Classes for reading the shape format

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The ilog.views.maps.format.shapefile package includes the following classes:

IlvShapeFileReader

This class implements the IlvMapFeatureIterator interface and allows you to read .shp , .dbf and .shx files. Since Shapefiles provide no information on the projection system used, this reader is not georeferenced. This reader uses the two specialized readers described below. Its getNextFeature getNext method merges the information generated by these specialized readers into a single map feature.
IlvSHPReader

This class implements the IlvMapFeatureIterator interface. This reader only reads .shp files.
IlvDBFReader: reads .dbf files.
IlvShapeFileIndex: reads .shx files.
IlvShapeSpatialIndex: reads maps spatial index .idx files.

The IlvSHPReader class

The geometries stored in Shapefiles are not necessarily 2-D objects. Each point that makes up a shape object can be associated with measurements, or with measurements and an elevation.

Measurements are stored in an attribute of type IlvAttributeArray, which itself is stored in the map feature attribute of index 0.

The following are the shape types that are associated with measurements:

POINTZ
POLYLINEZ
POLYGONZ
MULTIPOINTZ
POINTM
POLYLINEM
POLYGONM
MULTIPOINTM

Elevations are stored in an attribute of type IlvAttributeArray, which itself is stored in the map feature attribute of index 1.

The following are the shape types that are associated with measurements and elevations:

POINTZ
POLYLINEZ
POLYGONZ
MULTIPOINTZ

Since the JViews Maps package does not have a predefined geometry to represent shape objects of type MULTIPATCH , which are essentially used for 3-D rendering, these are ignored. It is possible, however, to modify this behavior by subtyping the class IlvShapeSHPReader . Since shape objects are read in protected methods, modifying the reader to include new geometries requires minimal effort.

The IlvDBFReader class

This reader is used exclusively for reading a file of the .dbf format. It can be used to iterate over a file as follows:

 try {
       IlvDBFReader reader = new IlvDBFReader("myFile.dbf");
       IlvFeatureAttributeProperty attributes = reader.getNextRecord();
       while (attributes != null) {
         // Process attributes.
         ...
        attributes = reader.getNextRecord();
       }
    } catch (Exception e) {
       e.printStackTrace();
    }

If the reader has been created from a file and not from a URL, you can access map feature attributes directly by specifying their record number:

reader.readRecord(index);

The IlvShapeFileReader class

This reader reads the .shp file storing geometries and the .dbf file storing attributes simultaneously, and merges the information into a single IlvMapFeature object.

It can be instantiated in one of three ways:

By specifying the name of the .dbf and .shp files.
By specifying the URL of these two files.
By specifying an IlvDBFReader and IlvSHPReader object directly.

This is useful, for example, when using a derived IlvSHPReader object.

Current section

The shapefile reader and writer