/**
* Converts a map of results to a String JSON representation for it
*
* @param map a map that matches properties with an ArrayList of values
* @return the JSON representation for the map, as a String
*/
private String mapToString(Map<String, ArrayList<String>> map) {
StringBuilder result = new StringBuilder("{");
for (Map.Entry<String, ArrayList<String>> entry : map.entrySet()) {
ArrayList<String> value = entry.getValue();
if (value.size() == 1)
result.append(String.format("\"%s\" : %s,\n", entry.getKey(), value.get(0)));
else result.append(String.format("\"%s\" : %s,\n", entry.getKey(), value.toString()));
}
result.setCharAt(result.length() - 2, '}');
return result.toString();
}
// convert InputStream to String
private static String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
/**
* Build a query returning all triples in which members of uris are the subjects of the triplets.
*
* <p>If toDescribeURIs is true the query will automatically add logic to retrieve the labels
* directly from the SPARQL endpoint.
*
* @param uris URIs for queried resources
* @return a CONSTRUCT query string
*/
private String getSyncQueryStr(Iterable<String> uris) {
StringBuilder uriSetStrBuilder = new StringBuilder();
String delimiter = "";
uriSetStrBuilder.append("(");
for (String uri : uris) {
uriSetStrBuilder.append(delimiter).append(String.format("<%s>", uri));
delimiter = ", ";
}
uriSetStrBuilder.append(")");
String uriSet = uriSetStrBuilder.toString();
/* Get base triplets having any element from uris as subject */
StringBuilder queryBuilder = new StringBuilder();
queryBuilder
.append("CONSTRUCT { ?s ?p ?o } WHERE {")
.append("{?s ?p ?o")
.append(String.format(" . FILTER (?s in %s )", uriSet));
/* Perform uri label resolution only if desired */
if (uriDescriptionList.isEmpty()) {
queryBuilder.append("}}");
return queryBuilder.toString();
}
/* Filter out properties having a label */
int index = 0;
for (String prop : uriDescriptionList) {
index++;
String filterTemplate = " . OPTIONAL { ?o <%s> ?o%d } " + " . FILTER(!BOUND(?o%d))";
queryBuilder.append(String.format(filterTemplate, prop, index, index));
}
queryBuilder.append("}");
/* We need this redundant clause as UNION queries can't handle sub-selects
* without a prior clause.
*/
String redundantClause =
"<http://www.w3.org/2000/01/rdf-schema#Class> "
+ "a <http://www.w3.org/2000/01/rdf-schema#Class>";
/* Add labels for filtered out properties */
for (String prop : uriDescriptionList) {
/* Resolve ?o as str(?label) for the resource ?res
* label is taken as being ?res <prop> ?label
*
* We need to take str(?label) in order to drop
* language references of the terms so that the document
* is indexed with a language present only in it's top-level
* properties.
*
* As some Virtuoso versions do not allow the usage
* of BIND so we have to create a sub-select in order to bind
* ?o to str(?label)
*
* The sub-select works only with a prior clause.
* We are using a redundant clause that is always true
*/
String partQueryTemplate =
" UNION "
+ "{ "
+ redundantClause
+ " . "
+ "{ SELECT ?s ?p (str(?label) as ?o) { "
+ " ?s ?p ?res"
+ " . FILTER (?s in %s)"
+ " . ?res <%s> ?label }}}";
queryBuilder.append(String.format(partQueryTemplate, uriSet, prop));
}
queryBuilder.append("}");
return queryBuilder.toString();
}