/**
* 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.");
}
}
/**
* 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.");
}
}
/**
* Writes the opening tag for the subject
*
* @param graph JRDFGraph
* @param subject SubjectNode
* @param writer PrintWriter
* @throws GraphException
*/
protected void writeClosingTag(Graph graph, BlankNode subject, PrintWriter writer)
throws GraphException {
ObjectNode subjectType = this.getSubjectType(graph, subject);
// only display as a subject if it can be found
if (subjectType != null) {
// closing tag
writer.print(" </" + this.getURI(subjectType) + ">" + NEWLINE);
} else {
// closing tag
writer.print(" </" + RDF_PREFIX + ":Description>" + NEWLINE);
}
}
/**
* Writes the opening tag for the subject
*
* @param graph JRDFGraph
* @param subject SubjectNode
* @param writer PrintWriter
* @throws GraphException
*/
protected void writeOpeningTag(Graph graph, SubjectNode subject, PrintWriter writer)
throws GraphException {
if (writer != null) {
// write the subject type and rdf:about
if (subject != null) {
// open tag - BlankNodes are a special case
if (subject instanceof BlankNode) {
this.writeOpeningTag(graph, (BlankNode) subject, writer);
} else {
writer.print(
" <"
+ RDF_PREFIX
+ ":Description "
+ RDF_PREFIX
+ ":about=\""
+ this.getNodeString(subject)
+ "\">"
+ NEWLINE);
}
} else {
throw new IllegalArgumentException(
"Could not write opening tag for subject. Subject Node is null.");
}
}
}
/**
* Writes the opening tag for the subject
*
* @param graph JRDFGraph
* @param subject SubjectNode
* @param writer PrintWriter
* @throws GraphException
*/
protected void writeClosingTag(Graph graph, SubjectNode subject, PrintWriter writer)
throws GraphException {
// Blank Nodes are written differently
if (subject instanceof BlankNode) {
this.writeClosingTag(graph, (BlankNode) subject, writer);
} else {
// closing tag
writer.print(" </" + RDF_PREFIX + ":Description>" + NEWLINE);
}
}