Pull over the AnnotatedMessageHandler from Client

src/main/java/com/flowpowered/networking/util/AnnotatedMessageHandler.java

@@ -0,0 +1,99 @@
+/*
+ * This file is part of Flow Networking, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2013 Spout LLC <http://www.spout.org/>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.flowpowered.networking.util;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.flowpowered.networking.Message;
+
+/**
+ * A class for handling messages with annotated methods referred to as handles. The methods need to be annotated with {@link com.flowpowered.networking.util.AnnotatedMessageHandler.Handle} and should only
+ * have one parameter, the message, which needs to be a subclass of {@link com.flowpowered.networking.Message}. These should be instance methods inside any class. When creating the annotated message
+ * handler, an instance of the class containing the method is passed to the constructor. Handle methods will be called from this instance when handling messages. To handle a message, simply call
+ * {@link #handle(com.flowpowered.networking.Message)} with the said message as a parameter. The thread calling {@link #handle(com.flowpowered.networking.Message)} is the same that calls the handle
+ * method.
+ */
+public class AnnotatedMessageHandler {
+    private final Map<Class<?>, Method> handles = Collections.synchronizedMap(new HashMap<Class<?>, Method>());
+    private final Object handler;
+
+    /**
+     * Constructs a new annotated message handler using the passed object as the source of handle methods.
+     *
+     * @param handler The message handler
+     */
+    public AnnotatedMessageHandler(Object handler) {
+        this.handler = handler;
+        registerHandlers();
+    }
+
+    /**
+     * Handles the given message.
+     *
+     * @param message The message to handle
+     */
+    public void handle(Message message) {
+        final Method handle = handles.get(message.getClass());
+        if (handle == null) {
+            throw new IllegalArgumentException("No handle for message type [" + message.getClass().getName() + "]");
+        }
+        try {
+            handle.invoke(handler, message);
+        } catch (Exception ex) {
+            throw new RuntimeException("Failed to handle message [" + message + "]", ex);
+        }
+    }
+
+    private void registerHandlers() {
+        for (Method method : handler.getClass().getDeclaredMethods()) {
+            if (method.isAnnotationPresent(Handle.class)) {
+                final Class<?>[] parameterTypes = method.getParameterTypes();
+                if (parameterTypes.length != 1) {
+                    throw new IllegalStateException("Expected only 1 parameter for message handler method [" + method.getName() + "]");
+                }
+                final Class<?> messageType = parameterTypes[0];
+                if (!Message.class.isAssignableFrom(messageType)) {
+                    throw new IllegalStateException("Expected parameter to be a subclass of Message for handler method [" + method.getName() + "]");
+                }
+                method.setAccessible(true);
+                handles.put(messageType, method);
+            }
+        }
+    }
+
+    /**
+     * The annotation to mark message handle methods.
+     */
+    @Target (ElementType.METHOD)
+    @Retention (RetentionPolicy.RUNTIME)
+    public static @interface Handle {
+    }
+}