@Value注解

1.注入 基本字符 

public class Student {
    @Value("qq")
    private String name;
    @Value("12")
    private Integer age;

2.el表达式 

public class Student {
    @Value("qq")
    private String name;
    @Value("#{20-2}")
    private Integer age;

3.读取配置文件 

配置文件 

student.name=Martin

  配置类  

@Configuration
@PropertySource(value = "classpath:/app.properties")
public class Config {

    @Bean
    public Student student(){
        return new Student();
    }

}

  Bean类 

public class Student{
    @Value("${student.name}")
    private String name;

    private Integer age;