README.md

cli4j

A tiny library for turning CLIs into Java APIs.

cli4j allows you to quickly create a Java API for any command-line tool. It is itself a fluent API and excels at helping you create a fluent API for a command-line tool.

Example

Say you want to create an API for OpenStack's Nova service (since none of the SDKs you've found have all the features that are available from the command-line -- some of which you need). Start by creating a NovaCli class that extends the Command abstract class.

import net.evanstoner.cli4j.Command;

public class NovaCli extends Command {

  public NovaCli(String username, String password, String tenantName, String authUrl) {
    super("nova");
    longOption("os-username", username);
    longOption("os-password", password);
    longOption("os-tenant-name", tenantName);
    longOption("os-auth-url", authUrl);
  }
  
}

Now you can declare a Nova client like this:

NovaCli nova = new NovaCli("user", "passw0rd", "tenant", "http://openstack-server:5000");

To add the add-fixed-ip command, you need to create another Command subclass:

import net.evanstoner.cli4j.Command;

class AddFixedIpCommand extends Command {

    public AddFixedIpCommand(NovaCli nova) {
        super("add-fixed-ip", nova);
    }

    public AddFixedIpCommand server(String serverNameOrId) {
        positional(0, serverNameOrId);
        return this;
    }

    public AddFixedIpCommand networkId(String networkId) {
        positional(1, networkId);
        return this;
    }

}

Then create a method to get an instance of this command in NovaCli:

public AddFixedIpCommand addFixedIp() {
  return new AddFixedIpCommand(this);
}

And finally, use it:

Result r = nova.addFixedIp().server("my-server").networkId("some-uuid").exec();
if (!r.isSuccessful()) {
  System.out.println("ERROR: " + r.getErrorOutput());
}

You can see this example and more in the examples package.