手动打开GPS

	private void openGPSSettings() 
    { 
	    LocationManager alm = (LocationManager)this.getSystemService( Context.LOCATION_SERVICE ); 
	    if( alm.isProviderEnabled(android.location.LocationManager.GPS_PROVIDER ) ) 
	    { 
	    	Toast.makeText( this, "GPS is already on", Toast.LENGTH_SHORT ).show(); 
	    } 
	    else 
	    { 
		    Toast.makeText( this, "Please turn on GPS", Toast.LENGTH_SHORT ).show(); 
		    Intent myIntent = new Intent( Settings.ACTION_SECURITY_SETTINGS ); 
		    startActivity(myIntent); 
	    } 
    }