBeanIB implements InitializingBean {  
2.     private static final String DEFAULT_NAME = "Jan Machacek";  
3.     private String name;  
4.     private int age = 0;  
5.   
6.     public String getName() {  
7.         return name;  
8.     }  
9.   
10.     public void setName(String name) {  
11.         this.name = name;  
12.     }  
13.   
14.     public int getAge() {  
15.         return age;  
16.     }  
17.   
18.     public void setAge(int age) {  
19.         this.age = age;  
20.     }  
21.   
22.     @Override  
23.     public String toString() {  
24.         final StringBuilder sb = new StringBuilder();  
25.         sb.append("SimpleBean");  
26.         sb.append("{name='").append(name).append('\'');  
27.         sb.append(", age=").append(age);  
28.         sb.append('}');  
29.         return sb.toString();  
30.     }  
31.   
32.     public void afterPropertiesSet() throws Exception {  
33.         System.out.println("initializing bean");  
34.         if (this.name == null) {  
35.             System.out.println("No name specified, using default.");  
36.             this.name = DEFAULT_NAME;  
37.         }  
38.         if (this.age == 0) {  
39.             throw new IllegalArgumentException("You must set the [age] property bean of type [" + getClass().getName() + "]");  
40.         }  
41.     }  
42. }  

决议顺序： 
Spring首先调用InitializingBean.afterPropertiesSet()方法，然后再调用初始化方法。（建议如果存在顺序，都写入到afterPropertiesSet中调用。） 


afterPropertiesSet方法和类的继承： 
例子抽象父类实现了接口，但是把afterPropertiesSet定义成了final，不可被子类覆盖，也就是去实现一些通用的初始化，然后再调用了自己定义的initSimple()初始化方法。 
父类：view plaincopy to clipboardprint?

1. public abstract class SimpleBeanSupport implements InitializingBean {  
2.     private String value;  
3.   
4.     /** 
5.      * Subclasses may override this method to perform additional initialization. 
6.      * This method gets invoked after the initialization of the {@link SimpleBeanSupport} 
7.      * completes. 
8.      * @throws Exception If the subclass initialization fails. 
9.      */  
10.     protected void initSimple() throws Exception {  
11.         // do nothing  
12.     }  
13.   
14.     public final void afterPropertiesSet() throws Exception {  
15.         Assert.notNull(this.value, "The [value] property of [" + getClass().getName() + "] must be set.");  
16.         initSimple();  
17.     }  
18.   
19.     public final void setValue(String value) {  
20.         this.value = value;  
21.     }  
22.   
23.     protected final String getValue() {  
24.         return this.value;  
25.     }  
26. }  

继承：view plaincopy to clipboardprint?

1. public class SoutSimpleBean extends SimpleBeanSupport {  
2.     private String person;  
3.   
4.     protected void initSimple() throws Exception {  
5.         Assert.notNull(this.person, "The [person] property of [" + getClass().getName() + "] must be set.");  
6.     }  
7.   
8.     public void setPerson(String person) {  
9.         this.person = person;  
10.     }  
11.   
12.     @Override  
13.     public String toString() {  
14.         return String.format("%s says \"%s\"", this.person, getValue());  
15.     }  
16. }  

配置文件：view plaincopy to clipboardprint?

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.        xsi:schemaLocation="  
5.                 http://www.springframework.org/schema/beans  
6.                 http://www.springframework.org/schema/beans/spring-beans.xsd">  
7.   
8.     <bean id="simple1" class="com.apress.prospring2.ch04.lifecycle.SoutSimpleBean">  
9.         <property name="person" value="Winston Churchill"/>  
10.         <property name="value" value="This report, by its very length, defends itself against the risk of being read."/>  
11.     </bean>  
12.   
13. </beans>  

嵌入bean的销毁： 
1、bean销毁时执行某一方法view plaincopy to clipboardprint?

1. public class DestructiveBean implements InitializingBean {  
2.     private InputStream is = null;  
3.     private String filePath = null;  
4.   
5.     public void afterPropertiesSet() throws Exception {  
6.         System.out.println("Initializing Bean");  
7.   
8.         Assert.notNull(this.filePath, "The [filePath] property of [" + getClass().getName() + "] must be set.");  
9.   
10.         new File(this.filePath).createNewFile();  
11.         this.is = new FileInputStream(this.filePath);  
12.     }  
13.   
14.     public void destroy() {  
15.         System.out.println("Destroying Bean");  
16.   
17.         if (this.is != null) {  
18.             try {  
19.                 this.is.close();  
20.                 this.is = null;  
21.                 new File(this.filePath).delete();  
22.             } catch (IOException ex) {  
23.                 System.err.println("WARN: An IOException occured"  
24.                         + " while trying to close the InputStream");  
25.             }  
26.         }  
27.     }  
28.   
29.     public void setFilePath(String filePath) {  
30.         this.filePath = filePath;  
31.     }  
32.   
33.     @Override  
34.     public String toString() {  
35.         final StringBuilder sb = new StringBuilder();  
36.         sb.append("DestructiveBean");  
37.         sb.append("{is=").append(is);  
38.         sb.append(", filePath='").append(filePath).append('\'');  
39.         sb.append('}');  
40.         return sb.toString();  
41.     }  
42. }  

配置文件：view plaincopy to clipboardprint?

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.        xsi:schemaLocation="  
5.                 http://www.springframework.org/schema/beans  
6.                 http://www.springframework.org/schema/beans/spring-beans.xsd">  
7.   
8.     <bean id="destructive" class="com.apress.prospring2.ch04.lifecycle.DestructiveBean"  
9.             destroy-method="destroy">  
10.         <property name="filePath" value="/tmp/prospring25"/>  
11.     </bean>  
12.   
13. </beans>  

2、实现DisposableBean接口 
DisposableBean接口提供了destory方法。view plaincopy to clipboardprint?

1. public class DestructiveBeanI implements InitializingBean, DisposableBean {  
2.     private InputStream is = null;  
3.     private String filePath = null;  
4.   
5.     public void afterPropertiesSet() throws Exception {  
6.         System.out.println("Initializing Bean");  
7.   
8.         Assert.notNull(this.filePath, "The [filePath] property of [" + getClass().getName() + "] must be set.");  
9.   
10.         new File(this.filePath).createNewFile();  
11.         this.is = new FileInputStream(this.filePath);  
12.     }  
13.   
14.     public void destroy() {  
15.         System.out.println("Destroying Bean");  
16.   
17.         if (this.is != null) {  
18.             try {  
19.                 this.is.close();  
20.                 this.is = null;  
21.                 new File(this.filePath).delete();  
22.             } catch (IOException ex) {  
23.                 System.err.println("WARN: An IOException occured"  
24.                         + " while trying to close the InputStream");  
25.             }  
26.         }  
27.     }  
28.   
29.     public void setFilePath(String filePath) {  
30.         this.filePath = filePath;  
31.     }  
32.   
33.     @Override  
34.     public String toString() {  
35.         final StringBuilder sb = new StringBuilder();  
36.         sb.append("DestructiveBean");  
37.         sb.append("{is=").append(is);  
38.         sb.append(", filePath='").append(filePath).append('\'');  
39.         sb.append('}');  
40.         return sb.toString();  
41.     }  
42. }  

配置文件：view plaincopy to clipboardprint?

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.        xsi:schemaLocation="  
5.                 http://www.springframework.org/schema/beans  
6.                 http://www.springframework.org/schema/beans/spring-beans.xsd">  
7.   
8.     <bean id="destructive" class="com.apress.prospring2.ch04.lifecycle.DestructiveBeanI">  
9.         <property name="filePath" value="/tmp/prospring25"/>  
10.     </bean>  
11.   
12. </beans>  

3、使用关闭钩子 
注入关闭代码：view plaincopy to clipboardprint?

1. public class ShutdownHook implements Runnable {  
2.     private ConfigurableListableBeanFactory beanFactory;  
3.   
4.     public ShutdownHook(ConfigurableListableBeanFactory beanFactory) {  
5.         Assert.notNull(beanFactory, "The 'beanFactory' argument must not be null.");  
6.         this.beanFactory = beanFactory;  
7.     }  
8.   
9.     public void run() {  
10.         this.beanFactory.destroySingletons();  
11.     }  
12. }  

调用代码：view plaincopy to clipboardprint?

1. public class ShutdownHookDemo {  
2.   
3.     public static void main(String[] args) throws IOException {  
4.         XmlBeanFactory factory = new XmlBeanFactory(new ClassPathResource("/META-INF/spring/lifecycledemo5-context.xml"));  
5.         Runtime.getRuntime().addShutdownHook(new Thread(new ShutdownHook(factory)));  
6.         new BufferedInputStream(System.in).read();  
7.     }  
8.   
9. }