【尚硅谷】spring学习笔记（4）：XML 配置里的 Bean 自动装配

XML 配置里的 Bean 自动装配

• 在 Bean 配置文件里设置 autowire 属性进行自动装配将会装配 Bean 的所有属性. 然而, 若只希望装配个别属性时, autowire 属性就不够灵活了. 
• autowire 属性要么根据类型自动装配, 要么根据名称自动装配, 不能两者兼而有之.
• 一般情况下，在实际的项目中很少使用自动装配功能，因为和自动装配功能所带来的好处比起来，明确清晰的配置文档更有说服力一些

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="address" class="com.atguigu.spring.beans.autowire.Address" p:city="北京" p:street="朝阳街"></bean>
    <bean id="car" class="com.atguigu.spring.beans.autowire.Car" p:brand="吉利" p:price="20000"></bean>
    <!--<bean id="person" class="com.atguigu.spring.beans.autowire.Person" p:name="小明" p:address-ref="address" p:car-ref="car"></bean> -->
    
    <!-- 可以使用autowire属性自动装配，byName根据setter名字和bean的名字进行匹配装配  
         byType根据bean的类型和当前bean的属性的类型进行自动装配
    -->
    <bean id="person" class="com.atguigu.spring.beans.autowire.Person" p:name="小明" autowire="byName"></bean>
</beans>

package com.atguigu.spring.beans.autowire;

public class Person {
	private String name;
	
	private Address address;
	
	private Car car;

	public String getName() {
		return name;
	}

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

	public Address getAddress() {
		return address;
	}

	public void setAddress(Address address) {
		this.address = address;
	}

	public Car getCar() {
		return car;
	}

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

	@Override
	public String toString() {
		return "Person [name=" + name + ", address=" + address + ", car=" + car + "]";
	} 	
}

package com.atguigu.spring.beans.autowire;

public class Address {
	
	private String city;
	private String street;
	
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getStreet() {
		return street;
	}
	public void setStreet(String street) {
		this.street = street;
	}
	@Override
	public String toString() {
		return "Address [city=" + city + ", street=" + street + "]";
	}
}

package com.atguigu.spring.beans.autowire;

public class Car {

	private String brand;
	private double price;
	
	public String getBrand() {
		return brand;
	}
	public void setBrand(String brand) {
		this.brand = brand;
	}
	public double getPrice() {
		return price;
	}
	public void setPrice(double price) {
		this.price = price;
	}
	
	@Override
	public String toString() {
		return "Car [brand=" + brand + ", price=" + price + "]";
	}	
}

package com.atguigu.spring.beans.autowire;

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

public class Main {
	public static void main(String[] args) {
	ApplicationContext apc = new  ClassPathXmlApplicationContext("beans-autowire.xml");
	Person person = (Person) apc.getBean(Person.class);
	System.out.println(person);
	
	}

}

结果：

六月 08, 2018 10:35:29 上午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6193b845: startup date [Fri Jun 08 10:35:29 CST 2018]; root of context hierarchy
六月 08, 2018 10:35:29 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-autowire.xml]
Person [name=小明, address=Address [city=北京, street=朝阳街], car=Car [brand=吉利, price=20000.0]]