@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
resp.setContentType("text/html");
resp.getWriter().println("<html><body>");
String keyname = req.getParameter("keyname");
String value = req.getParameter("value");
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
// Using the synchronous cache.
MemcacheService syncCache = MemcacheServiceFactory.getMemcacheService();
syncCache.setErrorHandler(ErrorHandlers.getConsistentLogAndContinue(Level.INFO));
// display every element of kind TaskData for /datastore
if (req.getParameterMap().isEmpty()) {
// querying from datastore
resp.getWriter().println("<h3>Datastore results:</h3>");
List<String> listOfKeys = new ArrayList<String>();
Query q = new Query("TaskData");
PreparedQuery pq = datastore.prepare(q);
for (Entity result : pq.asIterable()) {
String datastore_key = result.getKey().getName();
String taskData_value = (String) result.getProperty("value");
Date taskData_date = (Date) result.getProperty("date");
resp.getWriter()
.println(
"<p>keyname = "
+ datastore_key
+ " value = "
+ taskData_value
+ " date = "
+ taskData_date.toString()
+ "</p>");
listOfKeys.add(datastore_key);
}
// check which of the keys exist in memcache
String memcache_value;
resp.getWriter().println("<h3>Memcache results:</h3>");
for (String datastore_key : listOfKeys) {
memcache_value = (String) syncCache.get(datastore_key);
if (memcache_value != null) {
// String decoded = new String(memcache_value, "UTF-8");
resp.getWriter()
.println("<p>keyname = " + datastore_key + " value = " + memcache_value + "</p>");
}
}
}
// display element of kind TaskData with key=keyname
else if (keyname != null && value == null) {
// first check in the cache
String memcache_value = (String) syncCache.get(keyname); // Read from cache.
// Get value from datastore
Key task_key = KeyFactory.createKey("TaskData", keyname);
try {
Entity tne = datastore.get(task_key);
if (memcache_value == null) {
resp.getWriter().println("<h2>Datastore</h2>");
} else {
resp.getWriter().println("<h2>Both</h2>");
}
} catch (EntityNotFoundException e) {
resp.getWriter().println("<h2>Neither</h2>");
}
}
// store element of kind TaskData with key=keyname and value=value
else if (keyname != null && value != null) {
Entity tne = new Entity("TaskData", keyname);
tne.setProperty("value", value);
tne.setProperty("date", new Date());
datastore.put(tne);
syncCache.put(keyname, value); // Populate cache.
resp.getWriter()
.println("<h2>Stored " + keyname + " and " + value + " in Datastore and Memcache</h2>");
} else {
resp.getWriter().println("<h2>You entered wrong query parameters</h2>");
}
/*
Entity tne = new Entity("TaskData", "Person");
alice.setProperty("gender", "female");
alice.setProperty("age", 20);
*/
resp.getWriter().println("</body></html>");
}