Question

我正在学习将EndPoints编程到Google-App-Engine，而且我直接与谷歌服务器合作，而不是本地。

在控制台谷歌中，我激活了API：Google Cloud Datastore API，Google Cloud Storage和Android Google Maps API v2。

我使用了我在下面描述的教程中找到的一个例子：

我有这个实体：

import com.googlecode.objectify.annotation.Entity;
import com.googlecode.objectify.annotation.Id;


@Entity
public class Quote {
    @Id
    Long id;
    String who;
    String what;


    public Quote() {}

    public Long getId() {
        return id;

    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getWho() {
        return who;
    }

    public void setWho(String who) {
        this.who = who;
    }

    public String getWhat() {
        return what;
    }

    public void setWhat(String what) {
        this.what = what;
    }
}

此EndPoint类：

import com.google.api.server.spi.config.Api;
import com.google.api.server.spi.config.ApiMethod;
import com.google.api.server.spi.config.ApiNamespace;
import com.google.api.server.spi.config.Nullable;
import com.google.api.server.spi.response.CollectionResponse;
import com.google.api.server.spi.response.ConflictException;
import com.google.api.server.spi.response.NotFoundException;
import com.google.appengine.api.datastore.Cursor;
import com.google.appengine.api.datastore.QueryResultIterator;
import com.googlecode.objectify.cmd.Query;

import static com.ringtheapp.parche.OfyService.ofy;

import java.util.ArrayList;
import java.util.List;

import javax.inject.Named;

@Api(name = "quoteEndpoint", version = "v1", namespace = @ApiNamespace(ownerDomain = "parche.mydomine.com", ownerName = "parche.mydomine.com", packagePath=""))
public class QuoteEndpoint {

// Make sure to add this endpoint to your web.xml file if this is a web application.

    public QuoteEndpoint() {

    }

    /**
     * Return a collection of quotes
     *
     * @param count The number of quotes
     * @return a list of Quotes
     */
    @ApiMethod(name = "listQuote")
    public CollectionResponse<Quote> listQuote(@Nullable @Named("cursor") String cursorString,
                                               @Nullable @Named("count") Integer count) {

        Query<Quote> query = ofy().load().type(Quote.class);
        if (count != null) query.limit(count);
        if (cursorString != null && cursorString != "") {
            query = query.startAt(Cursor.fromWebSafeString(cursorString));
        }

        List<Quote> records = new ArrayList<Quote>();
        QueryResultIterator<Quote> iterator = query.iterator();
        int num = 0;
        while (iterator.hasNext()) {
            records.add(iterator.next());
            if (count != null) {
                num++;
                if (num == count) break;
            }
        }

//Find the next cursor
        if (cursorString != null && cursorString != "") {
            Cursor cursor = iterator.getCursor();
            if (cursor != null) {
                cursorString = cursor.toWebSafeString();
            }
        }
        return CollectionResponse.<Quote>builder().setItems(records).setNextPageToken(cursorString).build();
    }

    /**
     * This inserts a new <code>Quote</code> object.
     * @param quote The object to be added.
     * @return The object to be added.
     */
    @ApiMethod(name = "insertQuote")
    public void insertQuote(Quote quote) throws ConflictException {
//If if is not null, then check if it exists. If yes, throw an Exception
//that it is already present
        if (quote.getId() != null) {
            if (findRecord(quote.getId()) != null) {
                throw new ConflictException("Object already exists");
            }
        }

//Since our @Id field is a Long, Objectify will generate a unique value for us
//when we use put
        ofy().save().entity(quote).now();

    }

    /**
     * This updates an existing <code>Quote</code> object.
     * @param quote The object to be added.
     * @return The object to be updated.
     */
    @ApiMethod(name = "updateQuote")
    public Quote updateQuote(Quote quote)throws NotFoundException {
        if (findRecord(quote.getId()) == null) {
            throw new NotFoundException("Quote Record does not exist");
        }
        ofy().save().entity(quote).now();
        return quote;
    }

    /**
     * This deletes an existing <code>Quote</code> object.
     * @param id The id of the object to be deleted.
     */
    @ApiMethod(name = "removeQuote")
    public void removeQuote(@Named("id") Long id) throws NotFoundException {
        Quote record = findRecord(id);
        if(record == null) {
            throw new NotFoundException("Quote Record does not exist");
        }
        ofy().delete().entity(record).now();
    }

    //Private method to retrieve a <code>Quote</code> record
    private Quote findRecord(Long id) {
        return ofy().load().type(Quote.class).id(id).now();
//or return ofy().load().type(Quote.class).filter("id",id).first.now();
    }

}

我有这个Ofy课程：

import com.googlecode.objectify.Objectify;
import com.googlecode.objectify.ObjectifyFactory;
import com.googlecode.objectify.ObjectifyService;

/**
 * Objectify service wrapper so we can statically register our persistence classes
 * More on Objectify here : https://code.google.com/p/objectify-appengine/
 *
 */
public class OfyService {

    static {
        ObjectifyService.register(Quote.class);
        ObjectifyService.register(Post.class);
    }

    public static Objectify ofy() {
        return ObjectifyService.ofy();
    }

    public static ObjectifyFactory factory() {
        return ObjectifyService.factory();
    }
}

当我转到API资源管理器时，使用这种地址格式＆＃34; https://apis-explorer.appspot.com/apis-explorer/?base=https://1-dot-myproyectname.appspot.com/_ah/api#p/＆＃34; ，它运行正常，它给了我5个实体，但是当我在计数字段中运行方法listQuote时，它将不会返回我的nextPageToken。

它给我这个计数= 2：

200 OK

- Show headers -

{
 "items": [
  {
   "id": "5629499534213120",
   "who": "Gladys",
   "what": "Es mi mama",
   "kind": "quoteEndpoint#resourcesItem"
  },
  {
   "id": "5639445604728832",
   "who": "Carlos",
   "what": "Posteando desde el programa",
   "kind": "quoteEndpoint#resourcesItem"
  }
 ],
 "kind": "quoteEndpoint#resources",
 "etag": "\"g5i3Q2SBLLa5w1FcUp586KnA8gM/c_cfE8SxmA5GujJh-tLzNMQGfrg\""
}

我缺少什么，如何获得nextPageToken？

Answer 1

只有在指定了上一个光标后才会返回光标。如果将null作为cursorString传递给端点方法，则不会返回新光标。使用下面的代码返回新的光标值。

//Find the next cursor
Cursor cursor = iterator.getCursor();
if (cursor != null) {
    cursorString = cursor.toWebSafeString();
}

运行Google API Explorer时，nextPageToken未显示在结果中

1 个答案: