- 涉及到的几个类
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SystemServer 负责启动初始化 LocationManagerService添加到系统服务中
LocationManagerService 借助AIDL提供给应用层调用各个定位逻辑的管理者，管理着各个的privoder
LocationManager 暴露给app层调用AIDL接调用LocationManagerService
GnssLocationProvider 主要的GPS定位逻辑，调用HAL层GPS模块进行定位和一些gps.config配置文件初始化属性的加载
查看当前运行的模式可以执行：
adb shell settings get secure location_providers_allowed 查看当前运行模式，模式可以为GPS 定位模式 ， network,gps 混合高精度定位 ，代码位置为 LocationSettings.java中，配置文件位置在frameworks/base/packages/SettingsProvider/res/values/defaults.xml def_location_providers_allowed 字段修改为 network,gps就是混合定位，只填写GPS就是GPS定位。
时序图.jpg
- 流程分析：
- 在app中定位一般是
getSystemService(Context.LOCATION_SERVICE) as LocationManager，然后调用 requestLocationUpdates进行位置的监听
getSystemService 最终调用的是ContextImpl在到 SystemServiceRegistry 中创建 LocationManager，在LocationManager中创建了LocationManagerService的AIDL对象
private void requestLocationUpdates(LocationRequest request, LocationListener listener,
Looper looper, PendingIntent intent) {
String packageName = mContext.getPackageName();
// wrap the listener class
ListenerTransport transport = wrapListener(listener, looper);
try {
mService.requestLocationUpdates(request, transport, intent, packageName);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
这里可以看到最终调用的是 mService 的 requestLocationUpdates方法而 mService 就是我们的LocationManagerService 的AIDL对象
-
LocationManagerService是什么时候初始化的？在`SystemServer` 初始化的时候初始化的我们可以在`startOtherServices` 方法中看到
traceBeginAndSlog("StartLocationManagerService");
try {
location = new LocationManagerService(context);
ServiceManager.addService(Context.LOCATION_SERVICE, location);
} catch (Throwable e) {
reportWtf("starting Location Manager", e);
}
traceEnd();
到此LocationManagerService创建完毕，接着我们看 LocationManagerService 中 requestLocationUpdates方法这里又调用到requestLocationUpdatesLocked方法
private void requestLocationUpdatesLocked(LocationRequest request, Receiver receiver,
int pid, int uid, String packageName) {
// Figure out the provider. Either its explicitly request (legacy use cases), or
// use the fused provider
if (request == null) request = DEFAULT_LOCATION_REQUEST;
这里获取具体的provder例如GPS ，net 这些，然后根据这个调用具体的provder对象
String name = request.getProvider();
if (name == null) {
throw new IllegalArgumentException("provider name must not be null");
}
判断是否有创建对应的provider,所有的provider都实现LocationProviderInterface接口
LocationProviderInterface provider = mProvidersByName.get(name);
if (provider == null) {
throw new IllegalArgumentException("provider doesn't exist: " + name);
}
UpdateRecord record = new UpdateRecord(name, request, receiver);
if (D) {
Log.d(TAG, "request " + Integer.toHexString(System.identityHashCode(receiver))
+ " " + name + " " + request + " from " + packageName + "(" + uid + " "
+ (record.mIsForegroundUid ? "foreground" : "background")
+ (isThrottlingExemptLocked(receiver.mIdentity)
? " [whitelisted]" : "") + ")");
}
UpdateRecord oldRecord = receiver.mUpdateRecords.put(name, record);
if (oldRecord != null) {
oldRecord.disposeLocked(false);
}
boolean isProviderEnabled = isAllowedByUserSettingsLocked(name, uid, mCurrentUserId);
if (isProviderEnabled) {
applyRequirementsLocked(name);
} else {
// Notify the listener that updates are currently disabled
receiver.callProviderEnabledLocked(name, false);
}
// Update the monitoring here just in case multiple location requests were added to the
// same receiver (this request may be high power and the initial might not have been).
receiver.updateMonitoring(true);
}
然后会进入到applyRequirementsLocked 方法
private void applyRequirementsLocked(String provider) {
#再次判断当前provder是否存在，如gps
LocationProviderInterface p = mProvidersByName.get(provider);
if (p == null) return;
ArrayList records = mRecordsByProvider.get(provider);
WorkSource worksource = new WorkSource();
ProviderRequest providerRequest = new ProviderRequest();
ContentResolver resolver = mContext.getContentResolver();
#默认后台的刷新时间是30分钟
long backgroundThrottleInterval = Settings.Global.getLong(
resolver,
Settings.Global.LOCATION_BACKGROUND_THROTTLE_INTERVAL_MS,
DEFAULT_BACKGROUND_THROTTLE_INTERVAL_MS);
// initialize the low power mode to true and set to false if any of the records requires
providerRequest.lowPowerMode = true;
if (records != null) {
for (UpdateRecord record : records) {
if (isCurrentProfile(UserHandle.getUserId(record.mReceiver.mIdentity.mUid))) {
if (checkLocationAccess(
record.mReceiver.mIdentity.mPid,
record.mReceiver.mIdentity.mUid,
record.mReceiver.mIdentity.mPackageName,
record.mReceiver.mAllowedResolutionLevel)) {
LocationRequest locationRequest = record.mRealRequest;
long interval = locationRequest.getInterval();
#系统和白名单的应用那么不会受到后台刷新时间的限制
if (!isThrottlingExemptLocked(record.mReceiver.mIdentity)) {
if (!record.mIsForegroundUid) {
interval = Math.max(interval, backgroundThrottleInterval);
}
if (interval != locationRequest.getInterval()) {
locationRequest = new LocationRequest(locationRequest);
locationRequest.setInterval(interval);
}
}
record.mRequest = locationRequest;
providerRequest.locationRequests.add(locationRequest);
if (!locationRequest.isLowPowerMode()) {
providerRequest.lowPowerMode = false;
}
if (interval < providerRequest.interval) {
providerRequest.reportLocation = true;
providerRequest.interval = interval;
}
}
}
}
if (providerRequest.reportLocation) {
// calculate who to blame for power
// This is somewhat arbitrary. We pick a threshold interval
// that is slightly higher that the minimum interval, and
// spread the blame across all applications with a request
// under that threshold.
long thresholdInterval = (providerRequest.interval + 1000) * 3 / 2;
for (UpdateRecord record : records) {
if (isCurrentProfile(UserHandle.getUserId(record.mReceiver.mIdentity.mUid))) {
LocationRequest locationRequest = record.mRequest;
// Don't assign battery blame for update records whose
// client has no permission to receive location data.
if (!providerRequest.locationRequests.contains(locationRequest)) {
continue;
}
if (locationRequest.getInterval() <= thresholdInterval) {
if (record.mReceiver.mWorkSource != null
&& isValidWorkSource(record.mReceiver.mWorkSource)) {
worksource.add(record.mReceiver.mWorkSource);
} else {
// Assign blame to caller if there's no WorkSource associated with
// the request or if it's invalid.
worksource.add(
record.mReceiver.mIdentity.mUid,
record.mReceiver.mIdentity.mPackageName);
}
}
}
}
}
}
if (D) Log.d(TAG, "provider request: " + provider + " " + providerRequest);
#开始调用具体的priover开启定位，这里如果是GPS就会走GnssLocationProvider的setRequest方法
p.setRequest(providerRequest, worksource);
}
这里的扩展点，所有的priover都是实现LocationProviderInterface接口，这里你需要实现自己的逻辑就可以添加自己的provider实现此接口，在在loadProvidersLocked方法注册你自己的provder就可以使用的
- 接下来进入到GPS的具体定位类
GnssLocationProvider,最终调用的是updateRequirements方法
private void updateRequirements() {
if (mProviderRequest == null || mWorkSource == null) {
return;
}
boolean singleShot = false;
// see if the request is for a single update
if (mProviderRequest.locationRequests != null
&& mProviderRequest.locationRequests.size() > 0) {
// if any request has zero or more than one updates
// requested, then this is not single-shot mode
singleShot = true;
for (LocationRequest lr : mProviderRequest.locationRequests) {
if (lr.getNumUpdates() != 1) {
singleShot = false;
}
}
}
if (DEBUG) Log.d(TAG, "setRequest " + mProviderRequest);
if (mProviderRequest.reportLocation && !mDisableGps && isEnabled()) {
// update client uids
updateClientUids(mWorkSource);
mFixInterval = (int) mProviderRequest.interval;
mLowPowerMode = (boolean) mProviderRequest.lowPowerMode;
// check for overflow
if (mFixInterval != mProviderRequest.interval) {
Log.w(TAG, "interval overflow: " + mProviderRequest.interval);
mFixInterval = Integer.MAX_VALUE;
}
// 初始化一些GPS设置
if (mStarted && hasCapability(GPS_CAPABILITY_SCHEDULING)) {
// change period and/or lowPowerMode
if (!native_set_position_mode(mPositionMode, GPS_POSITION_RECURRENCE_PERIODIC,
mFixInterval, 0, 0, mLowPowerMode)) {
Log.e(TAG, "set_position_mode failed in updateRequirements");
}
} else if (!mStarted) {
/#开始调用HAL层开启定位请求
startNavigating(singleShot);
} else {
// GNSS Engine is already ON, but no GPS_CAPABILITY_SCHEDULING
mAlarmManager.cancel(mTimeoutIntent);
if (mFixInterval >= NO_FIX_TIMEOUT) {
// set timer to give up if we do not receive a fix within NO_FIX_TIMEOUT
// and our fix interval is not short
mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
SystemClock.elapsedRealtime() + NO_FIX_TIMEOUT, mTimeoutIntent); }
}
} else {
updateClientUids(new WorkSource());
stopNavigating();
mAlarmManager.cancel(mWakeupIntent);
mAlarmManager.cancel(mTimeoutIntent);
}
}
当这里执行到 startNavigating 方法中就开始调用 native_start 执行HAL层的GPS模块定位逻辑，以上就是正向请求逻辑
- 现在定位信息返回逻辑
当GPS模块更新位置时，GPS JNI层将调用GnssLocationProvider的handleReportLocation函数，其代码如下所示。
private void handleReportLocation(boolean hasLatLong, Location location) {
if (VERBOSE) Log.v(TAG, "reportLocation " + location.toString());
#是否有速度
if (location.hasSpeed()) {
mItarSpeedLimitExceeded = location.getSpeed() > ITAR_SPEED_LIMIT_METERS_PER_SECOND;
}
if (mItarSpeedLimitExceeded) {
Log.i(TAG, "Hal reported a speed in excess of ITAR limit." +
" GPS/GNSS Navigation output blocked.");
if (mStarted) {
mGnssMetrics.logReceivedLocationStatus(false);
}
return; // No output of location allowed
}
if (VERBOSE) Log.v(TAG, "reportLocation " + location.toString());
// It would be nice to push the elapsed real-time timestamp
// further down the stack, but this is still useful
location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());
location.setExtras(mLocationExtras.getBundle());
try {
#开始调用LocationManagerServise的reportLocation方法回调位置
mILocationManager.reportLocation(location, false);
} catch (RemoteException e) {
Log.e(TAG, "RemoteException calling reportLocation");
}
if (mStarted) {
mGnssMetrics.logReceivedLocationStatus(hasLatLong);
if (hasLatLong) {
if (location.hasAccuracy()) {
mGnssMetrics.logPositionAccuracyMeters(location.getAccuracy());
}
if (mTimeToFirstFix > 0) {
int timeBetweenFixes = (int) (SystemClock.elapsedRealtime() - mLastFixTime);
mGnssMetrics.logMissedReports(mFixInterval, timeBetweenFixes);
}
}
}
mLastFixTime = SystemClock.elapsedRealtime();
// report time to first fix
if (mTimeToFirstFix == 0 && hasLatLong) {
mTimeToFirstFix = (int) (mLastFixTime - mFixRequestTime);
if (DEBUG) Log.d(TAG, "TTFF: " + mTimeToFirstFix);
if (mStarted) {
mGnssMetrics.logTimeToFirstFixMilliSecs(mTimeToFirstFix);
}
// notify status listeners
mListenerHelper.onFirstFix(mTimeToFirstFix);
}
if (mSingleShot) {
stopNavigating();
}
if (mStarted && mStatus != LocationProvider.AVAILABLE) {
// For devices that use framework scheduling, a timer may be set to ensure we don't
// spend too much power searching for a location, when the requested update rate is slow.
// As we just recievied a location, we'll cancel that timer.
if (!hasCapability(GPS_CAPABILITY_SCHEDULING) && mFixInterval < NO_FIX_TIMEOUT) {
mAlarmManager.cancel(mTimeoutIntent);
}
// send an intent to notify that the GPS is receiving fixes.
Intent intent = new Intent(LocationManager.GPS_FIX_CHANGE_ACTION);
intent.putExtra(LocationManager.EXTRA_GPS_ENABLED, true);
mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
updateStatus(LocationProvider.AVAILABLE);
}
if (!hasCapability(GPS_CAPABILITY_SCHEDULING) && mStarted &&
mFixInterval > GPS_POLLING_THRESHOLD_INTERVAL) {
if (DEBUG) Log.d(TAG, "got fix, hibernating");
hibernate();
}
}
通过上面又可以看到回调到 LocationManagerServise的reportLocation方法，最终会调用到handleLocationChangedLocked方法
private void handleLocationChangedLocked(Location location, boolean passive) {
if (D) Log.d(TAG, "incoming location: " + location);
long now = SystemClock.elapsedRealtime();
String provider = (passive ? LocationManager.PASSIVE_PROVIDER : location.getProvider());
// Skip if the provider is unknown.
LocationProviderInterface p = mProvidersByName.get(provider);
if (p == null) return;
#更新上一次最后的位置信息
updateLastLocationLocked(location, provider);
// mLastLocation should have been updated from the updateLastLocationLocked call above.
Location lastLocation = mLastLocation.get(provider);
if (lastLocation == null) {
Log.e(TAG, "handleLocationChangedLocked() updateLastLocation failed");
return;
}
// Update last known coarse interval location if enough time has passed.
Location lastLocationCoarseInterval = mLastLocationCoarseInterval.get(provider);
if (lastLocationCoarseInterval == null) {
lastLocationCoarseInterval = new Location(location);
mLastLocationCoarseInterval.put(provider, lastLocationCoarseInterval);
}
long timeDiffNanos = location.getElapsedRealtimeNanos()
- lastLocationCoarseInterval.getElapsedRealtimeNanos();
if (timeDiffNanos > LocationFudger.FASTEST_INTERVAL_MS * NANOS_PER_MILLI) {
lastLocationCoarseInterval.set(location);
}
// Don't ever return a coarse location that is more recent than the allowed update
// interval (i.e. don't allow an app to keep registering and unregistering for
// location updates to overcome the minimum interval).
Location noGPSLocation =
lastLocationCoarseInterval.getExtraLocation(Location.EXTRA_NO_GPS_LOCATION);
// Skip if there are no UpdateRecords for this provider.
ArrayList records = mRecordsByProvider.get(provider);
if (records == null || records.size() == 0) return;
// Fetch coarse location
Location coarseLocation = null;
if (noGPSLocation != null) {
coarseLocation = mLocationFudger.getOrCreate(noGPSLocation);
}
// Fetch latest status update time
long newStatusUpdateTime = p.getStatusUpdateTime();
// Get latest status
Bundle extras = new Bundle();
int status = p.getStatus(extras);
ArrayList deadReceivers = null;
ArrayList deadUpdateRecords = null;
// Broadcast location or status to all listeners
for (UpdateRecord r : records) {
Receiver receiver = r.mReceiver;
boolean receiverDead = false;
int receiverUserId = UserHandle.getUserId(receiver.mIdentity.mUid);
if (!isCurrentProfile(receiverUserId)
&& !isUidALocationProvider(receiver.mIdentity.mUid)) {
if (D) {
Log.d(TAG, "skipping loc update for background user " + receiverUserId +
" (current user: " + mCurrentUserId + ", app: " +
receiver.mIdentity.mPackageName + ")");
}
continue;
}
#黑名单app禁止使用定位
if (mBlacklist.isBlacklisted(receiver.mIdentity.mPackageName)) {
if (D) {
Log.d(TAG, "skipping loc update for blacklisted app: " +
receiver.mIdentity.mPackageName);
}
continue;
}
if (!reportLocationAccessNoThrow(
receiver.mIdentity.mPid,
receiver.mIdentity.mUid,
receiver.mIdentity.mPackageName,
receiver.mAllowedResolutionLevel)) {
if (D) {
Log.d(TAG, "skipping loc update for no op app: " +
receiver.mIdentity.mPackageName);
}
continue;
}
Location notifyLocation;
if (receiver.mAllowedResolutionLevel < RESOLUTION_LEVEL_FINE) {
notifyLocation = coarseLocation; // use coarse location
} else {
notifyLocation = lastLocation; // use fine location
}
if (notifyLocation != null) {
Location lastLoc = r.mLastFixBroadcast;
if ((lastLoc == null) || shouldBroadcastSafe(notifyLocation, lastLoc, r, now)) {
if (lastLoc == null) {
lastLoc = new Location(notifyLocation);
r.mLastFixBroadcast = lastLoc;
} else {
lastLoc.set(notifyLocation);
}
//DESAYSV AOSP IOV
if (D) { Log.i(TAG, "will call onLocationChanged on " + receiver); }
//DESAYSV AOSP IOV
#这里回掉了app层的位置信息回调，因为Listeners是封装在receiver里面的
if (!receiver.callLocationChangedLocked(notifyLocation)) {
Slog.w(TAG, "RemoteException calling onLocationChanged on " + receiver);
receiverDead = true;
}
r.mRealRequest.decrementNumUpdates();
}
}
long prevStatusUpdateTime = r.mLastStatusBroadcast;
if ((newStatusUpdateTime > prevStatusUpdateTime) &&
(prevStatusUpdateTime != 0 || status != LocationProvider.AVAILABLE)) {
r.mLastStatusBroadcast = newStatusUpdateTime;
if (!receiver.callStatusChangedLocked(provider, status, extras)) {
receiverDead = true;
Slog.w(TAG, "RemoteException calling onStatusChanged on " + receiver);
}
}
// track expired records
if (r.mRealRequest.getNumUpdates() <= 0 || r.mRealRequest.getExpireAt() < now) {
if (deadUpdateRecords == null) {
deadUpdateRecords = new ArrayList<>();
}
deadUpdateRecords.add(r);
}
// track dead receivers
if (receiverDead) {
if (deadReceivers == null) {
deadReceivers = new ArrayList<>();
}
if (!deadReceivers.contains(receiver)) {
deadReceivers.add(receiver);
}
}
}
// remove dead records and receivers outside the loop
if (deadReceivers != null) {
for (Receiver receiver : deadReceivers) {
removeUpdatesLocked(receiver);
}
}
if (deadUpdateRecords != null) {
for (UpdateRecord r : deadUpdateRecords) {
r.disposeLocked(true);
}
applyRequirementsLocked(provider);
}
}
最终在 receiver.callLocationChangedLocked调用到
public boolean callStatusChangedLocked(String provider, int status, Bundle extras) {
if (mListener != null) {
try {
synchronized (this) {
#AIDL回调到App的位置监听
mListener.onStatusChanged(provider, status, extras);
// call this after broadcasting so we do not increment
// if we throw an exeption.
incrementPendingBroadcastsLocked();
}
} catch (RemoteException e) {
return false;
}
} else {
Intent statusChanged = new Intent();
statusChanged.putExtras(new Bundle(extras));
statusChanged.putExtra(LocationManager.KEY_STATUS_CHANGED, status);
try {
synchronized (this) {
// synchronize to ensure incrementPendingBroadcastsLocked()
// is called before decrementPendingBroadcasts()
mPendingIntent.send(mContext, 0, statusChanged, this, mLocationHandler,
getResolutionPermission(mAllowedResolutionLevel),
PendingIntentUtils.createDontSendToRestrictedAppsBundle(null));
// call this after broadcasting so we do not increment
// if we throw an exeption.
incrementPendingBroadcastsLocked();
}
} catch (PendingIntent.CanceledException e) {
return false;
}
}
return true;
}
这里最终通过AIDL的包装类ListenerTransport里面回调_handleMessage的mListener.onStatusChanged回调到App
- GPS JNI与HAL层流程
在GnssLocationProvider类中静态代码块中调用JNI在JNI中初始化了HAL层级 gnssHal_V1_1服务，在间接的调用HAL层
static {
class_init_native();
}
#目录位置 frameworks\base\services\core\jni\com_android_server_location_GnssLocationProvider.cpp
static void android_location_GnssLocationProvider_class_init_native(JNIEnv* env, jclass clazz) {
gnssHal_V1_1 = IGnss_V1_1::getService();
if (gnssHal_V1_1 == nullptr) {
ALOGD("gnssHal 1.1 was null, trying 1.0");
gnssHal = IGnss_V1_0::getService();
} else {
gnssHal = gnssHal_V1_1;
}
}
最后在使用HAL层调用GPS模块