// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
package jodd.joy.page;
import java.util.List;
/**
* Holds information about single page of results.
* Item indexes are zero-based and page numbers are one-based.
*/
public class PageData<T> {
protected final int pageSize;
/**
* Returns page size, i.e. number of items per page.
*/
public int getPageSize() {
return pageSize;
}
protected final int firstIndex;
/**
* Returns index of the first item on this page.
*/
public int getFirstIndex() {
return firstIndex;
}
protected final int lastIndex;
/**
* Returns index of last item of page.
* On every page but last, last index equals to first index plus page size.
*/
public int getLastIndex() {
return lastIndex;
}
protected final List<T> items;
/**
* Returns the list of items on this page.
*/
public List<T> getItems() {
return items;
}
protected final int totalItems;
/**
* Returns total number of items.
*/
public int getTotalItems() {
return this.totalItems;
}
protected final int totalPages;
/**
* Returns total number of pages.
*/
public int getTotalPages() {
return totalPages;
}
protected int currentPage;
/**
* Returns current page number.
*/
public int getCurrentPage() {
return currentPage;
}
protected final int pageItemsCount;
/**
* Returns the number of shown items per page.
* Note that this value is calculated.
*/
public int getPageItemsCount() {
return pageItemsCount;
}
// ---------------------------------------------------------------- ctors
public PageData() {
this(1, 0, PageRequest.defaultPageSize, null);
}
public PageData(int page, int size) {
this(page, size, PageRequest.defaultPageSize, null);
}
public PageData(int page, int size, int pageSize) {
this(page, size, pageSize, null);
}
public PageData(PageRequest req, int size, List<T> items) {
this(req.getPage(), size, req.getSize(), items);
}
/**
* Main constructor.
* @param page current page
* @param size total number of items
* @param pageSize number of items per page
* @param items list of fetched items
*/
public PageData(int page, int size, int pageSize, List<T> items) {
if (pageSize <= 0) {
pageSize = PageRequest.defaultPageSize;
}
this.pageSize = pageSize;
this.totalItems = size;
this.items = items;
this.totalPages = (totalItems % pageSize == 0) ? totalItems / pageSize : totalItems / pageSize + 1;
if (page < 1) {
page = 1;
}
if (page > totalPages) {
page = totalPages;
}
this.currentPage = page;
this.firstIndex = calcFirstItemIndexOfPage(page, pageSize, size);
int last = isLastPage() ? totalItems - 1: firstIndex + pageSize - 1;
int itemsPerPage = last - firstIndex + 1;
if (last < 0) {
last = 0;
itemsPerPage = 0;
}
this.lastIndex = last;
this.pageItemsCount = itemsPerPage;
}
// ---------------------------------------------------------------- checks
/**
* Returns <code>true</code> if there is a next page, i.e. we are not at the last page.
*/
public boolean hasNextPage() {
return currentPage < totalPages - 1;
}
/**
* Returns <code>true</code> if we are on the last page.
*/
public boolean isLastPage() {
return currentPage == totalPages;
}
/**
* Returns <code>true</code> if there is a previous page, i.e. we are not at the first page.
*/
public boolean hasPreviousPage() {
return currentPage > 1;
}
/**
* Returns <code>true</code> id we are on the first page.
*/
public boolean isFirstPage() {
return currentPage == 1 || currentPage == 0;
}
/**
* Convenient report method that can be used as JSON array.
*/
@Override
public String toString() {
return new StringBuilder().append('[').append(currentPage).append(',')
.append(totalPages).append(',').append(totalItems).append(',')
.append(firstIndex).append(',').append(lastIndex).append(',')
.append(pageSize).append(']').toString();
}
// ---------------------------------------------------------------- utilities
/**
* Calculates page number that contains some item.
*/
public static int calcPageOfItem(int itemIndex, int pageSize) {
return itemIndex / pageSize + 1;
}
/**
* Calculates the first item index of requested page.
*/
public static int calcFirstItemIndexOfPage(int page, int pageSize, int total) {
if (total == 0) {
return 0;
}
if (page < 1) {
page = 1;
}
int first = (page - 1) * pageSize;
if (first >= total) {
first = ((total - 1) / pageSize) * pageSize; // first item on the last page
}
return first;
}
/**
* Calculates first item index of the page.
*/
public static int calcFirstItemIndexOfPage(PageRequest pageRequest, int total) {
return calcFirstItemIndexOfPage(pageRequest.getPage(), pageRequest.getSize(), total);
}
}