[Geotools-gt2-users] Problems reading shape files in a web environment

[Thorsten K. <Tho...@pt...>]

> Hello,
>=20
> I have developed a Java web application based on Tomcat which reads =
shape files and imports the geometries into a PostGis database. When =
only a single user imports his data, then so far everything works very =
well. But if two or more concurrent users want to import their shape =
files, then the application crashes.=20
>=20
> The workflow is the following:=20
> A user loads a zip file up to the server. For each zip file, a random =
directory name is created and the zip file is stored in it. After that =
the file will get extracted and the shape file is imported into PostGis. =

>=20
> The error scenario is the following:
> For example user1 loads geo1.zip and user2 loads geo2.zip up to the =
server. Then the two directories and files c:/abc/geo1.zip and =
c:/cba/geo2.zip are created on the server's filesystem. Then the bug =
comes: my shape file reader muddles up the directories and can't find =
the files because it puts the paths together in a wrong way, e.g. =
c:/abc/geo2.zip.
>=20
> I dont't understand why the path is created in this wrong way because =
the requests don't share the same instance of the class ShapeFileReader =
(which is indeed nod thread safe), they create all their own instance.=20
> Perhaps an expert of you can help me to find my mistake!
>=20
> Here is my code of the shape file reader:
> ###########################################
> public class ShapeFileReader {
>=20
> 	private static Logger logger =3D =
Logger.getLogger(ShapeFileReader.class);=20
> 	private URL shapeURL;
> 	private ShapefileDataStore store;
> 	private FeatureSource source;
> 	private FeatureResults fsShape;
> 	private FeatureReader reader;
> =09
> 	/**
> 	 * This method initializes the object.
> 	 * @param path The path to the shape file.
> 	 */
> 	public synchronized void setShapeFilePath(String path) {
> 		File file =3D new File(path);
>=20
> 		try {
> 			this.shapeURL =3D file.toURL();
> 			this.store =3D new ShapefileDataStore(this.shapeURL);
> 			String name =3D store.getTypeNames()[0];
> 			this.source =3D this.store.getFeatureSource(name);
> 			this.fsShape =3D this.source.getFeatures();
> 			this.reader =3D this.fsShape.reader();
> 		} ...
            /**
> 	 * This method collects the geometry values from the shape file.
> 	 * @see GeometryBean
> 	 * @return A Vector of type <code>GeometryBean</code>
> 	 */
> 	public synchronized Vector getGeometries() {
> 		Vector geometries =3D new Vector();
> 		try {
> 			this.reader =3D this.fsShape.reader();
>=20
> 			while (this.reader.hasNext()) {
> 				Feature feature =3D this.reader.next();
> 			=09
> 				MultiPolygon polygon =3D (MultiPolygon) =
feature.getDefaultGeometry();
> 				GeometryBean geometryBean =3D new GeometryBean();
> 				geometryBean.setMultiPolygon(polygon);
> 				geometries.add(geometryBean);
> 			}
> 		}   ...
>  		return geometries;
> }
> ###########################################
>=20
> Here is the relevant code of the servlet which starts the import =
process:
> ###########################################
>  public class ShapeImportServlet extends =
javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
> 	protected void doPost(HttpServletRequest request, HttpServletResponse =
response) throws ServletException, IOException {
> 		// The information about the uploaded zip file, containing the =
directory name and the zip file name
> 		UploadDataBean uploadData =3D (UploadDataBean) =
session.getAttribute("uploadData");
> 		this.processImport(request, uploadData);
> 		...
> 	}
> 	/**
> 	 * This method extracts the necessary information out of the request =
and delegates
> 	 * the database import to a dedicated importer thread. So the servlet =
can display
> 	 * the results immediately while the importer thread does its job.
> 	 * @param request HttpServletRequest.
> 	 * @param uploadData Information about the data which should be =
uploaded.
> 	 */
> 	private void processImport(HttpServletRequest request, UploadDataBean =
uploadData) > {
>=20
> 		String directory =3D uploadData.getDirectoryName() + "/";
> 	=09
> 		Map parameters =3D request.getParameterMap();
> 	=09
> 		Set set =3D parameters.keySet();
> 		Iterator iter =3D set.iterator();
> 	=09
> 		ArrayList filePaths =3D new ArrayList();
> 		ArrayList tableNames =3D new ArrayList();
> 	=09
> 		ArrayList params =3D new ArrayList();
> 	=09
> 		//Evaluate the request parameters
> 		for(Enumeration e=3Drequest.getParameterNames(); =
e.hasMoreElements(); )
> 		{
> 		   params.add((String)e.nextElement());
> 		}=20
> 	=09
> 		String[] parameterNames =3D new String[params.size()];
> 	=09
> 		for (int i =3D 0; i < parameterNames.length; i++) {
> 			parameterNames[i] =3D (String) params.get(i);
> 		}
> 	=09
> 		// Bring the parameter names in the right order to evaluate them =
correctly.
> 		// After sorting, the version, the pk ant the name match.
> 		Arrays.sort(parameterNames);
> 		for (int i =3D 0; i < parameterNames.length; i++) {
> 				tableNames.add(request.getParameter(parameterNames[i]));
> 				filePaths.add(directory + parameterNames[i]);
> 			}
> 		}
> 		if (workflow.equals("1")) {
> 			logger.info("User has chosen to process workflow 1");
> 			new Workflow1Thread(filePaths, tableNames, versions, pks, =
countryID).start();
> 		} else {
> 			System.out.println("---Begin DEBUG");
> 			for (int i =3D 0; i < filePaths.size(); i++) {
> 				System.out.print("filepath " + (String)filePaths.get(i) +
> 								 " tableName " + (String) tableNames.get(i) +=20
> 								 " version " + (String) versions.get(i) + "\n");
> 			}
> 			new Workflow2Thread(filePaths, tableNames, versions, pks, =
countryID).start();
> 		}
> 	}
> 	// This method in the workflow threads starts the reading and import =
of the shape files:
> 	protected void importGeometries() {
> 			// for every geometry table which should be imported
> 			for (int i =3D 0; i < this.pathToShapeFile.size(); i++) {
> 				// ShapeFileAccess mit Pfad zum File benutzen, um die Eintraege zu =
lesen
> 				shapeFileAccess.setShapeFilePath((String) =
this.pathToShapeFile.get(i)); // here the application gets a =
FileNotFoundException!!
> 				Vector geometries =3D shapeFileAccess.getGeometries();
> 			}
> 	}
> }
> ###########################################
> Regards,
> Thorsten