《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();
    }
}