结合重力感应器来计算手机移动的方位
public void onSensorChanged( SensorEvent event ) { // If we don't have a Location, we break out if ( LocationObj == null ) return; float azimuth = event.values[0]; float baseAzimuth = azimuth; GeomagneticField geoField = new GeomagneticField( Double .valueOf( LocationObj.getLatitude() ).floatValue(), Double .valueOf( LocationObj.getLongitude() ).floatValue(), Double.valueOf( LocationObj.getAltitude() ).floatValue(), System.currentTimeMillis() ); azimuth -= geoField.getDeclination(); // converts magnetic north into true north // Store the bearingTo in the bearTo variable float bearTo = LocationObj.bearingTo( destinationObj ); // If the bearTo is smaller than 0, add 360 to get the rotation clockwise. if (bearTo < 0) { bearTo = bearTo + 360; } //This is where we choose to point it float direction = bearTo - azimuth; // If the direction is smaller than 0, add 360 to get the rotation clockwise. if (direction < 0) { direction = direction + 360; } rotateImageView( arrow, R.drawable.arrow, direction ); //Set the field String bearingText = "N"; if ( (360 >= baseAzimuth && baseAzimuth >= 337.5) || (0 <= baseAzimuth && baseAzimuth <= 22.5) ) bearingText = "N"; else if (baseAzimuth > 22.5 && baseAzimuth < 67.5) bearingText = "NE"; else if (baseAzimuth >= 67.5 && baseAzimuth <= 112.5) bearingText = "E"; else if (baseAzimuth > 112.5 && baseAzimuth < 157.5) bearingText = "SE"; else if (baseAzimuth >= 157.5 && baseAzimuth <= 202.5) bearingText = "S"; else if (baseAzimuth > 202.5 && baseAzimuth < 247.5) bearingText = "SW"; else if (baseAzimuth >= 247.5 && baseAzimuth <= 292.5) bearingText = "W"; else if (baseAzimuth > 292.5 && baseAzimuth < 337.5) bearingText = "NW"; else bearingText = "?"; fieldBearing.setText(bearingText);}