006.初始化IoC容器（基于XML配置Bean 利用带参构造方法实例化对象）03

1.实例化bean的三种方式

 2.初始化Ioc容器

2.1   利用构造方法参数名实例化

 2.2 利用构造方法参数位置实例化

 2.3  实现步骤

2.3.1  src/main/java/com/imooc/spring/ioc/entity/Apple.java

package com.imooc.spring.ioc.entity;

public class Apple
{
    private String title;
    private String color;
    private String origin;

    public Apple()
    {
        //如果bean中不写属性，默认调用构造方法
        System.out.println("Apple对象已创建，" + this);
    }

    public Apple(String title, String color, String origin)
    {
        System.out.println("通过带参构造方法创建对象，" + this);
        this.title = title;
        this.color = color;
        this.origin = origin;
    }

    public String getTitle()
    {
        return title;
    }

    public void setTitle(String title)
    {
        this.title = title;
    }

    public String getColor()
    {
        return color;
    }

    public void setColor(String color)
    {
        this.color = color;
    }

    public String getOrigin()
    {
        return origin;
    }

    public void setOrigin(String origin)
    {
        this.origin = origin;
    }
}

2.3.3 src/main/resources/applicationContext.xml

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--bean标签默认通过构造方法构造对象-->
    <!--bean标签的作用是用于通知IOC容器实例化那个对象-->
    <!--class代表从那个类实例化-->
    <!--id代表标识-->
    <bean id="apple1" class="com.imooc.spring.ioc.entity.Apple">

    </bean>

    <bean id="apple2" class="com.imooc.spring.ioc.entity.Apple">
        <constructor-arg name="title" value="红富士"/>
        <constructor-arg name="color" value="红色"/>
        <constructor-arg name="origin" value="欧洲"/>
    </bean>

</beans>

2.3.4 src/main/java/com/imooc/spring/ioc/SpringApplication.java

package com.imooc.spring.ioc;


import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringApplication
{
    public static void main(String[] args)
    {

        //创建SpringIoc容器，并根据配置文件在容器中实例化
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");

    }
}

2.3.5 作为在构造方法中的参数并不强制要求为String类型，可以为数字类型

package com.imooc.spring.ioc.entity;

public class Apple
{
    private String title;
    private String color;
    private String origin;
    private Float price;

    public Apple()
    {
        //如果bean中不写属性，默认调用构造方法
        System.out.println("Apple对象已创建，" + this);
    }

    public Apple(String title, String color, String origin)
    {
        System.out.println("通过带参构造方法创建对象，" + this);
        this.title = title;
        this.color = color;
        this.origin = origin;
    }

    public Apple(String title, String color, String origin, Float price)
    {
        System.out.println("通过带参构造方法创建对象，" + this);
        this.title = title;
        this.color = color;
        this.origin = origin;
        this.price = price;
    }

    public String getTitle()
    {
        return title;
    }

    public void setTitle(String title)
    {
        this.title = title;
    }

    public String getColor()
    {
        return color;
    }

    public void setColor(String color)
    {
        this.color = color;
    }

    public String getOrigin()
    {
        return origin;
    }

    public void setOrigin(String origin)
    {
        this.origin = origin;
    }

    public Float getPrice()
    {
        return price;
    }

    public void setPrice(Float price)
    {
        this.price = price;
    }
}

2.3.6   src/main/resources/applicationContext.xml   利用构造方法参数位置实例化

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--bean标签默认通过构造方法构造对象-->
    <!--bean标签的作用是用于通知IOC容器实例化那个对象-->
    <!--class代表从那个类实例化-->
    <!--id代表标识-->
    <bean id="apple1" class="com.imooc.spring.ioc.entity.Apple">

    </bean>

    <bean id="apple2" class="com.imooc.spring.ioc.entity.Apple">
        <constructor-arg name="title" value="红富士"/>
        <constructor-arg name="color" value="红色"/>
        <constructor-arg name="origin" value="欧洲"/>
        <constructor-arg name="price" value="11.98"/>
    </bean>

    <bean id="apple3" class="com.imooc.spring.ioc.entity.Apple">
        <constructor-arg index="0" value="红富士"/>
        <constructor-arg index="1" value="红色"/>
        <constructor-arg index="2" value="欧洲"/>
        <constructor-arg index="3" value="11.98"/>
    </bean>

</beans>