如何使用 IoC

• 创建Maven工程，pom.xml添加依赖

<?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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.min</groupId>
    <artifactId>Spring-Study</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.11.RELEASE</version>
        </dependency>
    </dependencies>

</project>

• 创建实体类 Student

package com.min.entity;

import lombok.Data;

@Data
public class Student {
    private long id;
    private String name;
    private int age;
}

• 传统的开发方式，手动 new Student

Student student = new Student();
student.setId(1L);
student.setName("张三");
student.setAge(22);
System.out.println(student);

• 通过 IoC 创建对象，在配置文件中添加需要管理的对象，XML 格式的配置文件，文件名可以自定义。

<?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"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">

    <bean id="student" class="com.southwind.entity.Student">
        <property name="id" value="1"></property>
        <property name="name" value="张三"></property>
        <property name="age" value="22"></property>
    </bean>
</beans>

• 从 IoC 中获取对象，通过 id 获取。

//加载配置文件
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
Student student = (Student) applicationContext.getBean("student");
System.out.println(student);