测试的环境：Spring Boot2 + Maven +lombok

准备需要用到的基础类：

public class People {
    private String name;
    private String address;
    private String phone;
}

准备默认的配置文件application.properties，内容如下

people.default.name=zs
people.default.address=ccc
people.default.phone=122122

准备自定义配置文件people.properties，内容如下

people.default.name=test-zs
people.default.address=test-address
people.default.phone=111111

准备测试类

@RestController
public class PeopleController {

    @Autowired
    private People people;

    @RequestMapping("/test1")
    public void test1(){
        System.out.println(people);
    }
}

第一种情况：读取默认配置文件中的自定义属性（如application.properties）

1、直接在指定类读取文件属性

@Data
//@Setter
@ToString
@Configuration
@ConfigurationProperties(prefix = "people.default")
public class People {
    private String name;
    private String address;
    private String phone;
}

 注意：类用到了lombok的注解（@Data）或者使用@Setter注解。所以有getter/setter。如果没有使用注解，则需要setter方法才能读取成功。

2、配合@Vaule读取文件属性

@Configuration
public class PeopleConfigrution {

    @Value("${people.default.name}")
    private String name;
    @Value("${people.default.address}")
    private String address;
    @Value("${people.default.phone}")
    private String phone;

    @Bean
    public People initPeople(){
        People people=new People();
        people.setName(name);
        people.setPhone(phone);
        people.setAddress(address);
        return people;
    }
}

 3、使用Environment读取

@Configuration
public class PeopleConfigrution {

    @Autowired
    private Environment environment;

    @Bean
    public People initPeople(){
        People people=new People();
        people.setName(environment.getProperty("people.default.name"));
        people.setPhone(environment.getProperty("people.default.phone"));
        people.setAddress(environment.getProperty("people.default.address"));
        return people;
    }
}

第二种情况：读取自定义文件中的属性(如people.properties)

需指定读取文件的位置,可使用@PropertySource注解指定，如

@Data
//@Setter
@ToString
@Configuration
@PropertySource("classpath:people.properties")  //指定读取文件位置，可与读取默认文件第一种方式相比。
@ConfigurationProperties(prefix = "people.default")
public class People {
    private String name;
    private String address;
    private String phone;
}

 以上列举的不是全部方式，加载文件的方式还有其他方式，这篇只是列举常用的方式。