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/*
* Copyright (c) 2018 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you
* may not use this file except in compliance with the License. You may
* obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.android.vts.util;
import com.google.appengine.api.datastore.Cursor;
import com.google.appengine.api.datastore.QueryResultIterator;
import com.googlecode.objectify.cmd.Query;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/** Helper class for pagination. */
public class Pagination<T> implements Iterable<T> {
/** the default page size */
public static final int DEFAULT_PAGE_SIZE = 10;
/** the default page window size */
private static final int DEFAULT_PAGE_WINDOW = 10;
/** the current page */
private int page;
/** the page window size */
private int pageSize = DEFAULT_PAGE_SIZE;
/** the total number of found entities */
private int totalCount;
/** the cursor string token where to start */
private String nextPageCountToken = "";
/** the maximum number of pages */
private int maxPages;
/** the list of object on the page */
private List<T> list = new ArrayList<>();
public Pagination(List<T> list, int page, int pageSize, int totalCount) {
this.list = list;
this.page = page;
this.pageSize = pageSize;
this.totalCount = totalCount;
}
public Pagination(Query<T> query, int page, int pageSize, String nextPageToken) {
this.page = page;
this.pageSize = pageSize;
int limitValue = pageSize * DEFAULT_PAGE_WINDOW + pageSize;
query = query.limit(limitValue);
if (nextPageToken.equals("")) {
this.totalCount = query.count();
} else {
query = query.startAt(Cursor.fromWebSafeString(nextPageToken));
this.totalCount = query.count();
}
this.maxPages = this.totalCount / this.pageSize + (this.totalCount % this.pageSize == 0 ? 0 : 1);
QueryResultIterator<T> resultIterator = query.iterator();
int iteratorIndex = 1;
int startIndex = page / pageSize * pageSize;
while (resultIterator.hasNext()) {
if (startIndex <= iteratorIndex && iteratorIndex < startIndex + this.pageSize)
this.list.add(resultIterator.next());
else
resultIterator.next();
iteratorIndex++;
}
this.nextPageCountToken = resultIterator.getCursor().toWebSafeString();
}
public Iterator<T> iterator() {
return list.iterator();
}
/**
* Gets the total number of objects.
*
* @return the total number of objects as an int
*/
public int getTotalCount() {
return totalCount;
}
/**
* Gets the number of page window.
*
* @return the number of page window as an int
*/
public int getPageSize() {
return pageSize;
}
/**
* Gets the maximum number of pages.
*
* @return the maximum number of pages as an int
*/
public int getMaxPages() {
return this.maxPages;
}
/**
* Gets the page.
*
* @return the page as an int
*/
public int getPage() {
return page;
}
/**
* Gets the minimum page in the window.
*
* @return the page number
*/
public int getMinPageRange() {
if (this.getPage() < DEFAULT_PAGE_WINDOW) {
return 1;
} else {
return this.getPage() / DEFAULT_PAGE_WINDOW * DEFAULT_PAGE_WINDOW;
}
}
/**
* Gets the maximum page in the window.
*
* @return the page number
*/
public int getMaxPageRange() {
if (this.getPage() < DEFAULT_PAGE_WINDOW) {
return DEFAULT_PAGE_WINDOW;
} else {
if (this.getMaxPages() > DEFAULT_PAGE_WINDOW) {
return this.getPage() / DEFAULT_PAGE_WINDOW * DEFAULT_PAGE_WINDOW + this.pageSize;
} else {
return this.getMinPageRange() + this.getMaxPages();
}
}
}
/**
* Gets the subset of the list for the current page.
*
* @return a List
*/
public List<T> getList() {
return this.list;
}
/**
* Gets the cursor token for the next page starting point.
*
* @return a string of cursor of next starting point
*/
public String getNextPageCountToken() {
return this.nextPageCountToken;
}
}
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