package util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

/**
 * @author Hongyu
 * 
 * @param <T>
 */
public class Pagination<T> {
	// 当前页
	private Integer nowPage;
	// 页面要显示信息条数
	private Integer pageSize;
	// 根据页面显示的条数计算总页数
	private Integer countPage;
	// 根据传入的查询数据库中的信息的条数
	private Integer total;
	// 向数据库查询时的开始的下标
	private Integer startIndex;
	// 向数据库查询时的查询条数
	private Integer endIndex;


	// 将查询到的数据存放到这里
	private List<T> rows;

	public Pagination(Integer nowPage, Integer pageSize, String tableName) {
		// 赋值
		this.nowPage = nowPage;
		this.pageSize = pageSize;

		// 判断当前页是否合法
		if (this.nowPage < 1) {
			this.nowPage = 1;
		}

		// 向数据库发送查询,查询出指定表格的数据的总数
		this.total = this.getCountSize(tableName);
		// 计算总页数
		this.countPage = this.total % this.pageSize == 0 ? this.total
				/ this.pageSize : this.total / this.pageSize + 1;

		if (this.nowPage > this.countPage) {
			this.nowPage = this.countPage;
		}

		//System.out.println("pagenation中的nowPage==========" + this.nowPage);
		// 计算出开始的记录下标,和每页要显示的条数

		if (this.nowPage == 0) {
			this.startIndex = this.nowPage * this.pageSize;
			this.endIndex = this.pageSize;
		} else {
			this.startIndex = (this.nowPage - 1) * this.pageSize;
			this.endIndex = this.pageSize;
		}

		/*System.out.println(this.startIndex + "======pagenation中的开始和结束========"
				+ this.endIndex+"====================总页数"+countPage);
*/
	}

	// 根据提供的表名向数据库发送请求,计算指定数据表中的数据总条数
	public Integer getCountSize(String tableName) {
		int countRecord = 0;
		String sql = "select count(*) as c from " + tableName;
		Connection conn = JdbcUtil.getConn();
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try {
			pstmt = conn.prepareStatement(sql);
			rs = pstmt.executeQuery();
			if (rs.next()) {
				countRecord = rs.getInt("c");
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			JdbcUtil.release(rs, pstmt);
		}
		return countRecord;
	}

	public List<T> getRows() {
		return rows;
	}

	public void setRows(List<T> rows) {
		this.rows = rows;
	}

	public Integer getStartIndex() {
		return startIndex;
	}

	public Integer getEndIndex() {
		return endIndex;
	}

	public Integer getTotal() {
		return total;
	}
	


}