如果同时存在application.yml与application.yaml会优先读取application.yml。

application.yml文件

num: 111
str: 111

other:
  dns: students.xin


schoolmate:
  - 小明
  - 小红
  - 小张

方法一，注解的方式读取application.yml文件的内容

@RestController
@RequestMapping("/books")
public class BooksController {

    @Value("${num}")
    Integer num;

    @Value("${str}")
    String str;

    @Value("${other.dns}")
    String dns;

    @Value("${schoolmate[0]}")
    String index_1;

    @RequestMapping("/xin")
    public String getById(@RequestParam("id") Integer id) {
        System.out.println(num + "--------" + str + "----------" + dns + "-----------" + index_1);
        System.out.println("id==" + id);
        return "hello spring boot";
    }
}

方法二、使用工具类的方式读取application.yml文件

@RestController
@RequestMapping("/books")
public class BooksController {
    @Autowired
    Environment environment;

    @RequestMapping("/xin")
    public String getById(@RequestParam("id") Integer id) {
        System.out.println(environment.getProperty("num"));
        System.out.println(environment.getProperty("other.dns"));
        System.out.println(environment.getProperty("schoolmate[0]"));
        System.out.println("id==" + id);
        return "hello spring boot";
    }
}

用类去读取对应的属性

application.yml文件

object:
  name: xin
  age: 111
  phone: 110
  subject:
    - 数学
    - 英语
    - 语文

创建对应实体类，加上@Component和@ConfigurationProperties注解后application.yml数据会自动写入到实体类中（前提是类是从Spring中获取的）。

@Component
@ConfigurationProperties(prefix = "student")
public class Student {
    String name;
    Integer age;
    String phone;
    String[] subject;

    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;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String[] getSubject() {
        return subject;
    }

    public void setSubject(String[] subject) {
        this.subject = subject;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", phone='" + phone + '\'' +
                ", subject=" + Arrays.toString(subject) +
                '}';
    }
}

打印

@RestController
@RequestMapping("/books")
public class BooksController {

    @Autowired
    Student student;

    @RequestMapping("/xin")
    public String getById() {
        System.out.println("------------" + student);
        return "hello spring boot";
    }
}