How to get the content of file properties in Spring Boot

Question

As the title, my custom properties:

#app settings
my.chassisNum=10

java code:

@PropertySource("classpath:appconf.properties")
@ConfigurationProperties(prefix = "my" )
@Component
public class AppConfig {

    private String chassisNum;

    public String getChassisNum() {
        return this.chassisNum;
    }

    public void setChassisNum(String chassisNum) {
        this.chassisNum = chassisNum;
    }
}

when Spring Boot start completed, I got the "chassisNum" value is 10. when I got it in other place when spring-boot not start completed, it get "null"

@Component
public class CreateBaseFolder {

    private final Logger logger = LogManager.getLogger(CreateBaseFolder.class);
    private File f; 
    @Autowired
    AppConfig appconf;

    public CreateBaseFolder() {

        System.out.println(appconf.getChassisNum());


    } 

i try many way to get it value,but is false.such as :implements InitializingBean, @DependsOn....

Answer 1

Assume you has application.properties with content:

foo.bar=Jerry

You will use annotation @Value

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class GetPropertiesBean {

    private final String foo;

    @Autowired
    public GetPropertiesBean(@Value("${foo.bar}") String foo) {
        this.foo = foo;
        System.out.println(foo);
    }

}

Of course, we need an entry point

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

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

}

Then run class Application as Spring Boot application, component is autoload, you will see result at console screen

Jerry