How to get command Line arguments in spring boot?

Question

@SpringBootApplication
public class CommandLinetoolApplication {

@Value("${person.name}")
private String name;

public static void main(String... argv) {
    SpringApplication.run(CommandLinetoolApplication.class, argv);
 }  
}

I am using eclipse so setting run configuration as
-Dspring-boot.run.arguments=--person.name=firstName

But when run my application,I am getting exception as "Could not resolve placeholder 'person.name' in value "${person.name}"

Answer 1

This code works just fine (Spring Boot 2.1.4):

@SpringBootApplication
public class DemoApplication implements ApplicationRunner
{

    @Value("${person.name}")
    private String name;

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

    @Override
    public void run( ApplicationArguments args ) throws Exception
    {
        System.out.println( "Name: " + name );
    }
}

Command line:

mvn spring-boot:run -Dspring-boot.run.arguments=--person.name=Test

The output:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.4.RELEASE)

2019-04-28 22:51:09.741  INFO 73751 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication on xxx-MacBook-Pro.local with PID 73751 (/Users/strelok/code/demo-sb/target/classes started by strelok in /Users/strelok/code/demo-sb)
2019-04-28 22:51:09.745  INFO 73751 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2019-04-28 22:51:10.943  INFO 73751 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 16.746 seconds (JVM running for 23.386)
Name: Test

Answer 2

You need to change your eclipse VM arguments as -Dperson.name=dhanraj

One more thing is there is no use to add private String name; in main class. Because main method is static method, so you need to create object to access name variable and ultimately new object gives you null value not the value you set dhanraj.

So Use this variable in Controller or Service part.

Answer 3

You need to add a configuration property person.name=firstName in your application.properties

OR

Implement interface ApplicationRunner and override its run method(Correct way to read command line argument)

Example:

@SpringBootApplication
public class Application implements ApplicationRunner {

    private static final Logger logger = LoggerFactory.getLogger(Application.class);

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

    @Override
    public void run(ApplicationArguments args) throws Exception {
        logger.info("Application started with command-line arguments: {}", Arrays.toString(args.getSourceArgs()));
        logger.info("NonOptionArgs: {}", args.getNonOptionArgs());
        logger.info("OptionNames: {}", args.getOptionNames());

        for (String name : args.getOptionNames()){
            logger.info("arg-" + name + "=" + args.getOptionValues(name));
        }

        boolean containsOption = args.containsOption("person.name");
        logger.info("Contains person.name: " + containsOption);
    }
}