I am trying to use the proximity search of Geomodel. However, I
am facing a problem, which I am not sure what it is, but I think it is
related to either my PersistentManager or baseQuery. I ran the query,
however, while my database is not empty, I got null results.
Here are my codes:
public class HowToUseGeocell extends TestCase {
...
public int ProximitySearch(double lat, double lon, double distance) {
Point center = new Point(lat, lon);
List<ObjectToSave> objects = null;
PersistenceManager pm = PMF.get().getPersistenceManager();
try{
List<Object> params = new ArrayList<Object>();
params.add("Mahsa");
GeocellQuery baseQuery = new GeocellQuery("Owner ==
OwnerParam", "String OwnerParam", params);
try {
objects = GeocellManager.proximityFetch(center, 40,
distance, ObjectToSave.class, baseQuery, pm);
Assert.assertTrue(objects.size() > 0);
} catch (Exception e) {
// We catch excption here because we have not
configured the PersistentManager (and so the queries won't work)
}
} finally {
pm.close();
}
if (objects == null)
return -3;
else
return objects.size();
}
}
Here is my ObjectToSave class:
@PersistenceCapable(detachable="true")
public class ObjectToSave implements LocationCapable {
@PrimaryKey
@Persistent
private long id;
@Persistent
private double latitude;
@Persistent
private double longitude;
@Persistent
private double altitude;
@Persistent
private List<String> geocells;
@Persistent
private String owner;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public double getLatitude() {
return latitude;
}
public void setLatitude(double latitude) {
this.latitude = latitude;
}
public double getLongitude() {
return longitude;
}
public void setLongitude(double longitude) {
this.longitude = longitude;
}
public double getAltitude() {
return altitude;
}
public void setAltitude(double alt) {
this.altitude = alt;
}
public List<String> getGeocells() {
return geocells;
}
public void setGeocells(List<String> geocells) {
this.geocells = geocells;
}
public String getKeyString() {
return Long.valueOf(id).toString();
}
public Point getLocation() {
return new Point(latitude, longitude);
}
public String getOwner() {
return owner;
}
public void setOwner(String o) {
this.owner = o;
}
}
My PMF class:
public final class PMF {
private static final PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-
optional");
private PMF() {}
public static PersistenceManagerFactory get() {
return pmfInstance;
}
}
My Servlet:
@SuppressWarnings("serial")
public class Test8_Geomodel_GAEServlet extends HttpServlet {
// public static UseGeocell GC = new UseGeocell();
//public final static PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-optional");
public void doGet(HttpServletRequest req, HttpServletResponse
resp)
throws IOException {
doPost(req, resp);
// resp.setContentType("text/plain");
// resp.getWriter().println("Hello, world");
}
public void doPost(HttpServletRequest req, HttpServletResponse
resp)
throws IOException {
HowToUseGeocell gc = new HowToUseGeocell();
List<ObjectToSave> obj = new
ArrayList<ObjectToSave>();
//Read Excel "source file" (which is defined in
web.xml file) &
store it in datastore
ServletContext context = getServletContext();
String file_path = context.getRealPath("LiDAR.xls");
File Myfile = new File(file_path);
Workbook workBook;
int PointNo;
double latitude = 0.0, longitude = 0.0, altitude =
0.0;
String owner = "";
try {
workBook = Workbook.getWorkbook(Myfile);
Sheet sheet = workBook.getSheet(0);
int NumOfColumns = sheet.getColumns();
int NumOfRows = sheet.getRows();
String data;
for(int row = 1; row < NumOfRows; row++) {
for(int col = 0; col < NumOfColumns; col++) {
data = sheet.getCell(col,
row).getContents();
data = sheet.getCell(0,
row).getContents();
PointNo =
Integer.parseInt(data.toString());
data = sheet.getCell(1,
row).getContents();
owner = data;
data = sheet.getCell(2,
row).getContents();
latitude =
Double.parseDouble(data.toString());
data = sheet.getCell(3,
row).getContents();
longitude =
Double.parseDouble(data.toString());
data = sheet.getCell(4,
row).getContents();
altitude =
Double.parseDouble(data.toString());
gc.SaveGeocellsInDatabase(latitude, longitude, altitude, owner);
}
}
} catch (BiffException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//Reading input entries &
executing proximity query
String lat =
req.getParameter("txtlatitude_prox");
String lon =
req.getParameter("txtlongitude_prox");
String dis =
req.getParameter("txtdistance_prox");
double Latitude =
Double.parseDouble(lat);
double Longitude =
Double.parseDouble(lon);
double Distance =
Double.parseDouble(dis);
int size =
gc.ProximitySearch(Latitude, Longitude, Distance);
String res_size =
Integer.toString(size);
resp.setContentType("text/
plain");
resp.getWriter().println(res_size);
}
}
Finally, here is my database (LiDAR.xls file) which is saved in /WAR
and is defined in web.xml file as a resource file as follow:
<resource-files>
<include path="/**.xls" />
</resource-files>
point_no Owner lat
long alt
1 Mahsa 40.46231168 -79.97302985 232.8336705
2 Mahsa 40.46229439 -79.97302785 240.4475744
3 Mahsa 40.46227221 -79.97302604 241.3772144
4 Mahsa 40.46224956 -79.97302421 242.0813024
When I run the program (in a browser), using any lat, lon, & distance,
it returns -3 as the size of the query results, which shows that the
query result was null. I am not sure what I am doing wrong. I really
appreciate if I get help with this.
Also, I appreciate it if someone clarifies what baseQuery is used for.
My understanding is that it first executes a query on the database and
then executes proximity query on the result of the first query
(baseQuery). Is that correct?
Thanks in advance & sorry if my questions sound simple. I am very new
to GAE & java/servlet web development.
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