• 《精通Spring4.X企业应用开发实战》读后感第四章(BeanFactory生命周期)


     

    package com.smart;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.*;
    
    public class Car implements BeanFactoryAware, BeanNameAware, InitializingBean, DisposableBean{
        private String brand;
        private String color;
        private int maxSpeed;
    
        private BeanFactory beanFactory;
        private String beanName;
    
        //默认构造函数
        public Car(){System.out.println("调用Car()构造函数");}
    
        //带参构造函数
        public Car(String brand, String color, int maxSpeed) {
            this.brand = brand;
            this.color = color;
            this.maxSpeed = maxSpeed;
        }
    
        //未带参方法
        public void introduce() {
            System.out.println("brand:" + brand + ";color:" + color + ";maxSpeed:" + maxSpeed);
        }
    
        public String getBrand() {
            return brand;
        }
    
        public void setBrand(String brand) {
            System.out.println("调用setBrand()设置属性");
            this.brand = brand;
        }
    
        public String getColor() {
            return color;
        }
    
        public void setColor(String color) {
            this.color = color;
        }
    
        public int getMaxSpeed() {
            return maxSpeed;
        }
    
        public void setMaxSpeed(int maxSpeed) {
            this.maxSpeed = maxSpeed;
        }
    
        // BeanFactoryAware接口方法
        public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
            System.out.println("调用BeanFactoryAware.setBeanFactory().");
            this.beanFactory = beanFactory;
        }
    
        // BeanNameAware接口方法
        public void setBeanName(String s) {
            System.out.println("调用BeanNameAware.setBeanName().");
            this.beanName = s;
        }
    
        // DisposableBean接口方法
        public void destroy() throws Exception {
            System.out.println("调用DisposableBean.destroy().");
        }
    
        // InitializingBean接口方法
        public void afterPropertiesSet() throws Exception {
            System.out.println("调用InitialingBean.afterPropertiesSet().");
        }
    
        // 通过<bean>的init-method属性指定的初始方法
        public void myInit() {
            System.out.println("调用init-method属性指定的myInit(), 将maxSpeed设置为240");
            this.maxSpeed = 240;
        }
    
        //同过<bean>的destroy-method属性指定的销毁方法
        public void myDestroy() {
            System.out.println("调用destroy-method属性指定的myDestroy().");
        }
    
    }

    package com.smart.beanfactory;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.PropertyValues;
    import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
    
    import java.beans.PropertyDescriptor;
    
    public class MyInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter {
    
        @Override
        // 1.接口方法,在实例化Bean前调用
        public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
            // 1-1. 仅对容器中的car Bean进行处理
            if ("car".equals(beanName)) {
                System.out.println("调用InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation().");
            }
            return null;
        }
    
        @Override
        // 2.接口方法,在实例化Bean后调用
        public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
            if ("car".equals(beanName)) {
                System.out.println("调用InstantiationAwarePostProcessor.postProcessorAfterInstantiation().");
            }
            return true;
        }
    
        @Override
        // 3.接口方法,在设置某个属性时调用
        public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {
            // 3-1. 仅对容器中的car Bean进行处理, 还可以同过pds入参进行过滤
            if ("car".equals(beanName)) {
                System.out.println("调用InstantiationAwarePostProcessor.postProcessPropertyValues().");
            }
            return pvs;
        }
    }

    package com.smart.beanfactory;
    
    import com.smart.Car;
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.config.BeanPostProcessor;
    
    public class MyBeanPostProcessor implements BeanPostProcessor {
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            if ("car".equals(beanName)) {
                Car car = (Car) bean;
                if (car.getColor() == null) {
                    System.out.println("调用BeanPostProcessor.postProcessBeforeInitialization()," +
                            "若color为空,设置为默认黑色");
                    car.setColor("黑色");
                }
            }
            return bean;
        }
    
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            if ("car".equals(beanName)) {
                Car car = (Car) bean;
                if (car.getMaxSpeed() >= 200) {
                    System.out.println("调用BeanPostProcessor.postProcessAfterInitialization()," +
                            "将maxSpeed设置为200");
                    car.setMaxSpeed(200);
                }
            }
            return bean;
        }
    }

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    
        <bean id="car" class="com.smart.Car"
              init-method="myInit"
              destroy-method="myDestroy"
              p:brand="红旗CA72"
              p:maxSpeed="200"/>
    
    </beans>

    package com.smart.beanfactory;
    
    import com.smart.Car;
    import org.springframework.beans.factory.BeanFactory;
    import org.springframework.beans.factory.config.ConfigurableBeanFactory;
    import org.springframework.beans.factory.support.DefaultListableBeanFactory;
    import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.core.io.ClassPathResource;
    import org.springframework.core.io.Resource;
    
    public class BeanLifeCycle {
        public static void lifeCycleInBeanFactory() {
            // 1. 装载配置文件并启动容器
            Resource res = new ClassPathResource("beans.xml");
            BeanFactory bf = new DefaultListableBeanFactory();
            XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader((DefaultListableBeanFactory) bf);
            reader.loadBeanDefinitions(res);
    
            //后处理器的实际调用顺序与注册顺序无关,在具有多个后处理器的情况下,必须通过实现
            //org.springframework.core.Ordered接口来确定调用顺序
            // 2. 向容器中注册MyBeanPostProcessor后处理器
            ((ConfigurableBeanFactory) bf).addBeanPostProcessor(new MyBeanPostProcessor());
            // 3. 向容器中注册MyInstantiationAwareBeanPostProcessor后处理器
            ((ConfigurableBeanFactory) bf).addBeanPostProcessor(new MyInstantiationAwareBeanPostProcessor());
    
            // 4. 第一次从容器中获得car, 将触发容器实例化该Bean,这将引发Bean生命周期方法的调用
            Car car1 = (Car) bf.getBean("car");
            car1.introduce();
            car1.setColor("红色");
    
            // 5. 第二次从容器中获取car, 直接从缓存池中获取
            Car car2 = (Car) bf.getBean("car");
    
            // 6. 查看car1和car2是否指向同一引用
            System.out.println("car1==car2: " + (car1 == car2));
    
            // 7. 关闭容器
            ((DefaultListableBeanFactory) bf).destroySingleton("car");
    
        }
    
        public static void main(String[] args) {
            lifeCycleInBeanFactory();
        }
    }

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  • 原文地址:https://www.cnblogs.com/Michael2397/p/7933195.html
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