pagedao.java

JSP+Servlet+JavaBean+标签文件写的分页标签！

package page;

import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Vector;

/**
 * <p>Title: 分页标签</p>
 *
 * <p>Description: 数据访问类</p>
 *
 * <p>Copyright: Copyright (c) 2007</p>
 *
 * <p>Company: ACCP</p>
 *
 * @author HuWenJun
 * @version 1.0
 */

public class PageDAO {
    private Connection con = null;
    private Statement stmt = null;
    private ResultSet rs = null;
    private String sql = "";
    private static PageDAO me = new PageDAO();

    private PageDAO() {
    }

    public static PageDAO newInstance() {
        return me;
    }

    /**
     * 获得指定页要显示的数据
     * @param tableName 表名
     * @param column 列名
     * @param primaryKey 主键字段
     * @param rowsPerPage 每页显示多少行
     * @param curPage 当前是第几页
     * @param columnCount 列数
     * @return Vector 数据
     */
    public Vector getData(String tableName, String columnNames,
                          String primaryKey,
                          int rowsPerPage, int curPage) {
        Vector data = new Vector();
        try {
            DataBaseConn cBean = DataBaseConn.newInstance();
            con = cBean.getConnDB();
            stmt = con.createStatement();
            sql = "select top " + rowsPerPage + " * from " +
                  tableName + " where " + primaryKey +
                  " not in (select top " + (curPage - 1) * rowsPerPage +
                  " " + primaryKey + " from " + tableName +
                  " order by " + primaryKey + " desc) order by " +
                  primaryKey + " desc";
            rs = stmt.executeQuery(sql);
            String[] columns = columnNames.split(",");
            while (rs.next()) {
                //根据列数动态创建数组
                Object[] obj = new Object[columns.length];
                for (int j = 0; j < columns.length; j++) {
                    //从结果集中取相应字段的值存入数组
                    obj[j] = rs.getString(columns[j]);
                }
                data.add(obj);
            }
            rs.close();
            stmt.close();
            con.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return data;
    }

    /**
     * 获得总记录数
     * @param tableName 表名
     * @return int 记录数
     */
    public int getAvailableCount(String tableName) {
        int count = 0;
        try {
            DataBaseConn cBean = DataBaseConn.newInstance();
            con = cBean.getConnDB();
            stmt = con.createStatement();
            String strSql = "select count(*) as maxRow from " + tableName;
            rs = stmt.executeQuery(strSql);
            if (rs.next()) {
                count = rs.getInt("maxRow");
            }
            rs.close();
            stmt.close();
            con.close();
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
        return count;
    }
}