添加encode编码接口

src/main/java/club/joylink/xiannccda/ats/message/MessageData.java

@@ -1,6 +1,7 @@
 package club.joylink.xiannccda.ats.message;
 
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
 
 public abstract class MessageData {
 
@@ -42,4 +43,30 @@ public abstract class MessageData {
    * @throws Exception
    */
   public abstract void decode2(ByteBuf buf) throws Exception;
+
+  /**
+   * 消息总长度: 时间戳（Time）长度+ 版本号（Version）长度+消息ID（message _id）长度（2字节）+ 消息内容（content）长度。
+   *
+   * @return
+   */
+  public abstract int messageLength();
+
+  public ByteBuf encode() {
+    final int messageLength = this.messageLength();
+    ByteBuf buf = Unpooled.buffer(messageLength + 2);
+    buf.writeShort(messageLength);
+    buf.writeInt((int) this.time);
+    buf.writeShort(this.version);
+    buf.writeShort(this.msgId.val);
+    this.encode2(buf);
+    return buf;
+  }
+
+  /**
+   * 编码，通用部分已经处理，只需接着往后写即可
+   *
+   * @param buf
+   */
+  protected abstract void encode2(ByteBuf buf);
+
 }