Properties 檔案中可以引用屬性來賦值：

app.name=MyApp
app.name=MyApp app.description=${app.name} is a Spring Boot application

也可以引入系統變數的值

spring.cloud.stream.bindings.process-in-0.group=user_${HOSTNAME:localhost}

另外也可以設定一些隨機值

my.secret=${random.value}
my.number=${random.int}
my.bignumber=${random.long}
my.uuid=${random.uuid}
my.number-less-than-ten=${random.int(10)}
my.number-in-range=${random.int[1024,65536]}

　用properties檔案也可以設定map值

secret.mapper.john=johnpwd
secret.mapper.lisa=lisapwd
secret.mapper.marry=marrypwd

@SpringBootApplication
@EnableConfigurationProperties(SecretKey.class)
public class UserInfoApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserInfoApplication.class, args);
    }

}



@ConfigurationProperties(prefix = "secret")
public class SecretKey {
    private final Map<String, String> mapper = new ConcurrentHashMap<>();

    public Map<String, String> getMapper() {
        return mapper;
    }
}

參考文件：

https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-external-config