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Welcome GeoServer Developers

The GeoServer community is the leading example of the power of GeoTools and a source of much of the research and development work benifiting the library as a whole. This is aided by a long standing tradition of pushing as much reusable code as possible out into the GeoTools library.

Catalog for DataStore Management

The GeoServer project is wired together using Spring; giving you an easy way to access the Catalog responsible for managaing DataStores.

DataStores represent physical connections to external servers (often with their own conneciton pool and resources to be cleaned up after). As such it is important that you always use a Catalog to allow GeoServer to know when you are obtaining resources, and clean up the mess if your code happens to crash.

Example of looking up a FeatureTypeInfo for a GeoServer layer:

LayerInfo layerInfo = catalog.getLayerByName(layerName);
if (layerInfo == null) {
    throw new IllegalArgumentException("Unable to locate layer: " + layerName);
}
ResourceInfo resourceInfo = layerInfo.getResource();
if (resourceInfo == null) {
    throw new IllegalArgumentException("Unable to locate ResourceInfo for layer:" + layerName);
}
if (resourceInfo instanceof FeatureTypeInfo) {
    FeatureTypeInfo featureTypeInfo = (FeatureTypeInfo) resourceInfo;
    SimpleFeatureSource featureSource = (SimpleFeatureSource) featureTypeInfo
             .getFeatureSource(null, GeoTools.getDefaultHints());
    ...
}

These data structures provide easy access to the FeatureType and are used to provide additional functionality (such as SQL views). You may also user supplied configuration if you just look at GeoTools data structures (such as the case with a user supplied coordinate reference system).

CoordinateReferenceSystem crs =
   ProjectionPolicy.FORCE_DECLARED == resourceInfo.getProjectionPolicy
      ? resourceInfo.getCRS()
      : resourceInfo.getNativeCRS();

For GeoTools code that needs to look up a FeatureSource can use the Repository interface. GeoServer provides an implementation of Repository (wrapped around the GeoServer catalog).

References: