使用实例化工厂方法实例化bean

使用实例化工厂方法实例化bean，使用这种方法不能指定class属性，此时必须使用factory-bean属性来指定工厂bean，factory-method属性指定实例化bean的方法，而且使用实例化工厂方法允许指定方法参数，方式和使用构造器方法一样。

package org.spring.chapter2.helloworld;

public class HelloImpl2 implements HelloApi {

	private String message;
	
	public HelloImpl2() {
		this.message="Hello World in Empty Constructor";
	}

	public HelloImpl2(String message) {
		this.message = message;
	}

	@Override
	public void sayHello() {
		System.out.println(message);
	}

}

package org.spring.chapter2.helloworld;

public class HelloApiInstanceFactory {

	public  HelloApi newInstance(String message){
		return new HelloImpl2(message);
	}
}

<?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:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans   
	     				http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
						http://www.springframework.org/schema/context           
     					http://www.springframework.org/schema/context/spring-context-3.0.xsd">
	<!-- id 表示你这个组件的名字，class表示组件类 -->
	<!-- 实例化工厂bean -->
	<bean id="beanInstanceFactory" class="org.spring.chapter2.helloworld.HelloApiInstanceFactory" />
	
	<!-- 使用实例化工厂bean创建bean -->
	<bean id="bean4" class="org.spring.chapter2.helloworld.HelloApiInstanceFactory" 
	factory-bean="beanInstanceFactory" factory-method="newInstance">
	  <constructor-arg index="0" value="Hello Spring"></constructor-arg>
	</bean>
</beans>

@Test
	public void testInstanceFactory(){
		ApplicationContext context = new ClassPathXmlApplicationContext("org/spring/chapter2/helloworld/helloworld4.xml");
		HelloApi bean4 = context.getBean("bean4",HelloApi.class);
		System.out.println("------------实例化工厂-----------------------");
		bean4.sayHello();
	}