/* Copyright c 2005-2012.
* Licensed under GNU LESSER General Public License, Version 3.
* http://www.gnu.org/licenses
*/
package org.beangle.model.query.limit;
import java.util.Iterator;
import org.beangle.commons.collection.page.Page;
import org.beangle.commons.collection.page.PageLimit;
import org.beangle.commons.collection.page.PageWapper;
import org.beangle.commons.collection.page.SinglePage;
import org.beangle.model.query.LimitQuery;
/**
* 基于查询的分页。<br>
* 当使用或导出大批量数据时，使用者仍以List的方式进行迭代。<br>
* 该实现则是内部采用分页方式。
*
* @author chaostone
*/
public abstract class AbstractQueryPage<T> extends PageWapper<T> {
protected int pageNo = 0;
protected int maxPageNo = 0;
protected LimitQuery<T> query;
abstract public Page<T> moveTo(int pageNo);
public AbstractQueryPage() {
super();
}
public AbstractQueryPage(LimitQuery<T> query) {
this.query = query;
if (null != query) {
if (null == query.getLimit()) {
query.limit(new PageLimit(pageNo, Page.DEFAULT_PAGE_SIZE));
} else {
pageNo = query.getLimit().getPageNo() - 1;
}
}
}
/**
* 按照单个分页数据设置.
*
* @param page
*/
protected void setPageData(SinglePage<T> page) {
setPage(page);
this.pageNo = page.getPageNo();
this.maxPageNo = page.getMaxPageNo();
}
public Page<T> next() {
return moveTo(pageNo + 1);
}
public Page<T> previous() {
return moveTo(pageNo - 1);
}
public boolean hasNext() {
return maxPageNo > pageNo;
}
public boolean hasPrevious() {
return pageNo > 1;
}
public int getFirstPageNo() {
return 1;
}
public int getMaxPageNo() {
return maxPageNo;
}
public int getNextPageNo() {
return getPage().getNextPageNo();
}
public int getPageNo() {
return pageNo;
}
public int getPageSize() {
return query.getLimit().getPageSize();
}
public int getPreviousPageNo() {
return getPage().getPreviousPageNo();
}
public int getTotal() {
return getPage().getTotal();
}
public Iterator<T> iterator() {
return new PageIterator<T>(this);
}
}
class PageIterator<T> implements Iterator<T> {
private final AbstractQueryPage<T> queryPage;
private int dataIndex;
public PageIterator(AbstractQueryPage<T> queryPage) {
this.queryPage = queryPage;
this.dataIndex = 0;
}
public boolean hasNext() {
return (dataIndex < queryPage.getPage().getItems().size()) || (queryPage.hasNext());
}
public T next() {
if (dataIndex < queryPage.getPage().size()) {
return queryPage.getPage().getItems().get(dataIndex++);
} else {
queryPage.next();
dataIndex = 0;
return queryPage.getPage().getItems().get(dataIndex++);
}
}
public void remove() {
}
}