feat: JoinRequestPacket

src/main/java/com/lapisberry/net/packets/ClientPacket.java

@@ -0,0 +1,12 @@
+package com.lapisberry.net.packets;
+
+import java.io.Serial;
+import java.io.Serializable;
+
+/**
+ * The {@code ClientPacket} class is a packet sending from client to server.
+ */
+public class ClientPacket implements Serializable {
+    @Serial
+    private static final long serialVersionUID = -2286074370601221667L;
+}

src/main/java/com/lapisberry/net/packets/JoinRequestPacket.java

@@ -0,0 +1,24 @@
+package com.lapisberry.net.packets;
+
+import java.io.Serial;
+import java.io.Serializable;
+
+/**
+ * The {@code JoinRequestPacket} class is the first packet sending from client to server to join the server.
+ */
+public class JoinRequestPacket extends ClientPacket implements Serializable {
+    @Serial
+    private static final long serialVersionUID = -3120924882895484001L;
+    // Fields
+    private final String username;
+
+    // Constructors
+    public JoinRequestPacket(String username) {
+        this.username = username;
+    }
+
+    // Getters
+    public String getUsername() {
+        return username;
+    }
+}

src/main/java/com/lapisberry/net/packets/ServerPacket.java

@@ -0,0 +1,12 @@
+package com.lapisberry.net.packets;
+
+import java.io.Serial;
+import java.io.Serializable;
+
+/**
+ * The {@code ServerPacket} class is a packet sending from server to client.
+ */
+public class ServerPacket implements Serializable {
+    @Serial
+    private static final long serialVersionUID = 726935260428407157L;
+}