下面搭建一下纯净版的spring5环境，主要实现的功能是配置文件和注解方式获取bean，代码例子如下：

一、依赖pom.xml中

<!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>

二、带配置文件版

1、配置文件applicationContext.xml

这里需要支持注解模式

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">
    <!--编写对应的配置信息-->
     <bean class="com.suibibk.spring.entity.User" id="user"/>
     <!-- 开启注解 -->
     <context:component-scan base-package="com.suibibk.spring"/>
</beans>

注意：若要支持注解模式，头文件里需要有如下内容：

xmlns:context="http://www.springframework.org/schema/context"
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd

2、bean对象Car和User

User是用配置文件的方式初始化bean，Car是用注解的方式初始化bean。

package com.suibibk.spring.entity;
public class User {
    private String username;
    private int age;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [username=" + username + ", age=" + age + "]";
    }
}

package com.suibibk.spring.entity;
import org.springframework.stereotype.Component;
@Component
public class Car {
    private String carName;
    public String getCarName() {
        return carName;
    }
    public void setCarName(String carName) {
        this.carName = carName;
    }
    @Override
    public String toString() {
        return "Car [carName=" + carName + "]";
    }
}

可以看到，Car上有注解@Component

3、测试类

public class App {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        //获取上下文对象ApplicationContext
        ApplicationContext context = new  ClassPathXmlApplicationContext("applicationContext.xml");
        //获取实例,配置文件
        User user = (User)context.getBean("user");
        user.setUsername("suibibk.com");
        user.setAge(18);
        System.out.println(user);
        //获取实例，注解
        Car car = (Car)context.getBean("car");
        car.setCarName("宝马");
        System.out.println(car);
    }
}

4、结果

User [username=suibibk.com, age=18]
Car [carName=宝马]

三、纯注解版

现在一般都不用配置文件的方式，直接注解即可。

1、配置文件类

@Configuration
@ComponentScan(basePackages = "com.suibibk.spring")
public class SpringConfiguration {
    //spring容器初始化时，会调用配置类的无参构造函数
    public SpringConfiguration(){
        System.out.println("容器启动初始化");
    }
}

2、User

@Component
public class User {
    private String userName;
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    @Override
    public String toString() {
        return "User [userName=" + userName + "]";
    }
}

User需要在配置文件类的扫描包下面

3、测试类

public class App {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfiguration.class);
        User user = (User) context.getBean("user");
        user.setUserName("个人随笔");
        System.out.println(user);
    }
}

4、运行结果

容器启动初始化
User [userName=个人随笔]

完成。