Spring-factory class structure

1.1 Project structure

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1.2 Illustration of factory architecture

1.3 Interface difference

The difference between BeanFactory and ApplicationContext

BeanFactory是顶层接口,ApplicationContext是子接口。

The biggest difference between them isThe time to create the object is different

• BeanFactory uses the idea of ​​lazy loading. That is, when to use the object and when to create it .
• ApplicationContext adopts the idea of ​​immediate creation.That is, as soon as the configuration file is loaded, it is created immediately。

1.4 Code example

Persistence layer (Dao layer)

dao interface

package cn.guardwhy.dao;
/**
 * 客户dao接口
 */
public interface CustomerDao {
    
    
    /**
     * 保存客户操作
     */
    void saveCustomer();
}

dao implementation class

package cn.guardwhy.dao.impl;

import cn.guardwhy.dao.CustomerDao;

/**
 * 客户dao实现类
 */
public class CustomerDaoImpl implements CustomerDao {
    
    
    @Override
    public void saveCustomer() {
    
    
        System.out.println("保存客户操作");
    }
}

Service

service interface

package cn.guardwhy.service;
/**
 * 客户service接口
 */
public interface CustomerService {
    
    
    /**
     * 保存客户操作
     */
    void saveCustomer();
}

service implementation class

package cn.guardwhy.service.impl;

import cn.guardwhy.dao.CustomerDao;
import cn.guardwhy.dao.impl.CustomerDaoImpl;
import cn.guardwhy.service.CustomerService;
/**
 * 客户service实现类
 */
public class CustomerServiceImpl implements CustomerService {
    
    
    // 定义客户dao
    private CustomerDao customerDao = new CustomerDaoImpl();

    /**
     * 保存客户操作
     */
    @Override
    public void saveCustomer() {
    
    
        customerDao.saveCustomer();
    }
}

Write bean.xml

<?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">
    <!--配置service，说明：
       标签：
           bean：配置javaBean对象
       属性：
           id：bean的唯一标识名称
           class：类的全路径信息
       细节：默认使用无参数构造方法，创建对象
    -->
    <bean id="customerService" class="cn.guardwhy.service.impl.CustomerServiceImpl"></bean>

    <!--配置dao-->
    <bean id="customerDao" class="cn.guardwhy.dao.impl.CustomerDaoImpl"></bean>
</beans>

Presentation layer (Controller)

ApplicationContext

package cn.guardwhy.controller;

import cn.guardwhy.service.CustomerService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 客户controller
 */
public class CustomerController {
    
    
    public static void main(String[] args) {
    
    
        /**
          BeanFactory与ApplicationContext区别：
          1.BeanFactory是顶层接口
          2.ApplicationContext是子接口
          3.它们的区别是创建对象的时间点不一样：
            a、BeanFactory采用延迟加载的思想。即什么时候使用对象，什么时候创建
            b、ApplicationContext采用立即创建的思想。即一加载spring配置文件，立即就创建对象
         */

        // 1.加载spring配置文件，创建spring ioc容器
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        // 2.打印容器创建完成的信息
        System.out.println("-----------------start");
        System.out.println("spring IOC容器创建好了");
        System.out.println("----------------end");
        // 2.从容器中获取客户service对象
        CustomerService customerService = (CustomerService) context.getBean("customerService");
        // 3.保存客户
        customerService.saveCustomer();
    }
}

Results of the

Presentation layer (Controller)

BeanFactory

package cn.guardwhy.controller;

import cn.guardwhy.service.CustomerService;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

/**
 * 客户controller
 */
public class CustomerController {
    
    
    public static void main(String[] args) {
    
    
        /**
          BeanFactory与ApplicationContext区别：
          1.BeanFactory是顶层接口
          2.ApplicationContext是子接口
          3.它们的区别是创建对象的时间点不一样：
            a、BeanFactory采用延迟加载的思想。即什么时候使用对象，什么时候创建
            b、ApplicationContext采用立即创建的思想。即一加载spring配置文件，立即就创建对象
         */

       // 1.创建资源对象
        Resource resource = new ClassPathResource("bean.xml");
        BeanFactory context = new XmlBeanFactory(resource);

        // 2.打印容器创建的信息
        System.out.println("------------------start");
        System.out.println("spring IOC容器创建好了");
        System.out.println("-----------------end");

        // 3.从容器中获取客户service对象
        CustomerService customerService = (CustomerService) context.getBean("customerService");
        // 4.保存客户
        customerService.saveCustomer();
    }
}

Results of the