How pass and parse json to spring boot standalone application?

Question

For example:

java -jar mySpringApplication --myJsonParameter="{\"myKey\":\"myValue\"}"

This should be resolved like that:

public class MyService {
    @Autowired
    //or @Value("myJsonParameter") ? 
    private MyInputDto myInputDto;
}

public class MyInputDto {
    private String myKey;
}

The idea is to pass named parameter from command line (and following spring externalization practics) but inject Typed value parsed from json, not string.

Answer 1

You can try using property spring.application.json and annotate your MyInputDto as @org.springframework.boot.context.properties.ConfigurationProperties .

Start your application like this:

java -Dspring.application.json='{"myKey":"myValue"}' -jar mySpringApplication.jar

Implementing your service:

@EnableConfigurationProperties(MyInputDto.class)
public class MyService {

    @Autowired
    private MyInputDto myInputDto;

    // use myInputDto.getMyKey();

}

@ConfigurationProperties
public class MyInputDto {
    private String myKey;

    public String getMyKey() { return this.myKey; }

    public void setMyKey(String myKey) { this.myKey = myKey; }
}

See Spring external configuration documentation for more information.

Answer 2

You can implement CommandLineRunner to your springboot main class and then prepare Bean like this:

@Bean
public MyInputDto prepareMyInputDto(){
    return new MyInputDto();
}

Then in your run method you can set values from command line argument.

@Override
public void run(String... args) throws Exception {
    MyInputDto bean = context.getBean(MyInputDto.class);
    bean.setMyKey(args[0]);
}