Java tutorial
/* * Copyright 2002-2010 the original author or authors. * * 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 org.jdal.dao; import java.io.Serializable; import java.util.ArrayList; import java.util.List; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * A Page of Objects as result of query on PaginableDataSource * Holds results for a page and info of Page definition page size and order. * * @author Jose Luis Martin - (jlm@joseluismartin.info) */ @SuppressWarnings("unchecked") public class Page<T> implements Paginator, Cloneable, Serializable { private static final Log log = LogFactory.getLog(Page.class); public static enum Order { ASC, DESC }; /** List of results */ private List<T> data = new ArrayList<T>(); /** Result count, Not the page size, the count of all result if not paginated */ private int count; /** the page size */ private int pageSize; /** sort by this property name */ private String sortName; /** sort order */ private Order order; /** a Object used as filter */ private Object filter; /** page number */ private int page = 1; /** PageableDataSource that loads the page */ private transient PageableDataSource<?> pageableDataSource; /** Paginator Listeners */ private ArrayList<PaginatorListener> listeners = new ArrayList<PaginatorListener>(); public Page(int pageSize, int page, String sortName, Order order) { this.pageSize = pageSize; if (page > 0) this.page = page; this.sortName = sortName; this.order = order; } public Page(int pageSize, int page, String sortName) { this(pageSize, page, sortName, Order.ASC); } public Page(int pageSize, int page) { this(pageSize, page, null); } public Page(int pageSize) { this(pageSize, 1); } public Page() { this(10); } /** * @return list of data objects */ public List<T> getData() { return data; } /** * @return the count */ public int getCount() { return count; } /** * @param count the count to set */ public void setCount(int count) { this.count = count; } /** * @return the sortName */ public String getSortName() { return sortName; } /** * @param sortName the sortName to set */ public void setSortName(String sortName) { this.sortName = sortName; } /** * @return the order */ public Order getOrder() { return order; } /** * @param order the order to set */ public void setOrder(Order order) { this.order = order; } /** * @param data the data to set */ public void setData(List<T> data) { this.data = data; } public void setOrderAsc() { setOrder(Order.ASC); } public void setOrderDesc() { setOrder(Order.DESC); } /** * @return the filter */ public Object getFilter() { return filter; } /** * @param filter the filter to set */ public void setFilter(Object filter) { this.filter = filter; } public Page<T> clone() { try { return (Page<T>) super.clone(); } catch (CloneNotSupportedException e) { log.error(e); return null; } } /** * @return the pageableDataSource */ public PageableDataSource<?> getPageableDataSource() { return pageableDataSource; } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#hasNext() */ public boolean hasNext() { return page < getTotalPages(); } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#hasPage(int) */ public boolean hasPage(int indexPage) { return indexPage <= getTotalPages() && indexPage > 0; } /** * {@inheritDoc} */ public boolean hasPrevious() { return page > 1; } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#setPage(int) */ public void setPage(int indexPage) { if (indexPage > 0) { page = indexPage; load(); firePageChangedEvent(); } else { log.warn("Try to set a page < 1"); } } /** * {@inheritDoc} */ public int getStartIndex() { return (page - 1) * pageSize; } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#getTotalPages() */ public int getTotalPages() { if (pageSize > 0) return (int) Math.ceil(count / pageSize) + (count % pageSize == 0 ? 0 : 1); return 1; } /** * {@inheritDoc} */ public void addPaginatorListener(PaginatorListener listener) { if (!listeners.contains(listener)) listeners.add(listener); } /** * {@inheritDoc} */ public void removePaginatorListener(PaginatorListener listener) { listeners.remove(listener); } /** * @return the pageSize */ public int getPageSize() { return pageSize; } /** * @param pageSize the pageSize to set */ public void setPageSize(int pageSize) { if (pageSize > 0) { // need to recalculate current page page = (int) Math.ceil(getStartIndex() / pageSize) + 1; this.pageSize = pageSize; load(); firePageChangedEvent(); } } /** * @return the page */ public int getPage() { return page; } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#firstPage() */ public void firstPage() { setPage(1); } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#lastPage() */ public void lastPage() { setPage(getTotalPages()); } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#nextPage() */ public void nextPage() { setPage(page + 1); } /** * {@inheritDoc} * @see org.jdal.dao.Paginator#previousPage() */ public void previousPage() { setPage(page - 1); } /** * Notify Listener that current page changed */ private void firePageChangedEvent() { for (PaginatorListener listener : listeners) { listener.pageChanged(new PageChangedEvent(this, page, getStartIndex(), getTotalPages(), pageSize)); } } public void load() { if (pageableDataSource != null) { Page<T> newPage = pageableDataSource.getPage(this); this.data = newPage.data; } } /** * @param pageableDataSource the pageableDataSource to set */ public void setPageableDataSource(PageableDataSource<?> pageableDataSource) { this.pageableDataSource = pageableDataSource; } }