GPS简单模拟

注册回调 LocationListener，listener 被封装在 receiver 中

    @Overridepublic void requestLocationUpdates(LocationRequest request, ILocationListener listener,PendingIntent intent, String packageName) {...Receiver receiver;if (intent != null) {receiver = getReceiverLocked(intent, pid, uid, packageName, workSource,hideFromAppOps);} else {receiver = getReceiverLocked(listener, pid, uid, packageName, workSource,hideFromAppOps);}requestLocationUpdatesLocked(sanitizedRequest, receiver, uid, packageName);}@GuardedBy("mLock")private void requestLocationUpdatesLocked(LocationRequest request, Receiver receiver,int uid, String packageName) {UpdateRecord record = new UpdateRecord(name, request, receiver);UpdateRecord oldRecord = receiver.mUpdateRecords.put(name, record);if (oldRecord != null) {oldRecord.disposeLocked(false);}if (!provider.isUseableLocked() && !isSettingsExemptLocked(record)) {receiver.callProviderEnabledLocked(name, false);}applyRequirementsLocked(name);receiver.updateMonitoring(true);}

调用回调 reportLocation() --> handleLocationChangedLocked --> receiver.callLocationChangedLocked

hal会从驱动读取GPS信息然后调用 --> jni 的函数 reportLocation() 上报

void Gnss::locationCb(GpsLocation* location) {android::hardware::gnss::V1_0::GnssLocation gnssLocation = convertToGnssLocation(location);auto ret = sGnssCbIface->gnssLocationCb(gnssLocation);
}template<class T>
Return<void> GnssCallback::gnssLocationCbImpl(const T& location) {JNIEnv* env = getJniEnv();jobject jLocation = translateGnssLocation(env, location);env->CallVoidMethod(mCallbacksObj,method_reportLocation,boolToJbool(hasLatLong(location)),jLocation);checkAndClearExceptionFromCallback(env, __FUNCTION__);env->DeleteLocalRef(jLocation);return Void();
}

JNI获取GNSS HAL接口

/* Initializes the GNSS service handle. */
static void android_location_GnssLocationProvider_set_gps_service_handle() {gnssHal = IGnss_V1_0::getService();
}

获取GNSS接口，添加CallBack

// hardware/interfaces/gnss/1.0/default/Gnss.cppGnss::Gnss(gps_device_t* gnssDevice) :mDeathRecipient(new GnssHidlDeathRecipient(this)) {mGnssIface = gnssDevice->get_gps_interface(gnssDevice);
}Return<bool> Gnss::setCallback(const sp<IGnssCallback>& callback)  {...return (mGnssIface->init(&sGnssCb) == 0);
}

结构体对齐 init函数调用的实际是qemu_gps_init

hardware/libhardware/include/hardware/gps.h
/** Represents the standard GPS interface. */
typedef struct {size_t          size;int   (*init)( GpsCallbacks* callbacks );...
} GpsInterface;static const GpsInterface  qemuGpsInterface = {sizeof(GpsInterface),qemu_gps_init,...
};

device/generic/goldfish/gps/gps_qemu.c

NmeaReader 读取32字节,解析在nmea_reader_addc中

// 
else if (fd == gps_fd)
{char  buff[32];D("gps fd event");for (;;) {int  nn, ret;ret = read( fd, buff, sizeof(buff) );if (ret < 0) {if (errno == EINTR)continue;if (errno != EWOULDBLOCK)ALOGE("error while reading from gps daemon socket: %s:", strerror(errno));break;}D("received %d bytes: %.*s", ret, ret, buff);for (nn = 0; nn < ret; nn++)nmea_reader_addc( reader, buff[nn] );}D("gps fd event end");
}

一些字段含义

r->sv_status.num_svs = 6;  //卫星数量
r->sv_status_changed = 1; //状态回调
r->sv_status.used_in_fix_mask |= (1 << (r->sv_status.num_svs));
r->fix.accuracy = 8.0;  //精度
r->fix.timestamp = 1685782786; //时间戳
r->fix.latitude = strtod(propbuf_latitude,NULL);
r->fix.longitude = strtod(propbuf_longitude,NULL);
r->fix.flags    |= GPS_LOCATION_HAS_LAT_LONG;
r->fix.flags   |= GPS_LOCATION_HAS_ACCURACY;
D("lat : %f  lon : %f ",  r->fix.latitude, r->fix.longitude);

实现一个最简单的虚拟定位模拟

diff --git a/frameworks/base/services/core/java/com/android/server/LocationManagerService.java b/frameworks/base/services/core/java/com/android/server/LocationManagerService.java
index 90e467034e..0f4a2e51d1 100644
--- a/frameworks/base/services/core/java/com/android/server/LocationManagerService.java
+++ b/frameworks/base/services/core/java/com/android/server/LocationManagerService.java
@@ -98,6 +98,7 @@ import com.android.internal.location.ProviderRequest;import com.android.internal.util.ArrayUtils;import com.android.internal.util.DumpUtils;import com.android.internal.util.Preconditions;import com.android.server.location.AbstractLocationProvider;import com.android.server.location.ActivityRecognitionProxy;import com.android.server.location.CallerIdentity;
@@ -2553,12 +2554,36 @@ public class LocationManagerService extends ILocationManager.Stub {hideFromAppOps);}requestLocationUpdatesLocked(sanitizedRequest, receiver, uid, packageName);
+                requestReportLocation();} finally {Binder.restoreCallingIdentity(identity);}}}+    public void requestReportLocation() {
+        Location loc = createLocation(121.54611623716278, 25.094571969899793);
+        LocationProvider gpsProvider = getLocationProviderLocked(GPS_PROVIDER);
+        if  (loc != null && gpsProvider != null) {
+            gpsProvider.onReportLocation(loc);
+        }
+    }
+
+    private Location createLocation(double longitude, double latitude) {
+        Location location = new Location(LocationManager.GPS_PROVIDER);
+        location.setLongitude(longitude);
+        location.setLatitude(latitude);
+        location.setTime(System.currentTimeMillis());
+        location.setAccuracy(5.0f);
+        location.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());
+        return location;
+    }