org.pageseeder.flint.lucene.query.SearchPaging Maven / Gradle / Ivy
/*
* Copyright 2015 Allette Systems (Australia)
* http://www.allette.com.au
*
* 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.pageseeder.flint.lucene.query;
/**
* This class allows for a better control of search results by specifying paging information for the
* index tools to use.
*
* Pages start at 1.
*
*
Note: This has nothing to do with memory management.
*
* @author Christophe Lauret (Weborganic)
* @version 10 February 2012
*/
public final class SearchPaging {
/**
* The default maximum number of hits per page.
*/
public static final int DEFAULT_PAGE = 1;
/**
* The default maximum number of hits per page.
*/
public static final int DEFAULT_HITS_PER_PAGE = 20;
/**
* The requested page of the search results.
*/
private int _page = DEFAULT_PAGE;
/**
* The number of hits per page, default is 20.
*/
private int _hitsPerPage = DEFAULT_HITS_PER_PAGE;
/**
* Creates a new paging configuration using the default values.
*/
public SearchPaging() {
}
/**
* Creates a new paging configuration using the specified values.
*
* @param page The page requested.
* @param hitsPerPage The maximum number of results per page.
*/
public SearchPaging(int page, int hitsPerPage) {
this._page = page;
this._hitsPerPage = hitsPerPage;
}
/**
* Returns the number of hits per page for the searches.
*
* @return The number of hits per page for the searches.
*/
public int getHitsPerPage() {
return this._hitsPerPage;
}
/**
* Sets the number of hits per page for the searches.
*
*
A negative value in indicates no limit.
*
* @param hitsPerPage The number of hits per page for the searches.
*/
public void setHitsPerPage(int hitsPerPage) {
this._hitsPerPage = hitsPerPage;
}
/**
* Returns the requested page number.
*
* @return The requested page number.
*/
public int getPage() {
return this._page;
}
/**
* Sets the page number.
*
* @param page The page number.
*
* @throws IllegalArgumentException if the page is less than 1.
*/
public void setPage(int page) {
if (page < 1) throw new IllegalArgumentException("Pages must be positive natural integers");
this._page = page;
}
// Methods providing common function for a result set
// ----------------------------------------------------------------------------------------------
/**
* Returns the first hit based on the total number of hits.
*
*
If hits per page is positive, it is the result of :
*
* HITS_PER_PAGE x (PAGE - 1) + 1
*
* Otherwise, this method always returns 1;
*
* @return the first hit based on the total number of hits (inclusive)
*/
public int getFirstHit() {
if (this._hitsPerPage <= 0) return 1;
return this._hitsPerPage * (this._page - 1) + 1;
}
/**
* Returns the last hit for the current page in the results based on the total number hits.
*
*
If hits per page is positive, it is the result of :
*
* MIN( HITS_PER_PAGE x PAGE - 1, TOTAL_HITS)
*
* Otherwise, this method always returns 1;
*
* @param totalHits The total number of hits.
*
* @return the last hit based on the total number of hits (inclusive).
*/
public int getLastHit(int totalHits) {
if (this._hitsPerPage <= 0) return totalHits;
return Math.min(totalHits, this._hitsPerPage * this._page);
}
/**
* Returns the number of pages in the results based on the total number hits.
*
*
If hits per page is positive, it is the result of :
*
* ((TOTAL_HITS - 1) / HITS_PER_PAGE) + 1
*
* Otherwise, this method always returns 1;
*
* @param totalHits The total number of hits.
*
* @return the last hit based on the total number of hits (inclusive).
*/
public int getPageCount(int totalHits) {
if (this._hitsPerPage <= 0) return 1;
return ((totalHits - 1) / this._hitsPerPage) + 1;
}
}