Spring(三)Spring三种实例化JavaBean的方式

Spring实例化JavaBean的方式有三种：使用类构造器实例化、使用静态工厂方法实例化、使用实例化工厂实例化

package test.spring.service;

public interface PersonService {

	public abstract void save();

}

package test.spring.service.impl;

import test.spring.service.PersonService;

public class PersonServiceBean implements PersonService {

	@Override
	public void save(){
		System.out.println("=============");
	}
}

package test.spring.service.impl;

public class PersonServiceBeanFactory {
	// 静态工厂方法
	public static PersonServiceBean createPersonServiceBean() {
		return new PersonServiceBean();
	}

	// 实例工厂方法
	public PersonServiceBean createPersonServiceBean2() {
		return new PersonServiceBean();
	}
}

使用实例化工厂方法需先配置工厂类，再配置工厂方法。用得最多的是第一种。

<?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-2.5.xsd">

	<!-- 这时候这个bean就可以由spring帮我们创建和维护，用到时只需从spring容器中获取 -->
	<bean id="personService" class="test.spring.service.impl.PersonServiceBean"></bean>
	<bean id="personService2" class="test.spring.service.impl.PersonServiceBeanFactory"
		factory-method="createPersonServiceBean"></bean>
	<bean id="personServiceFactory" class="test.spring.service.impl.PersonServiceBeanFactory"></bean>
	<bean id="personService3" factory-bean="personServiceFactory"
		factory-method="createPersonServiceBean2"></bean>

</beans>

package test.spring.jnit;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import test.spring.service.PersonService;

public class SpringTest {

	@Test
	public void testInstanceSpring() {
		// ApplicationContext applicationContext = new
		// ClassPathXmlApplicationContext(
		// new String[] { "beans.xml" });

		//使用类构造器实例化，用的是默认构造函数
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
				"beans.xml");

		// PersonService personService = (PersonService) applicationContext
		// .getBean("personService");// 得到的是Object,需进行转换

		// BeanManageTest beanManageTest = new BeanManageTest("beans.xml");
		// PersonService personService = (PersonService) beanManageTest
		// .getBean("personService");// 得到的是Object,需进行转换

		// 使用静态工厂方法实例化
		// PersonService personService = (PersonService) applicationContext
		// .getBean("personService2");

		// 使用实例化工厂实例化
		PersonService personService = (PersonService) applicationContext
				.getBean("personService3");
		personService.save();
	}

}

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