Three Ways to Read YML Config in SpringBoot: @Value, Environment & @ConfigurationProperties

Project Setup

Create a SpringBoot project via Spring Initializr with the Spring Web dependency. The example uses Spring Boot 2.6.10 and Java 8. The pom.xml includes spring-boot-starter-web, spring-boot-starter-test, and the optional spring-boot-configuration-processor to enable IDE hints for @ConfigurationProperties.

YML Configuration File

SpringBoot loads application.yml (or .yaml / .properties) from src/main/resources. Priority order: properties > yml > yaml. Key YML rules: case-sensitive keys, values require at least one space after the colon, indentation defines hierarchy (spaces only, no tabs), # starts a comment.

Example application.yml:

name: 候胖胖
age: 40
hobby: 瞎逛游,开玩笑,踢毽子
employee:
  name: 任肥肥
  age: 38
  hobby:
    - 睡觉
    - 吃饭
    - 摸鱼
remark1: '${name} 
 喜欢踢毽子'
remark2: "${employee.name} 
 喜欢上班摸鱼"

Note: single quotes disable escape processing; double quotes enable it. Property references like ${name} and ${employee.name} are resolved.

Method 1: @Value Annotation

Inject individual properties directly into fields using @Value("${property.path}"). Works for primitives, Strings, and comma-separated strings converted to arrays. Cannot bind a YML list (dash syntax) as a whole array — only individual elements via index (e.g., ${employee.hobby[0]}).

@Value("${name}")
private String name;
@Value("${age}")
private int age;
@Value("${hobby}")
private String[] hobby; // comma-separated string -> array
@Value("${employee.name}")
private String e_name;
@Value("${employee.age}")
private int e_age;
@Value("${employee.hobby[0]}")
private String e_hobby0;

Endpoint /getdata1 returns concatenated values.

Method 2: Environment Abstraction

Autowire org.springframework.core.env.Environment and call getProperty(String key). Retrieves any property by its full path. Also resolves property references and escape sequences exactly as defined in YML.

@Autowired
private Environment env;

String name2 = env.getProperty("name");
String e_name2 = env.getProperty("employee.name");
String remark1 = env.getProperty("remark1"); // single-quoted: literal 

String remark2 = env.getProperty("remark2"); // double-quoted: actual newline

Endpoint /getdata2 prints results to console.

Method 3: @ConfigurationProperties Binding

Create a POJO annotated with @Component and @ConfigurationProperties(prefix = "employee"). Fields matching the nested YML structure (name, age, hobby) are bound automatically, including dash-style lists into arrays/collections.

@Component
@ConfigurationProperties(prefix = "employee")
public class Employee {
    private String name;
    private int age;
    private String[] hobby;
    // getters, setters, toString
}

Inject the bean and access typed properties. Endpoint /getdata3 prints the full object.

IDE Support

Adding spring-boot-configuration-processor (optional) eliminates the red warning banner in IntelliJ IDEA and provides autocomplete for configuration keys in YML files.

Running the Demo

Start the application (default port 8080). Test endpoints: GET /getdata1 — @Value results GET /getdata2 — Environment results (check console) GET /getdata3 — @ConfigurationProperties results (check console)

Change port via server.port: 8888 in YML.