/**
* Returns the array of providers which meet the user supplied set of filters. The filter must be
* supplied in one of two formats: <nl>
* <li>CRYPTO_SERVICE_NAME.ALGORITHM_OR_TYPE
*
* <p>for example: "MessageDigest.SHA" The value associated with the key must be an empty
* string.
* <li>CRYPTO_SERVICE_NAME.ALGORITHM_OR_TYPE ATTR_NAME:ATTR_VALUE
*
* <p>for example: "Signature.MD2withRSA KeySize:512" where "KeySize:512" is the value of the
* filter map entry. </nl>
*
* @param filter case-insensitive filter.
* @return the providers which meet the user supplied string filter {@code filter}. A {@code null}
* value signifies that none of the installed providers meets the filter specification.
* @throws InvalidParameterException if an unusable filter is supplied.
* @throws NullPointerException if {@code filter} is {@code null}.
*/
public static synchronized Provider[] getProviders(Map<String, String> filter) {
if (filter == null) {
throw new NullPointerException();
}
if (filter.isEmpty()) {
return null;
}
java.util.List<Provider> result = Services.getProvidersList();
Set<Entry<String, String>> keys = filter.entrySet();
Map.Entry<String, String> entry;
for (Iterator<Entry<String, String>> it = keys.iterator(); it.hasNext(); ) {
entry = it.next();
String key = entry.getKey();
String val = entry.getValue();
String attribute = null;
int i = key.indexOf(' ');
int j = key.indexOf('.');
if (j == -1) {
throw new InvalidParameterException();
}
if (i == -1) { // <crypto_service>.<algorithm_or_type>
if (val.length() != 0) {
throw new InvalidParameterException();
}
} else { // <crypto_service>.<algorithm_or_type> <attribute_name>
if (val.length() == 0) {
throw new InvalidParameterException();
}
attribute = key.substring(i + 1);
if (attribute.trim().length() == 0) {
throw new InvalidParameterException();
}
key = key.substring(0, i);
}
String serv = key.substring(0, j);
String alg = key.substring(j + 1);
if (serv.length() == 0 || alg.length() == 0) {
throw new InvalidParameterException();
}
Provider p;
for (int k = 0; k < result.size(); k++) {
try {
p = result.get(k);
} catch (IndexOutOfBoundsException e) {
break;
}
if (!p.implementsAlg(serv, alg, attribute, val)) {
result.remove(p);
k--;
}
}
}
if (result.size() > 0) {
return result.toArray(new Provider[result.size()]);
}
return null;
}
