initMethod和destroyMethod
Bean定义
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public class Car {
public Car() {
System.out.println( "car constructor" );
}
public void init(){
System.out.println( "car init" );
}
public void destroy(){
System.out.println( "car destroy" );
}
}
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配置类
- bean创建--初始化--销毁
- 可以自定义初始化和销毁方法
- 初始化:对象创建完成,并赋值完成,调用初始化方法
- 销毁: 容器关闭进行销毁(单实例)
多实例容器不会管理这个bean
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@Configuration
public class MyCOnfigOfLifeCycle {
@Bean (initMethod = "init" ,destroyMethod = "destroy" )
public Car car(){
return new Car();
}
}
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获取容器
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@Test
public void test01(){
printBeans(applicationContext);
// 关闭容器
applicationContext.close();
}
private void printBeans(AnnotationConfigApplicationContext applicationContext){
String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();
for (String beanDefinitionName : beanDefinitionNames) {
System.out.println(beanDefinitionName);
}
}
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InitializingBean和DisposableBean
Bean定义
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public class Cat implements InitializingBean, DisposableBean {
@Override
public void destroy() throws Exception {
System.out.println( "cat destroy" );
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println( "cat initialize" );
}
}
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实现了InitializingBean和Disposable后,也可以实现初始化和销毁的方法
PostConstruct和PreDestroy
Bean定义
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public class Dog {
public Dog(){
System.out.println( "dog constructor" );
}
@PostConstruct
public void init(){
System.out.println( "dog init" );
}
@PreDestroy
public void destroy(){
System.out.println( "dog destroy" );
}
}
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BeanPostProcessor
bean
定义
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public class MyBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
System.out.println( "before init" + beanName);
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
System.out.println( "after init" + beanName);
return bean;
}
}
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加入到bean中,可以发现每个bean初始化前后都会执行功能
- postProcessBeforeInitialization将在一个bean被完全初始化前进行回调,此时对应的bean已经实例化了,但是对应的属性注入等还没有进行,即在调用InitializingBean的afterPropertiesSet()方法或bean对应的init-method之前
- postProcessAfterInitialization将在bean被完全初始化后进行回调,此时对应的依赖注入已经完成,即在调用InitializingBean的afterPropertiesSet()方法或对应init-method方法之后。
postProcessBeforeInitialization方法的返回值会被Spring容器作为处理后的Bean注册到容器中。如果你在postProcessBeforeInitialization方法中重新构造了一个Bean进行返回,而不是返回参数中的bean;那么你返回的Bean将会被注册到Spring容器中。而原来在Spring中配置的Bean(被Spring实例化的Bean)将会被覆盖。
一旦这两个方法返回null,就不会执行后面的postProcessBefore/AfterInitialization,(在applyBeanPostProcessorsBeforeInitialization中)
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for (Iterator var4 = this .getBeanPostProcessors().iterator(); var4.hasNext(); result = current) {
BeanPostProcessor processor = (BeanPostProcessor)var4.next();
current = processor.postProcessBeforeInitialization(result, beanName);
if (current == null ) {
return result;
}
}
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步骤:
populateBean给Bean赋值
initializeBean{ applyBeanPostProcessorsBeforeInitialization,
invokeInitMethods, // 自定义初始化
applyBeanPostProcessorsAfterInitialization}
底层使用
bean赋值,bean注入,@autowire,生命周期注解功能,@Async
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://www.cnblogs.com/jimmyhe/p/13661809.html