spring 配置bean－自己主动装配

概要：（蓝色为本节所讲）

XML配置里的Bean自己主动装配

• Spring IOC容器能够自己主动装配Bean。

  须要做的仅仅是在<bean>的autowire属性里指定自己主动装配的模式

• byType(依据类型自己主动装配)：若IOC容器中有多个与目标Bean类型一致的Bean，这样的情况下，Spring将无法推断哪个Bean最合适该属性，所以不能运行自己主动装配
• byName(依据名称自己主动装配)：必须将目标Bean的名称和属性名设置的全然同样
• constructor(通过构造器自己主动装配)：当Bean中存在多个构造器时，此种自己主动装配方式将会非常复杂。不推荐使用

代码实例具体解释：

文件夹结构：（仅仅用到com.coslay.beans.autowire）

Address.java

package com.coslay.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 + "]";
	}

}

Car.java

package com.coslay.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.coslay.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
				+ "]";
	}

}

Main.java

package com.coslay.beans.autowire;

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

public class Main {
	public static void main(String[] args) {
		ApplicationContext ctx = new ClassPathXmlApplicationContext(
				"beans-autowire.xml");

		Person person = (Person) ctx.getBean("person");
		System.out.println(person);
	}
}

<?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.coslay.beans.autowire.Address" p:city="Beijing" p:street="HuiLongGuan"></bean>	
	
	<bean id="car" class="com.coslay.beans.autowire.Car" p:brand="Audi" p:price="30000"></bean>
	
	<!-- <bean id="person" class="com.coslay.beans.autowire.Person" p:name="Tom" p:address-ref="address" p:car-ref="car"></bean> -->
	
	<!-- 
		能够使用autowire属性指定自己主动装配的方式
		byName依据bean的名字和当前bean的setter风格的属性名进行自己主动装配，若有匹配的，则进行自己主动装配，若没有匹配的。则不装配 
		byType依据bean的类型和当前bean的属性的类型进行自己主动装配.若IOC容器中有一个以上的类型匹配的bean，则抛异常		
	-->
	<bean id="person" class="com.coslay.beans.autowire.Person" p:name="Tom" autowire="byType"></bean>
</beans>