Java Doc for Configuration.java in  » GIS » GeoTools-2.4.1 » org » geotools » xml » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Implementations have the following responsibilites:

• Configuration of bindings.
• Configuration of context used by bindings.
• Supplying specialized handlers for looking up schemas.
• Supplying specialized handlers for parsing schemas.
• Declaring dependencies on other configurations

Dependencies

Configurations have dependencies on one another, that result from teh fact that one schema imports another. Configuration dependencies are transitive. Each configuration should declare all dependencies in the constructor using the Configuration.addDependency(Configuration) method.

 class MyConfiguration extends Configuration {
 public MyConfiguration() {
 super();
 addDependency( new FooConfiguration() );
 addDependency( new BarConfiguration() );
 }
 ...
 }
 

Binding Configuration

In able for a particular binding to be found during a parse, the configuration must first populate a container with said binding. This can be done by returning the appropriate instance of org.geotools.xml.BindingConfiguration in Configuration.getBindingConfiguration() :

 
 BindingConfiguration getBindingConfiguration() {
 return new MyBindingConfiguration();
 }
 
 

Context Configuration

Many bindings have dependencies on other types of objects. The pattern used to satisfy these dependencies is known as Constructor Injection. Which means that any dependencies a binding has is passed to it in its constructor. For instance, the following binding has a dependency on java.util.List.

 
 class MyBinding implements SimpleBinding {
 List list;
 public MyBinding(List list) {
 this.list = list;
 }
 }
 
 

 
 class MyConfiguration extends Configuration {
 ....
 void configureContext(MutablePicoContainer container) {
 container.registerComponentImplementation(ArrayList.class);
 }
 }
 
 

Schema Resolution

XML instance documents often contain schema uri references that are invalid with respect to the parser, or non-existant. A configuration can supply specialized look up classes to prevent the parser from following an invalid uri and prevent any errors that may occur as a result.

An instance of org.eclipse.xsd.util.XSDSchemaLocationResolver can be used to override a schemaLocation referencing another schema. This can be useful when the entity parsing an instance document stores schemas in a location unkown to the entity providing hte instance document.

An instance of org.eclipse.xsd.util.XSDSchemaLocator can be used to provide an pre-parsed schema and prevent the parser from parsing a schemaLocation manually. This can be useful when an instance document does not supply a schemaLocation for the targetNamespace of the document.

 
 class MyConfiguration implements Configuration {
 XSDSchemaLocationResolver getSchemaLocationResolver() {
 return new MySchemaLocationResolver();
 }
 XSDSchemaLocator getSchemaLocator() {
 return new MySchemaLocator();
 }
 }
 
 

The XSDSchemaLocator and XSDSchemaLocationResolver implementations are used in a couple of scenarios. The first is when the schemaLocation attribute of the root element of the instance document is being parsed. The schemaLocation attribute has the form:

 
 schemaLocation="namespace location namespace location ..."
 
 

 
 <import namespace="" schemaLocation=""/>
 
 

 
 <include schemaLocation="">
 
 

The context satisifies any depenencencies needed by a binding.

To set a parser property:

 Configuration configuration = ...
 configuration.getProperties().add( Parser.Properties....

This method should be overridden to return such an instance.

This method may be overriden to return such an instance.

Any dependent schemas should be added in sublcass constructor. The xml schema dependency does not have to be added.

This method should only be called from the constructor.

The return list contains no duplicates.

The context satisifies any depenencencies needed by a binding. This is often a factory used to create something.

This method should be overriden. The default implementation does nothing.

Subclasses may override this method, the default implementation returns a new instance of SchemaLocator .

To set a parser property:

 Configuration configuration = ...
 configuration.getProperties().add( Parser.Properties.... );
 

For schema which are defined by multiple files, this method should return the base schema which includes all other files that define the schema.

This method should be overridden to return such an instance. The default implemntation returns null

This method may be overriden to return such an instance. The default delegates to Configuration.createSchemaLocator() to and caches the restult. This method may return null to indicate that no such locator should be used.