SpringBootApplication无法从application.yml文件加载属性

Question

Configuration class,

@Configuration
public class SpringContext {
@Bean
public BlockingQueue<String> queue(@Value("${queue.size}") int queueSize) {
    return new LinkedBlockingQueue<>();
   }
}

Main class,

@SpringBootApplication
public class SpringContextTest {

    public static void main(String[] args) {
        final SpringApplication springApplication = new SpringApplication(SpringContext.class);
        springApplication.setWebEnvironment(false);
        springApplication.run();
        System.out.println("queue.size" + System.getProperty("queue.size"));
    }

}

application.yml,

queue.size: 10

While starting the main class I'm getting the following error,

Caused by: java.lang.NumberFormatException: For input string: "${queue.size}"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_144]

I'm I missing some annotations ?, In my understanding I've used the minimal annotations required for a spring boot application. I have seen some similar posts but didn't helped. Also tried with --spring.config.location .

My Spring starter version: 1.3.6.RELEASE

Answer 1

Your config file looks more like an application.properties rather than an application.yml

queue.size: 10

The equivalent yml should be:

queue:
    size: 10

UPDATE

Yes both should work in .yml you are right. I replicated exactly your example and it worked!

Just make sure you application.yml file is in the root of the src/main/resources/ . I had the same error as yours when I had the application.yml file in a subdirectory eg src/main/resources/com/myapp/

Answer 2

The Externalized Configuration section of the Spring Boot docs, explains all the details that you might need.

As per your example to load properties in the main class you can do something like this,

1. First double check the location of the yaml file, It should be located in /src/main/resources/application.yaml

2. The content should be like the following example,

   \napp: \n    value1: 12 \n    value2: stringValue \n

3. Sample code,

   \npackage com.demo; \n\nimport org.springframework.boot.SpringApplication; \nimport org.springframework.boot.autoconfigure.SpringBootApplication; \nimport org.springframework.core.env.Environment; \n\n@SpringBootApplication \npublic class App { \n\n
    public static void main( String[] args ){ SpringApplication app = new SpringApplication(App.class); Environment env = app.run(args).getEnvironment(); String value1 = env.getProperty("app.value1"); String value2 = env.getProperty("app.value2"); System.out.println("---------------- "+value1); System.out.println("---------------- "+value2); } 
   \n\n} \n\n

Answer 3

Guesses

According to the current information you provides, I can't re-produce the problem, so the following is just some guesses:

• Check whether file name and file location of application.yml is right;

• Try use Spring EL:

   @Value("#{applicationConfig['queue.size']}") 

• Try debug property loading:

   @Bean public BlockingQueue<String> queue(ConfigurableEnvironment env) { return new LinkedBlockingQueue<>(); // set breakpoint here, to see if env has your property in PropertySource: applicationConfig } 

More

More about property source and yaml loading in my blog.

Further

If the suggestions not help, you may better

• provide a sample project that can re-produce problem;
• provide complete stacktrace;