This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Shell 3.2.4!

Command Catalog

The CommandCatalog interface defines how command registrations exist in a shell application. It is possible to dynamically register and de-register commands, which gives flexibility for use cases where possible commands come and go, depending on a shell’s state. Consider the following example:

CommandRegistration registration = CommandRegistration.builder().build();
catalog.register(registration);

Command Resolver

You can implement the CommandResolver interface and define a bean to dynamically resolve mappings from a command’s name to its CommandRegistration instances. Consider the following example:

static class CustomCommandResolver implements CommandResolver {
	List<CommandRegistration> registrations = new ArrayList<>();

	CustomCommandResolver() {
		CommandRegistration resolved = CommandRegistration.builder()
			.command("resolve command")
			.build();
		registrations.add(resolved);
	}

	@Override
	public List<CommandRegistration> resolve() {
		return registrations;
	}
}

A current limitation of a CommandResolver is that it is used every time commands are resolved. Thus, we advise not using it if a command resolution call takes a long time, as it would make the shell feel sluggish.

Command Catalog Customizer

You can use the CommandCatalogCustomizer interface to customize a CommandCatalog. Its main use is to modify a catalog. Also, within spring-shell auto-configuration, this interface is used to register existing CommandRegistration beans into a catalog. Consider the following example:

static class CustomCommandCatalogCustomizer implements CommandCatalogCustomizer {

	@Override
	public void customize(CommandCatalog commandCatalog) {
		CommandRegistration registration = CommandRegistration.builder()
			.command("resolve command")
			.build();
		commandCatalog.register(registration);
	}
}

You can create a CommandCatalogCustomizer as a bean, and Spring Shell handles the rest.