Spring框架中Bean的三种配置和实例化方法总结

package com.example.dao;
public interface BookDao {
    public void save();
}

package com.example.dao.impl;
import com.example.dao.BookDao;
public class BookDaoimpl implements BookDao {
    public void save(){
        System.out.println("玛卡巴卡");
    }
}

<?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.xsd">
    <bean id="bookDao" class="com.example.dao.impl.BookDaoimpl"/>
</beans>

package com.example.dao.factory;
import com.example.dao.BookDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppForInstanceBook {
    public static void main(String[] args) {
        ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        BookDao bookDao=(BookDao) ctx.getBean("bookDao");
        bookDao.save();
    }
}

package com.example.dao.factory;
public class OrderDaoFactory {
    public static OrderDaoimpl getOrderDao(){
        return new OrderDaoimpl();
    }
}

<?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.xsd">
<!--    <bean id="orderDao" class="com.example.dao.impl.BookDaoimpl"/>-->
        <bean id="bookDao" class="com.example.dao.factory.OrderDaoFactory" factory-method="getOrderDao"/>
</beans>

package com.example.dao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppForInstanceOrder {
    public static void main(String[] args) {
        ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        OrderDao orderDao=(OrderDao) ctx.getBean("orderDao");
        orderDao.save();
    }
}