我已经尝试了一千件事。截至目前，我查询任何内容的唯一方法是获取整个列表并以这种方式查看！这需要很多时间。我如何在谷歌应用程序引擎中查询某些内容，例如仅提取具有 > 100 票的实体。
我关注井字游戏示例https://github.com/GoogleCloudPlatform/appengine-endpoints-tictactoe-java和https://developers.google.com/eclipse/docs/endpoints-addentities 在示例中我刚刚切换报价注释。
这是我当前的代码，例如关于我如何获取实体这是一个异步任务及其加载每个需要很长时间的
protected CollectionResponseQuotes doInBackground(Context... contexts) {
Quotesendpoint.Builder endpointBuilder = new Quotesendpoint.Builder(
AndroidHttp.newCompatibleTransport(),
new JacksonFactory(),
new HttpRequestInitializer() {
public void initialize(HttpRequest httpRequest) { }
});
Quotesendpoint endpoint = CloudEndpointUtils.updateBuilder(
endpointBuilder).build();
try {
quotes = endpoint.listquotes().execute();
for (Quotes quote : quotes.getItems()) {
if (quote.getVotes() > 3) {
quoteList.add(quote);
}
}
这是我在创建端点时 Google 在应用引擎中为我生成的代码。看起来它会以某种方式查询，但我无法弄清楚。它们是两个不同的项目。
@Api(name = "quotesendpoint", namespace = @ApiNamespace(ownerDomain = "projectquotes.com", ownerName = "projectquotes.com", packagePath = ""))
public class quotesEndpoint {
/**
* This method lists all the entities inserted in datastore.
* It uses HTTP GET method and paging support.
*
* @return A CollectionResponse class containing the list of all entities
* persisted and a cursor to the next page.
*/
@SuppressWarnings({ "unchecked", "unused" })
@ApiMethod(name = "listquotes")
public CollectionResponse<quotes> listquotes(
@Nullable @Named("cursor") String cursorString,
@Nullable @Named("limit") Integer limit) {
EntityManager mgr = null;
Cursor cursor = null;
List<quotes> execute = null;
try {
mgr = getEntityManager();
Query query = mgr.createQuery("select from quotes as quotes");
if (cursorString != null && cursorString != "") {
cursor = Cursor.fromWebSafeString(cursorString);
query.setHint(JPACursorHelper.CURSOR_HINT, cursor);
}
if (limit != null) {
query.setFirstResult(0);
query.setMaxResults(limit);
}
execute = (List<quotes>) query.getResultList();
cursor = JPACursorHelper.getCursor(execute);
if (cursor != null)
cursorString = cursor.toWebSafeString();
// Tight loop for fetching all entities from datastore and accomodate
// for lazy fetch.
for (quotes obj : execute)
;
} finally {
mgr.close();
}
return CollectionResponse.<quotes> builder().setItems(execute)
.setNextPageToken(cursorString).build();
}
/**
* This method gets the entity having primary key id. It uses HTTP GET method.
*
* @param id the primary key of the java bean.
* @return The entity with primary key id.
*/
@ApiMethod(name = "getquotes")
public quotes getquotes(@Named("id") String id) {
EntityManager mgr = getEntityManager();
quotes quotes = null;
try {
quotes = mgr.find(quotes.class, id);
} finally {
mgr.close();
}
return quotes;
}
尝试使用用户光标，但现在确定它是如何工作的。我试过了
Cursor cursor = db.rawQuery("select * from Votes WHERE Votes >" + 250 , null);
quotes = endpoint.listquotes().setCursor(cursor).execute();