Create a hashmap and manage different types of messages.

src/common/MessageManager.java

@@ -0,0 +1,41 @@
+package common;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.google.protobuf.GeneratedMessage;
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.MessageLite;
+
+/**
+ * 
+ * @author Yanran Lu
+ * 
+ */
+public class MessageManager {     //create messageMap to manage all messages
+	private static Map<Integer, MessageLite> messageMap = new HashMap<Integer, MessageLite>();
+
+	public static void addMessageCla(int id,    //add message to map
+			Class<? extends GeneratedMessage> msgCla)
+			throws NoSuchMethodException, SecurityException,
+			IllegalAccessException, IllegalArgumentException,
+			InvocationTargetException {
+		if (msgCla == null)
+			return;
+		Method method = msgCla.getMethod("getDefaultInstance");
+		MessageLite lite = (MessageLite) method.invoke(null, null);
+		messageMap.put(id, lite);
+	}
+
+	public static MessageLite getMessage(int id, byte[] body)   //get message from map
+			throws InvalidProtocolBufferException {
+		MessageLite list = messageMap.get(id);
+		if (list == null) {
+			System.err.printf("msg %d no register", id);
+			return null;
+		}
+		return list.newBuilderForType().mergeFrom(body).build();
+	}
+}