10.Bean对象的作用域和生命周期

bean scope属性

　bean scope属性用于决定对象何时被创建与作用范围，bean scope配置将影响容器内对象的数量，默认情况下bean会在IoC容器创建后自动实例化，全局唯一。

 

bean scope用法

<bean id="bookDao" class="com.spring.ioc.bookshop.dao.BookDaoOracleImpl" scrope="prototype"/>

bean scope属性清单

 singleton与prototype对比

　 singleton单例模式在Ioc容器初始化过程中创建bean对象，prototype多例模式在Ioc容器获取bean的时候创建bean对象，某一个属性在运行过程中如果恒定不变，则设置成单例，如果属性在运行过程中不断变化，则设置成多例。

 

bean生命周期

 

package com.spring.ioc.entity;

import com.sun.org.apache.xpath.internal.operations.Or;

public class Order {
    private Float price;
    private Integer quantity;
    private Float total;

    public Order(){
        System.out.println("构造方法 创建Order对象:"+this);
    }

    public void init(){
        System.out.println("执行init()方法");
        total = price * quantity;
    }

    public void destroy(){
        System.out.println("释放与订单对象相关的资源");
    }

    public void pay(){
        System.out.println("pay()方法 订单金额为:"+total);
    }

    public Float getPrice() {
        return price;
    }
    public void setPrice(Float price) {
        System.out.println("setPrice 设置price:"+price);
        this.price = price;
    }
    public Integer getQuantity() {
        return quantity;
    }
    public void setQuantity(Integer quantity) {
        System.out.println("setQuantity 设置quantity:"+quantity);
        this.quantity = quantity;
    }
    public Float getTotal() {
        return total;
    }
    public void setTotal(Float total) {
        this.total = total;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="order1" class="com.spring.ioc.entity.Order" init-method="init" destroy-method="destroy">
        <property name="price" value="19.8"/>
        <property name="quantity" value="1000"/>
    </bean>
</beans>

package com.spring.ioc;

import com.spring.ioc.entity.Order;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringApplication {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        System.out.println("=======Ioc容器初始化========");
        Order order1 = context.getBean("order1", Order.class);
        order1.pay();
        ((ClassPathXmlApplicationContext) context).registerShutdownHook();
    }
}