pageinfoimpl.java

分页技术

package common.songbing.page;

import java.util.List;

public class PageInfoImpl implements PageInfo {
	private List pageData;  //分页内容列表
	private int pageCount;  //分页总数
	private int pageSize; //当前页的记录数
	private long totalRecords; //总记录数
	private int start; //当前页的起始索引(记录在结果集中的索引位置）
	private int currentNo; //当前页码
	
	public PageInfoImpl(List pageData, long totalRecords, int pageSize, int pageNo) {
		this.pageData = pageData;
		this.totalRecords = totalRecords;
		this.pageSize = pageSize;
		this.currentNo = pageNo;
		
		//计算其它值
		pageCount = (int)((totalRecords + pageSize - 1) / pageSize);
		if(totalRecords <= 0) {
			pageCount = 0;
		}
		
		if(currentNo == pageCount) { //如果当前页是最后一页,则当前页的记录数有可能少于每页显示的最大记录数
			this.pageSize = (int)(totalRecords - ((pageCount - 1) * pageSize));
		}
		
		start = (pageNo - 1) * pageSize;
	}

	public int getCurrentPageNo() {
		return currentNo;
	}

	public long getEndIndex() {
		return start + pageSize - 1;
	}

	public int getPageCount() {
		return pageCount;
	}

	public List getPageData() {
		return pageData;
	}

	public int getPageSize() {
		return pageSize;
	}

	public long getTotalRecords() {
		return totalRecords;
	}

	public long getStartIndex() {
		return start;
	}

	public int getStartOfNextPage() {
		int pageNo = currentNo + 1;
		if(pageNo > pageCount) {
			pageNo = pageCount;
		}
		return this.getStartOfPage(pageNo);
	}

	public int getStartOfPage(int pageNo) {
		int startIndex = (pageNo - 1) * pageSize + 1;
		if(startIndex < 1) {
			startIndex = 1;
		}
		return startIndex;
	}

	public int getStartOfPreviousPage() {
		int pageNo = currentNo - 1;
		if(pageNo < 1) {
			pageNo = 1;
		}
		return this.getStartOfPage(pageNo);
	}

	public boolean isNextPageEnable() {
		return currentNo < pageCount;
	}

	public boolean isPreviousPageEnable() {
		return currentNo > 1;
	}
}