spring中ref標簽的用法

1、作用

將對象值注入到對應的屬性，依賴於配置標簽實現

2、屬性

• bean：通過該屬性可以引用同一容器或父容器中的bean對象
• parent： 引用父容器中的bean

3、用法

bean屬性用法比較簡單，這里就不再介紹，主要講一下parent屬性的用法

前提

• 一個Boss類中有name，Car屬性，對應一個BossBean.xml配置文件
• 一個Car類中有brand、price、color屬性，對應一個CarBean.xml配置文件

需求

• 在BossBean.xml配置文件中引用CarBean.xml配置文件的bean

Boos類

package com.yl.bean;

public class Boss {
    private String name;
    private Car car;

    public Boss() {
    }

    public Boss(String name, Car car) {
        this.name = name;
        this.car = car;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Car getCar() {
        return car;
    }

    public void setCar(Car car) {
        this.car = car;
    }
}

Car類

package com.yl.bean;

public class Car {
    private String brand;
    private Integer price;
    private String color;

    public Car() {
    }

    public Car(String brand, Integer price, String color) {
        this.brand = brand;
        this.price = price;
        this.color = color;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public Integer getPrice() {
        return price;
    }

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

    public String getColor() {
        return color;
    }

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

BossBean.xml配置文件（父容器）

<?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">

    <!--Boss-->
    <bean id="boss" class="com.yl.bean.Boss">
        <property name="name" value="yl001"></property>
        
        <property name="car">
            <!--引用父容器中的car-->
            <ref parent="car"></ref>
        </property>
    </bean>

</beans>

CarBean.xml配置文件（子容器）

<?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">

    <!--Car-->
    <bean id="car" class="com.yl.bean.Car">
        <property name="brand" value="蘭博基尼"></property>
        <property name="color" value="紅色"></property>
        <property name="price" value="1000000"></property>
    </bean>

</beans>

4、測試類

 public static void main(String[] args) {
        //父容器 (CarBean)
        ApplicationContext parentCtx=new ClassPathXmlApplicationContext("CarBean.xml");
        //子容器(BoosBean)關聯父容器
        ApplicationContext childCtx=new ClassPathXmlApplicationContext(new String[] {"BossBean.xml"},parentCtx);

        Boss boss= (Boss) childCtx.getBean("boss");
        System.out.println("老板名 ="+boss.getName());
        System.out.println("所用的車 ="+boss.getCar().getBrand());
    }