/**
* Writes the opening RDF tag (with namespaces) to the print Writer.
*
* @param out PrintWriter
* @throws IOException
*/
protected void writeRDFHeader(PrintWriter out) throws IOException {
// validate
if (out != null) {
// print opening RDF tag (including namespaces)
out.print("<rdf:RDF ");
// print namespaces
Set<String> keys = namespaces.keySet();
if (keys != null) {
for (String currentKey : keys) {
String currentValue = namespaces.get(currentKey);
if ((currentKey != null) && (currentValue != null)) {
// use entities: xmlns:ns="&ns;"
out.print(NEWLINE + " xmlns:" + currentKey + "=\"&" + currentKey + ";\"");
}
}
}
// close the opening tag (add a space for readability)
out.print(">" + NEWLINE + NEWLINE);
} else {
throw new IllegalArgumentException("Cannot write to null Writer.");
}
}
/**
* If the URI contains the URI of a known namespace, it is replaced.
*
* @param original original URI.
* @return new URI with namespace references.
*/
protected String replaceNamespace(String original) throws GraphException {
// value to be returned
String uri = original;
// validate URI (only replace uri's with fragments)
if (original != null) {
// replace any URI occurances with namespace prefixes
for (String currentKey : namespaces.keySet()) {
String currentValue = namespaces.get(currentKey);
// validate the Objects
if ((currentKey != null) && (currentValue != null)) {
// if the entire namespace is used, replace it with an entity
if (original.equals(currentValue)) {
uri = "&" + currentKey + ";";
} else if (original.startsWith(currentValue.toString())) {
// replace with namespace
uri = original.replaceAll(currentValue.toString(), currentKey + ":");
}
}
}
}
// return the URI with any collection/container items renamed
return replaceCollection(uri);
}
/**
* Writes the XML Entities (used for namespaces) to the print Writer.
*
* @param out PrintWriter
* @throws IOException
*/
protected void writeXMLEntities(PrintWriter out) throws IOException {
// validate
if (out != null) {
// print opening DOCTYPE DECLARATION tag
out.print(NEWLINE + "<!DOCTYPE rdf:RDF [");
// print namespaces
Set<String> keys = namespaces.keySet();
if (keys != null) {
for (String currentKey : keys) {
String currentValue = namespaces.get(currentKey);
if ((currentKey != null) && (currentValue != null)) {
// write as: <!ENTITY ns 'http://example.org/abc#'>
out.print(NEWLINE + " <!ENTITY " + currentKey + " '" + currentValue + "'>");
}
}
}
// close the opening tag (add a space for readability)
out.print("]>" + NEWLINE + NEWLINE);
} else {
throw new IllegalArgumentException("Cannot write to null Writer.");
}
}