spring IOC用ref屬性實現bean之間的引用
阿新 • • 發佈:2018-12-25
如下圖所示,用ref屬性建立bean之間的引用
<bean id="person" class="com.beans.Person"> <property name="name" value="tom"></property> <property name="age" value="20"></property> <!-- 可以使用property的ref屬性建立bean之間的引用關係--> <property name="car" ref="car2"></property> </bean>
下面是car2的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>
下面貼出整個專案的完整程式碼,可以自己新建一個專案貼上去試下。
執行主類
package com.beans; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { //1.建立spring的IOC容器物件 //ApplicationContext 代表IOC容器 是 BeanFactory 介面的子介面 // ClassPathXmlApplicationContext: 是 ApplicationContext的實現類,從類路徑下來載入配置檔案 ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml"); //2.從IOC容器中獲取bean例項 //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類
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類
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 配置檔案
<?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 的全類名,通過反射的方式在IOC容器中建立bean,所以要求必須要有無參的構造器
id: 表示容器中唯一的id
-->
<!--通過構造方法配置bean的屬性 -->
<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>
<!-- 可以使用property的ref屬性建立bean之間的引用關係-->
<property name="car" ref="car2"></property>
</bean>
</beans>
執行結果如下