1. Spring 的开发步骤

1. 导入坐标
2. 创建 Bean
3. 创建 applicationContext.xml
4. 在配置文件中进行配置
5. 创建 ApplicationContext 对象 getBean

2. 代码实现

目录结构： pom.xml 文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <packaging>war</packaging>

    <groupId>com.itheima</groupId>
    <artifactId>itheima_spring_ioc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>13</source>
                    <target>13</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

UserDao：

package com.itheima.dao;

public interface UserDao {
          
   
    public void save();
}

UserDaoImpl：

package com.itheima.dao.impl;

import com.itheima.dao.UserDao;

public class UserDaoImpl implements UserDao {
          
   
    public void save() {
          
   
        System.out.println("save running...");
    }
}

applicationContext.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">
    <!--
    xmlns 即 xml namespace xml 使用的命名空间
    xmlns:xsi 即 xml schema instance xml 遵守的具体规范
    xsi:schemaLocation 本文档 xml 遵守的规范 官方指定
    -->
    <bean id="userDao" class="com.itheima.dao.impl.UserDaoImpl"></bean>
</beans>

UserDaoDemo：

package com.itheima.damo;

import com.itheima.dao.UserDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UserDaoDemo {
          
   
    public static void main(String[] args){
          
   
        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao) app.getBean("userDao");
        userDao.save();
    }
}