spring IOC一个类有多个构造器,用构造器注入怎么解决匹配问题

Car 类写入两个构造器(参数不同)

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) {
   		super();
   		this.brand = brand;
   		this.corp = corp;
   		this.price = price;
   	}
       
       public Car(String brand, String corp, int maxSpeed) {
   		super();
   		this.brand = brand;
   		this.corp = corp;
   		this.maxSpeed = maxSpeed;
   	}

       @Override
   	public String toString() {
   		return "Car [brand=" + brand + ", corp=" + corp + ", price=" + price + ", maxSpeed=" + maxSpeed + "]";
   	}
}

配置文件如下

<?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>
    
    </bean>
    
    <bean id="car2" class="com.beans.Car">
    <constructor-arg value="Boma"></constructor-arg>
    <constructor-arg value="ChangSha"></constructor-arg>
    <constructor-arg value="240"></constructor-arg>
    </bean>
    
    
</beans>

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=(Car)ctx.getBean("car");
        System.out.println(car);
        
        Car car2=(Car)ctx.getBean("car2");
        System.out.println(car2);
	}

}
运行结果如图所示,都匹配到了第一个构造器。

在这里插入图片描述

那么怎么让第二个bean匹配到第二个构造器呢?
加一下属性类型就可以了,如下图

 <bean id="car2" class="com.beans.Car">
    <constructor-arg value="Boma"></constructor-arg>
    <constructor-arg value="ChangSha"></constructor-arg>
    <constructor-arg value="240" type="int"></constructor-arg>
    </bean>

再次运行。it is ok.
在这里插入图片描述

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转载自blog.csdn.net/qq_37774171/article/details/85231911