Android frameworks 开发总结之十一

1.查看android关机前的log    

有时候我们在没有连接电脑的情况下,会在测试的时候突然机器关机. 这个时候如果查看 log信息就看不到了。测试前可以执行下面的命令，之后再进行测试.

$ adb shell
$ nohup logcat > /sdcard/xxx.log

2.android日期时间同步

关于android请求日期时间同步的具体方法在frameworks/base/core/java/android/util/NtpTrustedTime.java文件中的forceSync方法中
 

3.SD card mount 和unmount以及notification

关于sdcard mount和unmount的代码: frameworks/base/services/core/java/com/android/server/StorageManagerService.java.

SD card在mount或之unmount成功之后发送的通知:

frameworks/base/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java

在arashi的测试过程中要求在多用户的情况下，sdcard不能被认到，解决办法是从两个部分处理。
A.在外置sdcard成功mount之后，检测如果是外置sdcard，则进行unmount的操作。

private void mount(VolumeInfo vol) {try {// TODO(b/135341433): Remove paranoid logging when FUSE is stableSlog.i(TAG, "Mounting volume " + vol);mVold.mount(vol.id, vol.mountFlags, vol.mountUserId, new IVoldMountCallback.Stub() {@Overridepublic boolean onVolumeChecking(FileDescriptor fd, String path,String internalPath) {vol.path = path;vol.internalPath = internalPath;ParcelFileDescriptor pfd = new ParcelFileDescriptor(fd);try {mStorageSessionController.onVolumeMount(pfd, vol);return true;} catch (ExternalStorageServiceException e) {Slog.e(TAG, "Failed to mount volume " + vol, e);int nextResetSeconds = FAILED_MOUNT_RESET_TIMEOUT_SECONDS;Slog.i(TAG, "Scheduling reset in " + nextResetSeconds + "s");mHandler.removeMessages(H_RESET);mHandler.sendMessageDelayed(mHandler.obtainMessage(H_RESET),TimeUnit.SECONDS.toMillis(nextResetSeconds));return false;} finally {try {pfd.close();} catch (Exception e) {Slog.e(TAG, "Failed to close FUSE device fd", e);}}}});Slog.i(TAG, "Mounted volume " + vol);if(!vol.path.contains("emulated")){UserManager userManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);mExternalVolumeId = vol.getId();if(userManager.getUserCount() > 1){ //检测当且用户个数是否是两个或以上unmount(vol);  //进行unmount操作mExternalVolumeId = null;}}} catch (Exception e) {Slog.wtf(TAG, e);}}

在settings → storage中如果unmount之后会显示enject, 这个时候需要在packages/apps/Settings/src/com/android/settings/deviceinfo/StorageSettings.java文件中隐藏外置sdcard的显示

private synchronized void refresh() {...mInternalCategory.addPreference(mInternalSummary);UserManager userManager = (UserManager)getPrefContext().getSystemService(Context.USER_SERVICE);....for (VolumeInfo vol : volumes) {if (vol.getType() == VolumeInfo.TYPE_PRIVATE) {....} else if (vol.getType() == VolumeInfo.TYPE_PUBLIC|| vol.getType() == VolumeInfo.TYPE_STUB) {if(userManager.getUserCount() <= 1) {mExternalCategory.addPreference(new StorageVolumePreference(context, vol, 0));}}}....// Show unsupported disks to give a chance to initfinal List<DiskInfo> disks = mStorageManager.getDisks();for (DiskInfo disk : disks) {if (disk.volumeCount == 0 && disk.size > 0) {....if(userManager.getUserCount() <= 1) {mExternalCategory.addPreference(pref);}}}...if (mExternalCategory.getPreferenceCount() > 0 && userManager.getUserCount() <= 1) {getPreferenceScreen().addPreference(mExternalCategory);}...}

B.在创建user或者Guest完成之后，如果外置sdcard已经mount, 则进行unmount操作，通过广播的方式通知StorageManagerService.java。
package/apps/src/com/android/settings/users/UserSettings.java
 

private Handler mHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case MESSAGE_UPDATE_LIST:updateUserList();break;case MESSAGE_USER_CREATED:sendUnmountBroadcast(); //user 创建完成发送广播onUserCreated(msg.arg1);break;}}};…@Overridepublic boolean onPreferenceClick(Preference pref) {if (pref == mMePreference) {…...} else if (pref == mAddGuest) {mAddGuest.setEnabled(false); // prevent multiple tap issueUserInfo guest = mUserManager.createGuest(getContext(), getString(com.android.settingslib.R.string.user_guest));sendUnmountBroadcast();//Guest 创建完成发送广播openUserDetails(guest, true);return true;}return false;}