android 细节之 AndroidRuntimeException：This message is already in use

今天在做项目处理消息队列的时候。遇到了这样一个问题。一个异常。AndroidRuntimeException：This message is already in use。

我当时的详细业务需求情境为。想要跟硬件联动的时候。保持在一定时间内仅仅有一个操作。假设不idle。就又一次发送消息，而且此消息应该delay一段时间，就是TIMEDELAY。

详细出现错误的代码例如以下：

private class ChargecaseServiceHandler extends Handler {

		public ChargecaseServiceHandler(Looper looper) {
			super(looper);
		}

		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			Command command = new Command();
			command.command = msg.what;

			if (msg.obj != null) {
				command.data = (Bundle) msg.obj;
			}
			if (sIsLoopBleServiceReady) {
				if (isIdle) {
					switch (msg.what) {

					case MESSAGE_KILL:
						stopSelf();

						break;
					case MESSAGE_START_BLE_SCAN:
						startBLEScan();
						break;
					case MESSAGE_CONNECT:
						connect(command.data);
						break;
					case MESSAGE_DISCONNECT:
						attemptDisconnect();
						break;
					case MESSAGE_RELEASE_DEVICE_ID:
						clearData();
						break;
					case MESSAGE_INITIALIZE:
						initialize();
						break;
					case MESSAGE_RESET_BLE:
						resetBleController();
						break;
					case MESSAGE_STARTUP:
						startup();
						break;
					case MESSAGE_REGISTER:
						register(command.data);
						break;
					case MESSAGE_UNREGISTER:
						unregister(command.data);
						break;
					case MESSAGE_RECONNECT:
						reconnect();
						break;
					case MESSAGE_ADDCARD:
						addCard(command.data);
						break;
					case MESSAGE_GETCARDLIST:
						getCardList(command.data);
						// removeMessages(MESSAGE_GETCARDLIST);
						break;
					case MESSAGE_GETCARDDETAIL:
						getCardDetail(command.data);
						break;
					case MESSAGE_REMOVECARD:
						removeCard(command.data);
						break;
					case MESSAGE_CHECK_BATTERY:
						checkBattery();
						break;
					case MESSAGE_SET_DEFAULT_CARD:
						setDefaultCard(command.data);
						break;
					case MESSAGE_ZAP_CARD:
						zapCard(command.data);
						break;
					case MESSAGE_SET_LOCK_TIME:
						setLockTimer(command.data);
					}
				} else {
					sServiceHandler.sendMessageDelayed(msg, TIMEDELAY);
				}
			} else {
				Toast.makeText(getApplicationContext(),
						"Starting ble for you.", Toast.LENGTH_SHORT).show();
			}
		}
	}

然后上网搜了一下。发现实际上说明发送的消息正在消息队列中。表示如今正在被使用。

參考大神的博客后。（大神博客请移步http://blog.csdn.net/aa4790139/article/details/6579009）

发现解决方法：解决的方法又一次创建一个新的消息。发送过去就ok啦！问题解决。

于是我就准备new 一个 message或是obtain 一个message。而不是直接send这个message来进行delay。但是依旧出错，二次出错的代码例如以下：

private class ChargecaseServiceHandler extends Handler {

		public ChargecaseServiceHandler(Looper looper) {
			super(looper);
		}

		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			Command command = new Command();
			command.command = msg.what;

			if (msg.obj != null) {
				command.data = (Bundle) msg.obj;
			}
			if (sIsLoopBleServiceReady) {
				if (isIdle) {
					switch (msg.what) {

					case MESSAGE_KILL:
						stopSelf();

						break;
					case MESSAGE_START_BLE_SCAN:
						startBLEScan();
						break;
					case MESSAGE_CONNECT:
						connect(command.data);
						break;
					case MESSAGE_DISCONNECT:
						attemptDisconnect();
						break;
					case MESSAGE_RELEASE_DEVICE_ID:
						clearData();
						break;
					case MESSAGE_INITIALIZE:
						initialize();
						break;
					case MESSAGE_RESET_BLE:
						resetBleController();
						break;
					case MESSAGE_STARTUP:
						startup();
						break;
					case MESSAGE_REGISTER:
						register(command.data);
						break;
					case MESSAGE_UNREGISTER:
						unregister(command.data);
						break;
					case MESSAGE_RECONNECT:
						reconnect();
						break;
					case MESSAGE_ADDCARD:
						addCard(command.data);
						break;
					case MESSAGE_GETCARDLIST:
						getCardList(command.data);
						// removeMessages(MESSAGE_GETCARDLIST);
						break;
					case MESSAGE_GETCARDDETAIL:
						getCardDetail(command.data);
						break;
					case MESSAGE_REMOVECARD:
						removeCard(command.data);
						break;
					case MESSAGE_CHECK_BATTERY:
						checkBattery();
						break;
					case MESSAGE_SET_DEFAULT_CARD:
						setDefaultCard(command.data);
						break;
					case MESSAGE_ZAP_CARD:
						zapCard(command.data);
						break;
					case MESSAGE_SET_LOCK_TIME:
						setLockTimer(command.data);
					}
				} else {
					Message newMsg = sServiceHandler.obtainMessage();
					newMsg = msg。
					removeMessages(msg.what);
					LogHelper.i(LogHelper.CHARGECASE_TAG, newMsg.what + "");
					sServiceHandler.sendMessageDelayed(newMsg, TIMEDELAY);
				}
			} else {
				Toast.makeText(getApplicationContext(),
						"Starting ble for you.", Toast.LENGTH_SHORT).show();
			}
		}
	}

于是我就产生了思考，这样我得newMsg究竟是不是一个新的message呢？

肯定不是的，不然就没异常了。于是改变写法，让newMsg的what和obj等于原来msg的what和obj，这样做来保持通过handler传递的动作的一致性。和newMsg的崭新性。

果然，不再报异常了。

解决方法例如以下：

private class ChargecaseServiceHandler extends Handler {

		public ChargecaseServiceHandler(Looper looper) {
			super(looper);
		}

		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			Command command = new Command();
			command.command = msg.what;

			if (msg.obj != null) {
				command.data = (Bundle) msg.obj;
			}
			if (sIsLoopBleServiceReady) {
				if (isIdle) {
					switch (msg.what) {

					case MESSAGE_KILL:
						stopSelf();

						break;
					case MESSAGE_START_BLE_SCAN:
						startBLEScan();
						break;
					case MESSAGE_CONNECT:
						connect(command.data);
						break;
					case MESSAGE_DISCONNECT:
						attemptDisconnect();
						break;
					case MESSAGE_RELEASE_DEVICE_ID:
						clearData();
						break;
					case MESSAGE_INITIALIZE:
						initialize();
						break;
					case MESSAGE_RESET_BLE:
						resetBleController();
						break;
					case MESSAGE_STARTUP:
						startup();
						break;
					case MESSAGE_REGISTER:
						register(command.data);
						break;
					case MESSAGE_UNREGISTER:
						unregister(command.data);
						break;
					case MESSAGE_RECONNECT:
						reconnect();
						break;
					case MESSAGE_ADDCARD:
						addCard(command.data);
						break;
					case MESSAGE_GETCARDLIST:
						getCardList(command.data);
						// removeMessages(MESSAGE_GETCARDLIST);
						break;
					case MESSAGE_GETCARDDETAIL:
						getCardDetail(command.data);
						break;
					case MESSAGE_REMOVECARD:
						removeCard(command.data);
						break;
					case MESSAGE_CHECK_BATTERY:
						checkBattery();
						break;
					case MESSAGE_SET_DEFAULT_CARD:
						setDefaultCard(command.data);
						break;
					case MESSAGE_ZAP_CARD:
						zapCard(command.data);
						break;
					case MESSAGE_SET_LOCK_TIME:
						setLockTimer(command.data);
					}
				} else {
					Message newMsg = sServiceHandler.obtainMessage();
					newMsg.what = msg.what;
					newMsg.obj = msg.obj;
					removeMessages(msg.what);
					LogHelper.i(LogHelper.CHARGECASE_TAG, newMsg.what + "");
					sServiceHandler.sendMessageDelayed(newMsg, TIMEDELAY);
				}
			} else {
				Toast.makeText(getApplicationContext(),
						"Starting ble for you.", Toast.LENGTH_SHORT).show();
			}
		}
	}

switch的消息非常多。是业务须要，出现的异常也非常经典。特记录之。

PS：网上非常多解决方法是把new Message()换成obtainMessage()，有的说是把obtainMessage()换成new Message(). 个人亲測无法解决，或是无法解决我的问题。

PS2: 出现故障和解决这个问题的地方就是在倒数第二个else内。把其它的大段相关代码贴上来的目的是方便自己明确出错情境。请看官勿怪。

可是我的这样的方法是肯定能够解决类似问题。