传统JavaWeb开发的困惑

IoC、DI和Aop思想提出

Spring框架的诞生

Spring 框架概述

Spring 框架历史

Spring Framework技术栈图示

BeanFactory 快速入门

1. 导入jar包

       <dependencies>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-context</artifactId>
               <version>5.3.7</version>
           </dependency>
           <dependency>
               <groupId>junit</groupId>
               <artifactId>junit</artifactId>
               <version>4.12</version>
               <scope>test</scope>
           </dependency>
       </dependencies>
   

2. 定义UserService、UserDao接口及其各自的实现类

   package com.xxxx.lln.service;
   
   /**
    * UserService接口
    */
   public interface UserService {
       public void print();
   }
   
   
   
   
   
   package com.xxxx.lln.service.serviceImpl;
   
   import com.xxxx.lln.dao.UserDao;
   import com.xxxx.lln.dao.daoImpl.UserDaoImpl;
   import com.xxxx.lln.service.UserService;
   /**
    * UserService接口实现类
    */
   public class UserServiceImpl implements UserService {
       private UserDao userDao = new UserDaoImpl();
       @Override
       public void print() {
           System.out.println("userService...");
           userDao.print();
       }
   }
   

   package com.xxxx.lln.dao;
   
   /**
    * UserDao接口
    */
   public interface UserDao {
   
       public void print();
   
   }
   
   
   
   package com.xxxx.lln.dao.daoImpl;
   
   import com.xxxx.lln.dao.UserDao;
   
   /**
    * UserDao接口实现类
    */
   public class UserDaoImpl implements UserDao {
       @Override
       public void print() {
           System.out.println("userDao...");
       }
   }
   

3. 配置xml文件

   <?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="userService" class="com.xxxx.lln.service.serviceImpl.UserServiceImpl"></bean>
       <bean id="userDao" class="com.xxxx.lln.dao.daoImpl.UserDaoImpl"></bean>
   
   </beans>
   

4. 创建BeanFactoryTest，加载配置文件，获取UserService

   package com.xxxx.lln.test;
   
   import com.xxxx.lln.dao.UserDao;
   import com.xxxx.lln.service.UserService;
   import org.junit.jupiter.api.Test;
   import org.springframework.beans.factory.support.DefaultListableBeanFactory;
   import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
   
   public class BeanFactoryTest {
   
       @Test
       public void test1() {
   
           //创建工厂对象
           DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
           //创建一个读取器（xml文件）
           XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
           //读取器配置文件给工厂
           reader.loadBeanDefinitions("bean1.xml");
           //根据id获取Bean实例对象
           UserService userService = (UserService) beanFactory.getBean("userService");
           System.out.println(userService);
           userService.print();
           UserDao userDao = (UserDao) beanFactory.getBean("userDao");
           System.out.println(userDao);
           userDao.print();
   
       }
   }
   
   

   

DI 入门案例

Spring的IOC入门案例已经完成，但是在UserServiceImpl的类中依然存在UserDaoImpl对象的new操作，它们之间的耦合度还是比较高，这块该如何解决，就需要用到下面的DI:依赖注入。

1. 删除业务层中使用new的方式创建的dao对象，提供userDao的setter方法

   package com.xxxx.lln.service.serviceImpl;
   
   import com.xxxx.lln.dao.UserDao;
   import com.xxxx.lln.dao.daoImpl.UserDaoImpl;
   import com.xxxx.lln.service.UserService;
   import com.xxxx.lln.test.BeanFactoryTest;
   
   /**
    * UserService接口实现类
    */
   public class UserServiceImpl implements UserService {
   
       //private UserDao userDao = new UserDaoImpl();
       private UserDao userDao;
       public void setUserDao(UserDao userDao){
           System.out.println("BeanFactoryTest调用setUserDao该方法"+userDao);
           this.userDao = userDao;
       }
   
       @Override
       public void print() {
           System.out.println("userService...");
           userDao.print();
       }
   }
   
   

2. 在配置文件中添加依赖注入的配置

       <bean id="userService" class="com.xxxx.lln.service.serviceImpl.UserServiceImpl">
           <property name="userDao" ref="userDao"></property>
       </bean>
       <bean id="userDao" class="com.xxxx.lln.dao.daoImpl.UserDaoImpl"></bean>
   

3. 运行程序调用方法
   

ApplicationContext快速入门

package com.xxxx.lln.test;

import com.xxxx.lln.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class ApplicationContextTest {

    @Test
    public void test1() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean1.xml");
        UserService userService = (UserService) applicationContext.getBean("userService");
        System.out.println(userService);
    }

}

BeanFactory 和 ApplicationContext的关系

BeanFactory 的继承体系

ApplicationContext 的继承体系

基于xml的Spring应用

SpringBean 的配置详解

基于注解的Spring应用