Java Spigot Websocket

Question

I wonder how can I add a websocket server into my java spigot plugin. I tried this and got an error.

public class Main extends JavaPlugin {

    @Override
    public void onEnable() {
        
        System.out.println("STARTED YEY :D");
        InetAddress host;
        try {
            host = InetAddress.getLocalHost();
             System.out.println(host);
                System.out.println("Working Directory = " + System.getProperty("user.dir"));
                int port = 8887;

                WebSocketServer server = new websocket(new InetSocketAddress(host, port));
                server.run();
                
                System.out.println("websocket started");

                
                new MainCommand(this);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
       
    }

but I've got this error

Could not load 'plugins/plugin5.4.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: org/java_websocket/server/WebSocketServer
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:149) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:394) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:301) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_18_R2.CraftServer.loadPlugins(CraftServer.java:407) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at org.bukkit.craftbukkit.v1_18_R2.CraftServer.reload(CraftServer.java:915) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at org.bukkit.Bukkit.reload(Bukkit.java:801) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:27) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_18_R2.CraftServer.dispatchCommand(CraftServer.java:826) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.network.PlayerConnection.a(PlayerConnection.java:1957) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.network.PlayerConnection.a(PlayerConnection.java:1796) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.network.PlayerConnection.a(PlayerConnection.java:1777) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.network.protocol.game.PacketPlayInChat.a(PacketPlayInChat.java:46) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.network.protocol.game.PacketPlayInChat.a(PacketPlayInChat.java:1) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.network.protocol.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:31) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.TickTask.run(SourceFile:18) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.util.thread.IAsyncTaskHandler.d(SourceFile:157) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.util.thread.IAsyncTaskHandlerReentrant.d(SourceFile:23) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1190) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:1) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.util.thread.IAsyncTaskHandler.y(SourceFile:131) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.be(MinecraftServer.java:1169) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.y(MinecraftServer.java:1162) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.util.thread.IAsyncTaskHandler.c(SourceFile:140) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.x(MinecraftServer.java:1146) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:1051) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:304) ~[spigot-1.18.2-R0.1-SNAPSHOT.jar:3482-Spigot-42b6152-e87f2e3]
        at java.lang.Thread.run(Thread.java:833) [?:?]
Caused by: java.lang.NoClassDefFoundError: org/java_websocket/server/WebSocketServer
        at java.lang.Class.forName0(Native Method) ~[?:?]
        at java.lang.Class.forName(Class.java:467) ~[?:?]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:67) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:145) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        ... 27 more
Caused by: java.lang.ClassNotFoundException: org.java_websocket.server.WebSocketServer
        at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:147) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:99) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[?:?]
        at java.lang.Class.forName0(Native Method) ~[?:?]
        at java.lang.Class.forName(Class.java:467) ~[?:?]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:67) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:145) ~[spigot-api-1.18.2-R0.1-SNAPSHOT.jar:?]
        ... 27 more

Are you using maven or gradle ? – Elikill58 Apr 25 '22 at 06:55 — Elikill58, Apr 25 '22 at 06:55

score 0 · Answer 1 · answered Apr 26 '22 at 06:30

You seems to include a dependency in your project, but don't export it with the jar. So, your plugin don't find the class.

To include dependencies in jar, you should follow this question: Including dependencies in a jar with Maven, more specially add this in your pom.xml file :

<build>
   <plugins>
      <!-- any other plugins -->
      <plugin>
         <artifactId>maven-assembly-plugin</artifactId>
         <executions>
            <execution>
               <phase>package</phase>
               <goals>
                  <goal>single</goal>
               </goals>
            </execution>
         </executions>
         <configuration>
            <descriptorRefs>
               <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
         </configuration>
      </plugin>
   </plugins>
</build>

Don't forget to use good jar (the one with -with-dependencies in the name)

how to add the good jar (the one with -with-dependencies in the name) — Tigron, May 02 '22 at 01:29
After running build, you should copy the jar with `-with-dependencies` in the name to the plugins folder into your server — Elikill58, May 02 '22 at 10:45

Java Spigot Websocket

1 Answers1