Velocity API 1.1.0 Plugin messaging channel example

MessageListener.java

package com.velocityuser.exampleplugin;

import com.google.common.io.ByteArrayDataInput;
import com.google.common.io.ByteStreams;
import com.velocitypowered.api.event.Subscribe;
import com.velocitypowered.api.event.connection.PluginMessageEvent;
import com.velocitypowered.api.proxy.Player;
import com.velocitypowered.api.proxy.ServerConnection;
import com.velocitypowered.api.proxy.messages.ChannelIdentifier;

public class MessageListener {

	private final ChannelIdentifier identifier;

	public MessageListener(ChannelIdentifier identifier){
		this.identifier = identifier;
	}

	@Subscribe
	public void onPluginMessageEvent(PluginMessageEvent event){
		// Received plugin message, check channel identifier matches
		if(event.getIdentifier().equals(identifier)){
			// Since this message was meant for this listener set it to handled
			// We do this so the message doesn't get routed through.
			event.setResult(PluginMessageEvent.ForwardResult.handled());

			// Important! Check the origin of the plugin message
			// Depending on what the message does its critical that a player
			// is not able to spoof it
			if(event.getSource() instanceof Player){
				// Most of the time you want to defer the player
				// from being able to interact with this handler.
				// You could just return from here or if you're feeling
				// especially evil you could kick them

			}
			// Could also instead be
			if(event.getSource() instanceof ServerConnection){
				// Read the data written to the message
				ByteArrayDataInput in = ByteStreams.newDataInput(event.getData());
				// Example:
				String message = in.readUTF();

			}

		}

	}


}

VelocityPlugin.java

package com.velocityuser.exampleplugin;

import com.google.common.io.ByteArrayDataOutput;
import com.google.common.io.ByteStreams;
import com.google.inject.Inject;
import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
import com.velocitypowered.api.event.Subscribe;
import com.velocitypowered.api.plugin.Plugin;
import com.velocitypowered.api.proxy.Player;
import com.velocitypowered.api.proxy.ProxyServer;
import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
import org.slf4j.Logger;

@Plugin(
		id = "exampleplugin",
		name = "ExamplePlugin",
		version = "@version@",
		description = "Plugin channel example plugin",
		authors = {"VelocityContributor"}
)
public class VelocityPlugin {

	@Inject
	private Logger logger;

	@Inject
	private ProxyServer proxy;

	// The messaging channel you're going to use as namespaced:key
	private final ChannelIdentifier customChannel =
			MinecraftChannelIdentifier.from("customplugin:mychannel");

	@Subscribe
	public void onProxyInitialization(ProxyInitializeEvent event) {
		// Register the custom messaging channel
		proxy.getChannelRegistrar().register(customChannel);
		// Register an event handler to catch messages for it
		proxy.getEventManager().register(this, new MessageListener(customChannel));
	}

	public void sendExampleMessage(ChannelMessageSink receiver, String message){
		// Write whatever you want to send to a buffer
		ByteArrayDataOutput buf = ByteStreams.newDataOutput();
		buf.writeUTF(message);
		// Send it
		receiver.sendPluginMessage(customChannel, buf.toByteArray());
	}
}