Command Executor

In traditional Bukkit plugin development, we usually use the CommandExecutor interface of Bukkit to handle commands.

However, in some cases, we need to determine whether the sender of the command is a player, whether it has certain permissions, and determine the parameters, etc.

If a plugin has multiple commands, then these judgment logic will be repeated in the processing method of each command, such code is very redundant.

In addition, we may also need to handle command errors, output help information, etc.

UltiTools-API offers a more concise way to handle commands by encapsulating the native CommandExecutor interface.

Create a command executor

You only need to inherit the AbstractCommandExecutor class and override the handleHelp method. The @CmdTarget and @CmdExecutor annotations here represent the target type and executor information of the command.

import com.ultikits.ultitools.abstracts.AbstractCommendExecutor;
import com.ultikits.ultitools.annotations.command.CmdExecutor;
import com.ultikits.ultitools.annotations.command.CmdTarget;
import org.bukkit.command.CommandSender;

// Command limits executor
@CmdTarget(CmdTarget.CmdTargetType.BOTH)
@CmdExecutor(
        // Command permission (optional)
        permission = "ultikits.example.all",
        // Command description (optional)
        description = "测试指令",
        // Command alias
        alias = {"test", "ts"},
        // Whether to register manually (optional)
        manualRegister = false,
        // Whether to require OP permission (optional)
        requireOp = false
)
public class ExampleCommand extends AbstractCommendExecutor {

    @Override
    protected void handleHelp(CommandSender sender) {
        // Send help message to command sender
    }
}

You have completed an empty command executor that does nothing! The @CmdTarget and @CmdExecutor annotations here represent the sender type and executor information of the command. We will introduce these two annotations in detail in the next section.

Register command

The same as spigot development, with the executor, you need to register it. We can use the getCommandManager().register() method to register the command in the registerSelf method.

If your module has a large number of command executors and you don't want to register them manually, you can also use the automatic registration provided by UltiTools, for details, please refer to this article.

import com.ultikits.plugin.ultikitsapiexample.context.ContextConfig;
import com.ultikits.ultitools.abstracts.UltiToolsPlugin;
import com.ultikits.ultitools.annotations.ContextEntry;
import com.ultikits.ultitools.annotations.EnableAutoRegister;

import java.io.IOException;
import java.util.List;

public class UltiToolsConnector extends UltiToolsPlugin {

    public UltiToolsConnector(String name, String version, List<String> authors, List<String> depend, int loadPriority, String mainClass) {
        super(name, version, authors, depend, loadPriority, mainClass);
    }

    @Override
    public boolean registerSelf() throws IOException {
        // register command
        getCommandManager().register(this, ExampleCommand.class);
        return true;
    }

    @Override
    public void unregisterSelf() {

    }

    @Override
    public void reloadSelf() {
        super.reloadSelf();
    }
}

Mapping-based command executor

Quick start

Assuming that your plugin has a function to set the teleport point, you want the player to enter a command with the teleport point name, so as to set up a teleport point.

Then this command should look like this: /point add name

If you use the traditional method, you need to judge the legality of the parameter input, the sender and permissions, etc. If there are other functions, you also need to write a lot of switch ... case and if ... else statements, crazy nesting.

However, with UltiTools, you only need to write the main logic, and the rest will be handled by UltiTools.

First, you need to create an executor class that inherits AbstractCommandExecutor.

Then create a method named addPoint and add the parameters you want:

public void addPoint(@CmdSender Player player, String name) {
  ...
}

Yes, each of your functions uses a separate function without extra judgment.

If you want to get the Player object instead of the CommandSender object, then you get the Player, you don't need to judge and convert at all. You only need to add the @CmdSender annotation in front of the parameter you want to get the sender object.

Then, you only need to add the @CmdMapping annotation so that UltiTools can match your method according to the input command:

@CmdMapping(format = "add <name>")
public void addPoint(@CmdSender Player player, String name) {
  ...
}

Finally, use @CmdParam to bind command parameters:

@CmdMapping(format = "add <name>")
public void addPoint(@CmdSender Player player, @CmdParam("name") String name) {
  ...
}

Till now, you only need to register the command executor to complete all the work.

Tab completion

Need Tab suggestion for each command parameter, but don't want to write a lot of code?

It is a disaster to generate a completion list by judging the length of each command and the previous parameters.

Now you only need to write a method for each parameter to return a completion list! This method can be reused, and all the complicated parameter quantity judgments are left to UltiTools to complete.

What you need to do is just add the suggest attribute in the @CmdParam annotation and specify a method name.

@CmdMapping(format = "add <name>")
public void addPoint(@CmdSender Player player, @CmdParam(value = "name", suggest = "listName") String name) {
  ...
}

public List<String> listName(Player player, Command command, String[] args) {
  ...
}

UltiTools will first search for matching method names in the current class and try to call this method.

Your method can contain up to three parameters, corresponding to the types Player, Command and String[]. You can choose any amount or order of parameters, but the type can only be these three types, one parameter for each type.

Player represents the player who sent the command, Command represents the current command, and String[] represents the current parameters of the current command.

Your method needs to return a value of type List<String>, and UltiTools will return this value as a completion list to the player.

TIP

If you just want to return a simple prompt string, then you only need to write the string you want in the suggest field. The string here also supports internationalization.

@CmdMapping(format = "add <name>")
public void addPoint(@CmdSender Player player,
                     @CmdParam(value = "name", suggest = "[name]") String name) {
  ...
}

TIP

If you are not satisfied with the completion list generated by UltiTools, you can override the suggest method to generate the completion list yourself.

@Override
protected List<String> suggest(Player player, Command command, String[] strings) {
    ...
}

@CmdSuggest

If you want a completion method to be shared with other command classes, you can create a class and write methods which you want to reuse in other class.

Add the @CmdSuggest annotation to the class which need to use suggestion method, and specify the suggestion class.

@CmdSuggest({PointSuggest.class})
public class PointCommand extends AbstractCommandExecutor {

    @CmdMapping(format = "add <name>")
    public void addPoint(@CmdSender Player player, @CmdParam(value = "name", suggest = "listName") String name) {
        ...
    }
}

public class PointSuggest {
    public List<String> listName(Player player, Command command, String[] args) {
        ...
    }
}

Parameters

Command without Parameters

If a command does not require any parameters, simply leave the format value empty.

@CmdMapping(format="")

This type of command can have at most one occurrence.

Variable Parameters

For the last parameter in a method, you can use an array type by adding ... to the last parameter in the format. Here's an example:

@CmdMapping(format = "add <name...>")
public void addPoint(@CmdSender Player player, @CmdParam(value = "name...") String[] name) {
  ...
}

In this example, when a player enters /somecmd add aa bb cc, the name will be ['aa', 'bb', 'cc'].

Type Parsing

Before passing parameters to a method, UltiTools converts the command's variable parameters based on the types required by the method.

All parsers are stored in a map called parsers, and you can use getParser() to access it.

For some types, AbstractCommandExecutor provides default parsers (including base types and arrays):

• String (Java built-in)
• Float (Java built-in)
• Double (Java built-in)
• Integer (Java built-in)
• Short (Java built-in)
• Byte (Java built-in)
• Long (Java built-in)
• OfflinePlayer (Bukkit API)
• Player (Bukkit API)
• Material (Bukkit API)
• UUID (Java built-in)
• Boolean (Java built-in)

If you want to use a custom parser, you need to create a method that can be used with the Function interface.

Supported parser types are <String, ?>, meaning the method has exactly one parameter of type String and returns a value of any type.

public static SomeType toSomeType(String s) {
  //do something...
  return result;
}

Then, add the converter in the constructor:

public SomeCommand() {
  super();
  getParsers().put(Arrays.asList(SomeType.class, SomeType[].class), SomeType::toSomeType);
}

WARNING

Make sure to add the array type as well; otherwise, variable parameters won't be parsed.

Permission

Method permission

If you need to specify permissions for a method, you need to add the permission attribute in the @CmdMapping annotation.

@CmdMapping(..., permission = "point.set.add")

TIP

The permissions specified in @CmdExecutor will override any permission set in @CmdMapping.

OP Required

If you want all methods to be executed by OP only, you need to set the requireOp attribute in @CmdExecutor to true

@CmdExecutor(..., requireOp = true)

If you want a method to be executed by OP only, you need to set the requireOp attribute in @CmdMapping to true

@CmdMapping(..., requireOp = true)

Sender Limitation

If you want to specify the sender for all methods, you need to add the @CmdTarget annotation in front of your class.

If you want to specify the sender for a method, just add it in front of the method.

@CmdTarget(CmdTarget.CmdTargetType.BOTH)

TIP

If the sender is specified in both the class and the method, both must be met.

Asynchronous Execution

If a command needs to execute a task that takes a long time, you need to add @RunAsync in front of the corresponding

@CmdMapping(format = "list")
@RunAsync
public void listPoint(@CmdSender Player player) {
    //do query
}

This will create a new asynchronous thread to execute the method, avoiding blocking in the Bukkit main thread.

Since the Bukkit API does not allow asynchronous calls, if you need to call the Bukkit API, you need to create a synchronous task:

@CmdMapping(format = "list")
@RunAsync
public void listPoint(@CmdSender Player player) {
    //do query
    new BukkitRunnable() {
        @Override
        public void run() {
            //call bukkit api
        }
    }.runTask(PluginMain.getInstance());
}

Command cooldown

If you don't want a command to be executed in large quantities and consume server resources, then you can add @CmdCD in front of the corresponding method:

@CmdCD(60)

Parameter type is integer, in second.

If the command is executed before the cooldown ends, the message Frequent operations, please try again later will be sent.

This restriction only takes effect on players.

Execution lock

If you want a command to be executed only one by one, you can add @UsageLimit in front of the corresponding method:

@UsageLimit(ContainConsole = false, value = LimitType.SENDER)

ContainConsole is whether the restriction is applied to the console, and value is the restriction type.

Available types are:

• LimitType.SENDER limits that each sender can only have one command of this type executed at a time
• LimitType.ALL limits that only one command of this type can be executed in the whole server
• LimitType.NONE no limit

Under the LimitType.SENDER strategy, the player will receive a prompt: Please wait for last Command Processing!

Under the LimitType.ALL strategy, the player will receive a prompt: Please wait for last Command Processing which sent by other players!

Vanilla Bukkit Command Executor Wrapper

Player Command

If you want a command to be executed only in the game (executed by the player), you can inherit the AbstractPlayerCommandExecutor class and override the onPlayerCommand method.

public class SomeCommands extends AbstractPlayerCommandExecutor {
    @Override
    protected boolean onPlayerCommand(Command command, String[] strings, Player player) {
        // your code
        return true;
    }
}

Except for the Player type parameter, this method is the same as the CommandExecutor#onCommand method.

If you try to execute this command in the console, you will receive an error message: This command can only be performed in GAME!

If you want this command to use Tab completion, please see the next section.

Command Completion

From Minecraft 1.13, the Bukkit API provides a new TabCompleter interface for command completion.

UltiTools has encapsulated this interface to provide a more concise way of command completion.

You need to inherit the AbstractTabExecutor class and override the onTabComplete method.

@Override
protected List<String> onPlayerTabComplete(Command command, String[] strings, Player player) {
    // your code
    return null;
}

Except for the Player type parameter, this method is the same as the TabCompleter#onTabComplete method.

The rest of the usage is the same as the AbstractPlayerCommandExecutor class.

Console Command

If you want a command to be executed only in the console, you can inherit the AbstractConsoleCommandExecutor class and override the onConsoleCommand method.

public class SomeCommands extends AbstractConsoleCommandExecutor {
    @Override
    protected boolean onConsoleCommand(CommandSender commandSender, Command command, String[] strings) {
        // your code
        return true;
    }
}

This method is the same as the CommandExecutor#onCommand method.

If you try to execute this command in the game, you will receive an error message: This command can only be performed in CONSOLE!

Help Message

All three classes above provide a sendHelpMessage method for sending help messages to players or consoles.

sendHelpMessage(CommandSender sender) {
    // send help message
}

When sending the /somecommand help command, this method will be called.

Error Message

You may find that the onCommand method of the three classes above returns a boolean type value.

It is the same as the native CommandExecutor interface, this value is used to indicate whether the command was executed successfully.

When the command execution returns false, the command sender will be automatically prompted with an error message.