/**
* Constructor that configures the cache of ResponseWriter objects.
*
* @param conf The Nutch configuration object.
*/
public ResponseWriters(Configuration conf) {
// get the cache and the cache key
String cacheKey = ResponseWriter.class.getName();
ObjectCache objectCache = ObjectCache.get(conf);
this.responseWriters = (Map<String, ResponseWriter>) objectCache.getObject(cacheKey);
// if already populated do nothing
if (this.responseWriters == null) {
try {
// get the extension point and all ResponseWriter extensions
ExtensionPoint point =
PluginRepository.get(conf).getExtensionPoint(ResponseWriter.X_POINT_ID);
if (point == null) {
throw new RuntimeException(ResponseWriter.X_POINT_ID + " not found.");
}
// populate content type on the ResponseWriter classes, each response
// writer can handle more than one response type
Extension[] extensions = point.getExtensions();
Map<String, ResponseWriter> writers = new HashMap<String, ResponseWriter>();
for (int i = 0; i < extensions.length; i++) {
Extension extension = extensions[i];
ResponseWriter writer = (ResponseWriter) extension.getExtensionInstance();
String[] responseTypes = extension.getAttribute("responseType").split(",");
String contentType = extension.getAttribute("contentType");
writer.setContentType(contentType);
for (int k = 0; k < responseTypes.length; k++) {
writers.put(responseTypes[k], writer);
}
}
// set null object if no writers, otherwise set the writers
if (writers == null) {
objectCache.setObject(cacheKey, new HashMap<String, ResponseWriter>());
} else {
objectCache.setObject(cacheKey, writers);
}
} catch (PluginRuntimeException e) {
throw new RuntimeException(e);
}
// set the response writers map
this.responseWriters = (Map<String, ResponseWriter>) objectCache.getObject(cacheKey);
}
}
/**
* Returns the appropriate {@link Protocol} implementation for a url.
*
* @param urlString Url String
* @return The appropriate {@link Protocol} implementation for a given {@link URL}.
* @throws ProtocolNotFound when Protocol can not be found for urlString
*/
public ProtocolHbase getProtocol(String urlString) throws ProtocolNotFound {
ObjectCache objectCache = ObjectCache.get(conf);
try {
URL url = new URL(urlString);
String protocolName = url.getProtocol();
String cacheId = ProtocolHbase.X_POINT_ID + protocolName;
if (protocolName == null) throw new ProtocolNotFound(urlString);
if (objectCache.getObject(cacheId) != null) {
return (ProtocolHbase) objectCache.getObject(cacheId);
} else {
Extension extension = findExtension(protocolName);
if (extension == null) {
throw new ProtocolNotFound(protocolName);
}
ProtocolHbase protocol = (ProtocolHbase) extension.getExtensionInstance();
objectCache.setObject(cacheId, protocol);
return protocol;
}
} catch (MalformedURLException e) {
throw new ProtocolNotFound(urlString, e.toString());
} catch (PluginRuntimeException e) {
throw new ProtocolNotFound(urlString, e.toString());
}
}