spring IOC用ref属性实现bean之间的引用

谁借莪１个温暖的怀抱￠ 2022-04-02 04:26 232阅读 0赞

如下图所示，用ref属性建立bean之间的引用

下面是car2的bean

下面贴出整个项目的完整代码，可以自己新建一个项目贴上去试下。  
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);
            
            Person person=(Person)ctx.getBean("person");
            System.out.println(person);
    	}
    
    }

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) {
       		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 + "]";
       	}
    
          
    }

Person类

package com.beans;
    
    public class Person {
       
    	private String name;
    	private int age;
        private Car car;
        @Override
       	public String toString() {
       		return "Person [name=" + name + ", age=" + age + ", car=" + car + "]";
       	}
        public String getName() {
     		return name;
     	}
     	public void setName(String name) {
     		this.name = name;
     	}
     	public int getAge() {
     		return age;
     	}
     	public void setAge(int age) {
     		this.age = age;
     	}
     	public Car getCar() {
     		return car;
     	}
     	public void setCar(Car car) {
     		this.car = car;
     	}
    }

applicationContext. xml 配置文件

<?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="car" class="com.beans.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg  index="1">
        <value><![CDATA[<ShangHai>]]></value>
        </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" type="int"></constructor-arg>
        </bean>
        
        <bean id="person" class="com.beans.Person">
        <property name="name" value="tom"></property>
        <property name="age" value="20"></property>
        
        <property name="car" ref="car2"></property>
        </bean>
        
        
    </beans>

运行结果如下  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3Nzc0MTcx_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3Nzc0MTcx_size_16_color_FFFFFF_t_70]: /images/20220402/8bfeac99e1a3467f8a7a522c5c70b9ac.png