在AlarmManager中设置每隔一小时周期发送广播，设置后能在adb shell中看到。但一般在经过一个周期之后，再次adb shell中查看，就发现alarmmanager中已经没有装订好的广播了。难道是被os自行取消了？我的手机os是miui7 5.10.8开发版 android 5.1。
装订后，在adb shell看到的形式一般如下，

RTC #2: Alarm{3a928873 type 1 when 1446138667081 com.example.weathertrack} tag=*alarm*:com.example.weather.WAKEUP operation=PendingIntent{b5186f4: PendingIntentRecord{3d8cfe1d com.example.weathertrack broadcastIntent}} u0a233:com.example.weathertrack +1s109ms running, 0 wakeups: +1s109ms 0 wakes 2 alarms: *alarm*:com.example.weather.WAKEUP

设置alarmmanager的代码如下，

public static void sendBroadcast(Context context) { AlarmManager manager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); long setTime = 1000 * 3600; Intent intent = new Intent(context, WakeUpApp.class); intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES); intent.setAction("com.example.weather.WAKEUP"); PendingIntent pendingIntent = PendingIntent .getBroadcast(context, 1562, intent, PendingIntent.FLAG_UPDATE_CURRENT); manager.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 1000 * 60, setTime, pendingIntent); }

在AndroidManifest中receiver的定义如下，

ADD 1:
我在开发者选项中设置了不锁定屏幕，这样在充电中手机就不会休眠。从中午开始到现在，可以发现AlarmManager运行良好，并没有出现定时广播消失的情况…………看来只能明早起来再看，手机在休眠状态下，定时广播是不是会消失。另外，我已经严重怀疑这是miui的锅，在这过程中我大概找到了另一个让人莫名其妙的bug的出现原因。
ADD2
上午再次在adb shell中查看，定时广播果然没了……看来只要待机时间一长，定时广播就会被取消，实在让人费解。
ADD3
让人帮忙在别的手机上试下，定时更新数据正常，看来这是miui的坑了。
另外还有一个坑。在我app中，本来是想定时发送广播唤起后台服务，然后下载数据。我发现即使AlarmManager正常工作，唤醒后台服务之后，下载必然会报错，

10-30 13:46:37.929 26642-26673/com.example.weathertrack W/System.err: java.net.ConnectException: failed to connect to api.thinkpage.cn/115.29.232.24 (port 443) after 10000ms: isConnected failed: ECONNREFUSED (Connection refused) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at libcore.io.IoBridge.isConnected(IoBridge.java:238) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at libcore.io.IoBridge.connectErrno(IoBridge.java:171) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:122) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:456) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.net.Socket.connect(Socket.java:882) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.internal.Platform$Android.connectSocket(Platform.java:190) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Connection.connectSocket(Connection.java:196) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Connection.connect(Connection.java:172) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Connection.connectAndSetOwner(Connection.java:367) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:128) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:328) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:245) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Call.getResponse(Call.java:267) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Call$ApplicationInterceptorChain.proceed(Call.java:224) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Call.getResponseWithInterceptorChain(Call.java:195) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Call.access$100(Call.java:34) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.Call$AsyncCall.execute(Call.java:162) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at com.squareup.okhttp.internal.NamedRunnable.run(NamedRunnable.java:33) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at java.lang.Thread.run(Thread.java:818) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: Caused by: android.system.ErrnoException: isConnected failed: ECONNREFUSED (Connection refused) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: at libcore.io.IoBridge.isConnected(IoBridge.java:223) 10-30 13:46:37.939 26642-26673/com.example.weathertrack W/System.err: ... 21 more

看日志第一行，我查过之后发现这个错误一般是因为服务器端出错造成的。但是在我这个例子中肯定不是网站服务器的问题，每次只要我在打开app的情况下手动更新数据，就能正常下载数据。另外，今天下午别人的测试反馈也是软件定时更新数据正常。
我在adb shell中查看了logcat，发现只要开始网络连接，小米内置的网络助手就会监控，

10-30 13:46:37.929 I/XiaomiFirewall(10262): firewall pkgName:com.example.weathertrack, result:0

但是无法确认是不是小米网络助手的问题，因为即使正常连接，也会返回如上日志。