// GET /predictions2
// GET /predictions2?id=1
// If the HTTP Accept header is set to application/json (or an equivalent
// such as text/x-json), the response is JSON and XML otherwise.
public void doGet(HttpServletRequest request, HttpServletResponse response) {
String param = request.getParameter("id");
Integer key = (param == null) ? null : new Integer(param.trim());
// Check user preference for XML or JSON by inspecting
// the HTTP headers for the Accept key.
boolean json = false;
String accept = request.getHeader("accept");
if (accept != null && accept.contains("json")) json = true;
// If no query string, assume client wants the full list.
if (key == null) {
ConcurrentMap<Integer, Prediction> map = predictions.getPredictions();
// Sort the map's values for readability.
Object[] list = map.values().toArray();
Arrays.sort(list);
String xml = predictions.toXML(list);
sendResponse(response, xml, json);
}
// Otherwise, return the specified Prediction.
else {
Prediction prediction = predictions.getPredictions().get(key);
if (prediction == null) { // no such prediction
String msg = key + " does not map to a prediction.\n";
sendResponse(response, predictions.toXML(msg), false);
} else { // requested Prediction found
sendResponse(response, predictions.toXML(prediction), json);
}
}
}
// DELETE /predictions2?id=1
public void doDelete(HttpServletRequest request, HttpServletResponse response) {
String param = request.getParameter("id");
Integer key = (param == null) ? null : new Integer(param.trim());
// Only one Prediction can be deleted at a time.
if (key == null) throw new HTTPException(HttpServletResponse.SC_BAD_REQUEST);
try {
predictions.getPredictions().remove(key);
String msg = "Prediction " + key + " removed.\n";
sendResponse(response, predictions.toXML(msg), false);
} catch (Exception exception) {
throw new HTTPException(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
// PUT /predictions
// HTTP body should contain at least two keys: the prediction's id
// and either who of what
public void doPut(HttpServletRequest request, HttpServletResponse response) {
/*
* A workaround is necessary for a PUT request because neither Tomcat
* nor Jetty generates a workable parameter map for this HTTP verb.
*/
String key = null;
String rest = null;
boolean who = false;
/* Let the hack begin */
try {
BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
String data = br.readLine();
/*
* To simplify the hack, assume that the PUT request has exactly two
* parameters: the id and either who or what. Assume further, that
* the id comes first. From the client side, a hash character #
* separates the id and the who/what, e.g, id=33#who=Homer Allision
*/
String[] args = data.split("#"); // id in args[0], rest in args[1]
String[] parts1 = args[0].split("="); // id = parts[1]
key = parts1[1];
String[] parts2 = args[1].split("="); // parts2[0] is key
if (parts2[0].contains("who")) who = true;
rest = parts2[1];
} catch (Exception excecao) {
throw new HTTPException(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
// If no key, then the request is ill formed.
if (key == null) throw new HTTPException(HttpServletResponse.SC_BAD_REQUEST);
// Look up the specified prediction.
Prediction prediction = predictions.getPredictions().get(new Integer(key.trim()));
if (prediction == null) { // not found?
String msg = key + "does not map to a Prediction.\n";
sendResponse(response, predictions.toXML(msg), false);
} else { // found
if (rest == null) {
throw new HTTPException(HttpServletResponse.SC_BAD_REQUEST);
}
// Do the editing,
else {
if (who) prediction.setWho(rest);
else prediction.setWhat(rest);
String msg = "Prediction " + key + " has been edited.\n";
sendResponse(response, predictions.toXML(msg), false);
}
}
}
