https://blog.csdn.net/aggresss/article/details/54318905
这一期我们来做一个简单的实验，实验的前提是要对当作开发板的手机有从源码编译的能力，如果还没有实现，请参考前几期内容。上一期我们分析了GPS定位数据是如何在Android中逐层上报的，如果不实践一下还是觉得不太直观。
不多说了，直接修改文件，进入到Android的源码目录，修改这个文件：
frameworks/base/services/core/Java/com/android/server/location/GpsLocationProvider.java
/**
* called from native code to update our position.
*/
private void reportLocation(int flags, double latitude, double longitude, double altitude,
float speed, float bearing, float accuracy, long timestamp) {
if (VERBOSE) Log.v(TAG, "reportLocation lat: " + latitude + " long: " + longitude +
" timestamp: " + timestamp);
synchronized (mLocation) {
mLocationFlags = flags;
if ((flags & LOCATION_HAS_LAT_LONG) == LOCATION_HAS_LAT_LONG) {
mLocation.setLatitude(latitude);
mLocation.setLongitude(longitude);
mLocation.setTime(timestamp);
// It would be nice to push the elapsed real-time timestamp
// further down the stack, but this is still useful
mLocation.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());
}
if ((flags & LOCATION_HAS_ALTITUDE) == LOCATION_HAS_ALTITUDE) {
mLocation.setAltitude(altitude);
} else {
mLocation.removeAltitude();
}
if ((flags & LOCATION_HAS_SPEED) == LOCATION_HAS_SPEED) {
mLocation.setSpeed(speed);
} else {
mLocation.removeSpeed();
}
if ((flags & LOCATION_HAS_BEARING) == LOCATION_HAS_BEARING) {
mLocation.setBearing(bearing);
} else {
mLocation.removeBearing();
}
if ((flags & LOCATION_HAS_ACCURACY) == LOCATION_HAS_ACCURACY) {
mLocation.setAccuracy(accuracy);
} else {
mLocation.removeAccuracy();
}
mLocation.setExtras(mLocationExtras);
try {
mILocationManager.reportLocation(mLocation, false);
} catch (RemoteException e) {
Log.e(TAG, "RemoteException calling reportLocation");
}
}这个函数就是Framework层上报GPS数据的，只要修改这个函数的GPS数据，那么手机的APP层就会收到这个数据，我们小做改动:
/**
* called from native code to update our position.
*/
private void reportLocation(int flags, double latitude, double longitude, double altitude,
float speed, float bearing, float accuracy, long timestamp) {
if (VERBOSE) Log.v(TAG, "reportLocation lat: " + latitude + " long: " + longitude +
" timestamp: " + timestamp);
synchronized (mLocation) {
mLocationFlags = flags;
if ((flags & LOCATION_HAS_LAT_LONG) == LOCATION_HAS_LAT_LONG) {
double vir_lat = latitude + 20;
double vir_lon = longitude +20;
mLocation.setLatitude(vir_lat);
mLocation.setLongitude(vir_lon);
mLocation.setTime(timestamp);
// It would be nice to push the elapsed real-time timestamp
// further down the stack, but this is still useful
mLocation.setElapsedRealtimeNanos(SystemClock.elapsedRealtimeNanos());
}
if ((flags & LOCATION_HAS_ALTITUDE) == LOCATION_HAS_ALTITUDE) {
mLocation.setAltitude(altitude);
} else {
mLocation.removeAltitude();
}
if ((flags & LOCATION_HAS_SPEED) == LOCATION_HAS_SPEED) {
mLocation.setSpeed(speed);
} else {
mLocation.removeSpeed();
}
if ((flags & LOCATION_HAS_BEARING) == LOCATION_HAS_BEARING) {
mLocation.setBearing(bearing);
} else {
mLocation.removeBearing();
}
if ((flags & LOCATION_HAS_ACCURACY) == LOCATION_HAS_ACCURACY) {
mLocation.setAccuracy(accuracy);
} else {
mLocation.removeAccuracy();
}
mLocation.setExtras(mLocationExtras);
try {
mILocationManager.reportLocation(mLocation, false);
} catch (RemoteException e) {
Log.e(TAG, "RemoteException calling reportLocation");
}
}
仔细比对会发现，我们把上报的经纬度都加了20度。修改后，保存并重新编译Android源码，然后开机后打开一个地图软件：
可以看到，直接漂移出国到了俄罗斯，下一期我们来进一步实践，做一个完整的方案，可以想飘到哪就飘到哪。