CODEWITHSUNDEEP
spring
user55305
user55305

Reputation: 31

How to access a property passed by command line in Spring Boot

In our environment, the port the server listens is always specified by a command line parameter:

java -jar myweb.jar --server.port=1024.

How can we get this value? In my AppSiteController.java I tried to use:

@Value("${server.port}")
private static String serverPort;

public static void main(String[] args) {
    System.out.println(serverPort);
    SpringApplication.run(AppSiteController.class, args);
}

Which returns null when the value is correctly specified on the command line.

Thanks.

Upvotes: 3

Views: 1712

Answers (4)

user55305
user55305

Reputation: 31

After much research, I found that it is because Spring boot can't inject value into static variables. The solution is here:

Spring Boot @Value Properties

This code:

@Value("${server.port}")
private static String serverPort;

Should be this:

private static String serverPort;
@Value("${server.port}")
public void setPort(String value) {
    serverPort = value;
}

Upvotes: 0

Essex Boy
Essex Boy

Reputation: 7950

Pass it as a system parameter to the jvm

java -Dserver.port=8080 -jar spring-boot.jar

All java system parameters are added to the spring environment

Upvotes: 1

Ashish Patil
Ashish Patil

Reputation: 4624

rather than using 

@Value("${server.port}")
private static String serverPort;

consider using below in springboot application :

@Bean
    public String value(@Value("#{server.port}")String value){
        return value;
    }

And then access value as

SpringApplication.run(AppSiteController.class, args).getBean("value");

and pass in command line

-Dserver.port=...

Upvotes: 0

mukesh210
mukesh210

Reputation: 2892

For Spring Boot 2.x, you can override system properties like below:

mvn spring-boot:run -Dspring-boot.run.arguments=--server.port=8085

By default,Spring Boot converts command-line arguments to properties and adds them as environment variables.

You can access command line argument from application's main method as:

@SpringBootApplication
public class Application extends SpringBootServletInitializer {
    public static void main(String[] args) {
        for(String arg:args) {
            System.out.println(arg);
        }
        SpringApplication.run(Application.class, args);
    }
}

This will print the arguments we passed to our application from command-line.

Upvotes: 1

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