Spring中Bean實例化的方式

有三種方式：類構造器，靜態工廠，實例工廠。後兩種通過調用第一個實現。

1. 類構造器

Bean:

public Class Person(){
	private String name;
	private Integer age;
	public Person(){}
	public Person(String name,Integer age){
		this.name = name;
		this.age =age;
	}
}

applicationContext.xml

//1. 無參
<bean id="person1" class="com.imooc.spring.instance.Person" />

//2. 有參
<bean id="person2" class="com.imooc.spring.instance.Person" >
	<constructor-arg name="name" value="楓葉" />
	<constructor-arg name="age" value=23 />
</bean>

main

ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:applicationContext.xml)

2. 靜態工廠

public class PersonStaticFactory{
	public static Person createPerson(String name, Integer age){
		return new Person(name,age);
	}
}

xml:

<bean id="person3" class="com.imooc.spring.instance.PersonStaticFactory factory-method="createPerson">
	<constructor-arg name="name" value="藍天" />
	<constructor-arg name="age" value=27 />
</bean>

main

ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:applicationContext.xml)

3. 實例工廠

相比於靜態工廠，在工廠方法上少了static，需要在xml中先實例化工廠方法，再實例對象。