SpringBoot 使用一个全局的配置文件，名字固定

application.properties  语法结构：key=value

application.yml  语法结构：key：（空格）value

配置文件的作用是可以修改 SpringBoot 自动配置的默认值

在 resources 目录下创建 application.yml

server:
  port: 8080

properties 只能保存键值对

yaml 对空格的要求非常严苛，并且 yaml 可以注入到配置类

举个例子

Dog.java：

package com.demo.helloworld.pojo;

public class Dog {
    private String name;
    private Integer age;

    public Dog() {
    }

    public Dog(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 "Dog{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

Person.java：

@ConfigurationProperties 作用：

将配置文件中配置的每一个属性的值，映射到这个组件中

告诉 SpringBoot 将本类中的所有属性和配置文件中相关的配置进行绑定

参数 prefix = "person"  将配置文件中的 person 类下的所有属性一一对应

只有这个组件是容器中的组件，才能使用容器提供的 @ConfigurationProperties 功能

package com.demo.helloworld.pojo;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import java.util.Date;
import java.util.List;
import java.util.Map;

@Component //注册bean
@ConfigurationProperties(prefix = "person") //配置类的值与配置文件绑定
public class Person {
    private String name;
    private Integer age;
    private Boolean happy;
    private Date birthday;
    private Map<String, Object> map;
    private List<Object> list;
    private Dog dog;

    public Person() {
    }

    public Person(String name, Integer age, Boolean happy, Date birthday, Map<String, Object> map, List<Object> list, Dog dog) {
        this.name = name;
        this.age = age;
        this.happy = happy;
        this.birthday = birthday;
        this.map = map;
        this.list = list;
        this.dog = dog;
    }

    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 Boolean getHappy() {
        return happy;
    }

    public void setHappy(Boolean happy) {
        this.happy = happy;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public Map<String, Object> getMap() {
        return map;
    }

    public void setMap(Map<String, Object> map) {
        this.map = map;
    }

    public List<Object> getList() {
        return list;
    }

    public void setList(List<Object> list) {
        this.list = list;
    }

    public Dog getDog() {
        return dog;
    }

    public void setDog(Dog dog) {
        this.dog = dog;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", happy=" + happy +
                ", birthday=" + birthday +
                ", map=" + map +
                ", list=" + list +
                ", dog=" + dog +
                '}';
    }
}

application.yml：

person:
  name: 张三
  age: 18
  happy: true
  birthday: 2024/8/1
  map: {k1: v1,k2: v2}
  list:
    - sing
    - dance
  dog:
    name: dog
    age: 1

测试类：

package com.demo.helloworld;

import com.demo.helloworld.pojo.Person;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

//单元测试
@SpringBootTest
class HelloWorldApplicationTests {
    @Autowired
    private Person person;

    @Test
    void contextLoads() {
        System.out.println(person);
    }

}

也可以通过 @PropertySource(value = "classpath:xx.properties")  指定配置文件

//加载指定的配置文件
@PropertySource(value = "classpath:xx.properties")

但需要在属性上方或者 Set 方法上加 @Value 赋值

在 yaml 里可以随便使用占位符或者直接 ${random.uuid} 就能实现随机数