spring的钩子_Spring 中的几个常用的钩子接口

1.Aware接口

Awear 这个单词的意思是知道的，所以可以猜想以Awear 结尾的接口意思可以把他知道的东西告诉我们。常用的Awear接口有 ApplicationContextAware和 BeanFactoryAware，另外还有BeanNameAware 和EnvironmentAware

(1)ApplicationContextAware 接口 可以返回  ApplicationContext，也就是容器本身，我们可以通过ApplicationContext 这个容器对象做很多事，最常见的是获取Bean，和判断当前容器是否包含某个组件。下面的示例是通过ApplicationContext 获取Bean的示例(工程基于SpringBoot2.2.1.RELEASE)

packagecom.spring.hook.compent;importorg.springframework.beans.BeansException;importorg.springframework.context.ApplicationContext;importorg.springframework.context.ApplicationContextAware;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 13:51

* @desc*/@Componentpublic class SpringContextAware implementsApplicationContextAware {private staticApplicationContext app;

@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throwsBeansException {

app=applicationContext;

}public static T getBeanByClass(Classclazz){returnapp.getBean(clazz);

}public static Class>getBeanByType(String type){returnapp.getType(type);

}

@SuppressWarnings(“unchecked”)public static T getBeanByName(String name){return(T) app.getBean(name);

}

}

(2)BeanFactoryAware 。通过实现 BeanFactoryAware 可以获取BeanFactory。Beanfactory 作用和ApplicationContext 类似，BeanFactory 比ApplicationContext更底层一些， 当然功能更加单一一些，ApplicationContext 在此基础做了一些加强，比如多了国际化等一些信息。

packagecom.spring.hook.compent;importorg.springframework.beans.BeansException;importorg.springframework.beans.factory.BeanFactory;importorg.springframework.beans.factory.BeanFactoryAware;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 16:48

* @desc*/@Componentpublic class BeanFactoryContext implementsBeanFactoryAware{private staticBeanFactory beanFactory;

@Overridepublic void setBeanFactory(BeanFactory beanFactory) throwsBeansException {

BeanFactoryContext.beanFactory=beanFactory;

}public static T getBeanByClass(Classclazz){returnbeanFactory.getBean(clazz);

}

}

(3)BeanNameAware。这个接口个人感觉作用不明显，通过实现这个接口可以获取当前Bean的名称。

packagecom.spring.hook.compent;importorg.springframework.beans.factory.BeanNameAware;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 14:19

* @desc*/@Componentpublic class Car implementsBeanNameAware{

@Overridepublic voidsetBeanName(String s) {

System.out.println(“BeanName:”+s);

}privateString brand;privateString color;publicString getCarAttr(){return “品牌：”+brand+” 颜色：”+color;

}public voidsetBrand(String brand) {this.brand =brand;

}public voidsetColor(String color) {this.color =color;

}

}

(4)EnvironmentAware 通过实现这个接口可以获取当前运行环境的一些信息。

packagecom.spring.hook.compent;importorg.springframework.context.EnvironmentAware;importorg.springframework.core.env.Environment;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 17:25

* @desc*/@Componentpublic class EnvironmentContext implementsEnvironmentAware {

@Overridepublic voidsetEnvironment(Environment environment) {

String[] activeProfile=environment.getActiveProfiles();

String[] defaultProfile=environment.getDefaultProfiles();

String port= environment.getProperty(“dog.type”);

}

}

2.InitializingBean,DisposableBean 通过实现这两个接口可以在Bean初始化后和摧毁钱做一些事。InitializingBean 接口的afterPropertiesSet() 方法在set属性完成后执行，DisposableBean 的 destroy() 方法在bean摧毁前BeanFactory执行

packagecom.spring.hook.compent;importorg.springframework.beans.factory.DisposableBean;importorg.springframework.beans.factory.InitializingBean;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 17:45

* @desc*/@Componentpublic class Fruit implementsInitializingBean,DisposableBean{

@Overridepublic void destroy() throwsException {

System.out.println(“我要被销毁了”);

}

@Overridepublic void afterPropertiesSet() throwsException {

System.out.println(“我原来的名字叫：”+name);

name= “苹果”;

}privateString name;publicString getName() {returnname;

}public voidsetName(String name) {this.name =name;

}

}

3.PostProcessor 这个接口被称为后置处理器，常见的有：BeanPostProcessor，BeanFactoryPostProcessor ，分别为Bean的后置处理器和BeanFactory的后置处理器。

(1)BeanPostProcessor 能再Bean的初始化前后做一些事，但是个人感觉很功能很单一，无法返回具体的Bean

packagecom.spring.hook.compent;importorg.springframework.beans.BeansException;importorg.springframework.beans.factory.config.BeanPostProcessor;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 18:19

* @desc*/@Componentpublic class BeanPostProcessorImpl implementsBeanPostProcessor{

@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throwsBeansException {

System.out.println(“初始化前BeanName:”+beanName);returnbean;

}

@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throwsBeansException {

System.out.println(“初始化后BeanName:”+beanName);returnbean;

}

}

(2)BeanFactoryPostProcessor

packagecom.spring.hook.compent;importorg.springframework.beans.BeansException;importorg.springframework.beans.MutablePropertyValues;importorg.springframework.beans.factory.config.BeanDefinition;importorg.springframework.beans.factory.config.BeanFactoryPostProcessor;importorg.springframework.beans.factory.config.ConfigurableListableBeanFactory;importorg.springframework.stereotype.Component;/* @Author lizhilong

* @create 2019/11/28 18:29

* @desc*/@Componentpublic class BeanPostFactoryContextImpl implementsBeanFactoryPostProcessor {private staticConfigurableListableBeanFactory beanFactory;

@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throwsBeansException {

beanFactory=configurableListableBeanFactory;if(beanFactory.containsBean(“fruit”)){

BeanDefinition fruit= beanFactory.getBeanDefinition(“fruit”);

MutablePropertyValues propertyValues=fruit.getPropertyValues();

propertyValues.add(“name”,”香蕉”);

}

Fruit fruit= (Fruit)beanFactory.getBean(“fruit”);

System.out.println(“我现在的名字叫：”+fruit.getName());

}

}

示例中我们在不同的时刻为 Fruit 的name属性赋值，运行结果：

我原来的名字叫：香蕉

我现在的名字叫：苹果