spring源码 @Value赋值，属性信息是保存在运行环境变量里面简单示例

通过@Value读取属性的值

新建maven，pom如下

<dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-context</artifactId>
       <version>5.0.6.RELEASE</version>
</dependency>
新建bean

public class Bird {
    @Value("张三")
    private String name;
    @Value("#{23-1}")
    private Integer age;
    @Value("${bird.color}")
    private String color;
 
    public Bird() {
    }
 
    public Bird(String name, Integer age) {
        this.name = name;
        this.age = age;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public Integer getAge() {
        return age;
    }
 
    public void setAge(Integer age) {
        this.age = age;
    }
 
    @Override
    public String toString() {
        return "Bird{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", color='" + color + '\'' +
                '}';
    }
}
在resources新建test.perperties

bird.color=red
新建config配置类，并加载属性文件

@Configuration
@PropertySource(value = {"classpath:/test.properties"})
public class DemoConfig {
 
    @Bean
    public Bird bird() {
        return new Bird();
    }
}
新建启动类

public class DemoApp {
    public static void main(String[] args){
        AnnotationConfigApplicationContext app = new AnnotationConfigApplicationContext(DemoConfig.class);
        System.out.println("IOC容器初始化完成");
        String[] names = app.getBeanDefinitionNames();
        for (int i = 0; i < names.length; i++) {
            String name = names[i];
            System.out.println(name);
 
        }
        Bird bean = (Bird)app.getBean("bird");
        System.out.println(bean);
 
//属性信息是保存在运行环境变量里面
        ConfigurableEnvironment environment = app.getEnvironment();
        String color = environment.getProperty("bird.color");
        System.out.println("environment:"+color);
        app.close();
    }
}
输出结果：

IOC容器初始化完成
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
demoConfig
bird
Bird{name='张三', age=22, color='red'}
red