spring IOC构造器注入使用

运行主类

package com.beans;

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

public class Main {

  public static void main(String[] args) {
    
       //1.创建spring的IOC容器对象
    //ApplicationContext 代表IOC容器 是 BeanFactory 接口的子接口
    
    // ClassPathXmlApplicationContext: 是 ApplicationContext的实现类，从类路径下来加载配置文件
        ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        
        //2.从IOC容器中获取bean实例
        //利用id定位到IOC容器中的bean
      
        Car car=ctx.getBean(car);
        System.out.println(car);
  }

}      

Car类

package com.beans;

public class Car {
     private String brand;
     private String corp;
       private double price;
       private int maxSpeed;
       
       public Car(String brand, String corp, double price, int maxSpeed) {
      super();
      this.brand = brand;
      this.corp = corp;
      this.price = price;
      this.maxSpeed = maxSpeed;
    }
       @Override
    public String toString() {
      return "Car [brand=" + brand + ", corp=" + corp + ", price=" + price + ", maxSpeed=" + maxSpeed + "]";
    }

}      

<constructor-arg value="Audi" index="0"></constructor-arg>      

<?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">

    <!-- 配置bean 
    class :bean 的全类名，通过反射的方式在IOC容器中创建bean，所以要求必须要有无参的构造器
    id： 表示容器中唯一的id
    -->
    

    <!--通过构造方法配置bean的属性 -->
    <bean id="car" class="com.beans.Car">
    <constructor-arg value="Audi" index="0"></constructor-arg>
    <constructor-arg value="ShangHai" index="1"></constructor-arg>
    <constructor-arg value="30000" index="2"></constructor-arg>
    <constructor-arg value="200" index="3"></constructor-arg>
    </bean>
    
    
</beans>