common类 ，得到16位MD5密码 ，分页相关， 上传方法，图片控制

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.OleDb;
using System.IO;

/// <summary>
/// Common 的摘要说明
/// </summary>
public class Common
{
    public Common()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

      /// <summary>
    /// 检测数据库是否存在指定条件的数据
    /// </summary>
    /// <param name="tableName">数据表名</param>
    /// <param name="strWhere">查询条件，需要加“where”如"where id = 7"</param>
    /// <returns>true:存在或false:不存在</returns>
    public static bool HasData(string tableName, string strWhere)
    {
        if (RecordsCount(tableName, strWhere) > 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }


    /// <summary>
    /// 得到16位MD5密码
    /// </summary>
    /// <param name="s"></param>
    /// <returns></returns>
    public static string GetMD5(string s)
    {
        string r = FormsAuthentication.HashPasswordForStoringInConfigFile(s, "MD5");
        r = r.Substring(8, 16);
        return r;
    }

    #region 分页相关

    /// <summary>
    /// 获取一页的数据记录。注意：此方法需要分页存储过程“GetPageData”的支持
    /// </summary>
    /// <param name="tableName">表名</param>
    /// <param name="tableID">主键</param>
    /// <param name="fieldName">需要返回的列，如果是多个，则以逗号间隔</param>
    /// <param name="pageSize">每页记录数</param>
    /// <param name="pageNum">当前页码</param>
    /// <param name="orderString">排序的条件(注意: 要加 order by，此参数可以不赋值)</param>
    /// <param name="whereString">查询条件 (注意: 要加 where，此参数可以不赋值)</param>
    public static DataSet PageData(string tableName, string tableID, string fieldName, int pageSize, int pageNum, string orderString, string whereString)
    {
        
        OleDbParameter[] values = new OleDbParameter[7] { 
            new OleDbParameter("@TableName", tableName), 
            new OleDbParameter("@TableID", tableID),
            new OleDbParameter("@FieldName", fieldName),
            new OleDbParameter("@PageSize", pageSize),
            new OleDbParameter("@PageNum", pageNum), 
            new OleDbParameter("@OrderString", orderString),
            new OleDbParameter("@WhereString", whereString)
        };


        return DataBase.ExecuteDataSet("GetPageData", values);
    }

    /// <summary>
    /// 返回符合条件的记录的页数
    /// </summary>
    /// <param name="recordCount">记录总数量</param>
    /// <param name="pageSize">页大小</param>
    public static int PagesCount(int recordCount, int pageSize)
    {
        int result = recordCount / pageSize;
        if (recordCount % pageSize > 0)
        {
            result++;
        }
        return result;
    }

    /// <summary>
    /// 返回符合条件的记录的数目
    /// </summary>
    /// <param name="tableName">数据表名</param>
    /// <param name="strWhere">查询条件，需要加“where”如"where id = 7"</param>
    public static int RecordsCount(string tableName, string strWhere)
    {
        return (int)DataBase.ExecuteScalar(string.Format("select count(*) from {0} {1}", tableName, strWhere));
    }
    #endregion  分页相关

    #region 上传方法
    /// <summary>
    /// 上传文件，返回上传的文件的名称
    /// </summary>
    /// <param name="FileUpload1">上传控件的名称</param>
    /// <param name="savePath">文件保存的绝对路径</param>
    public static string UploadPic(ref FileUpload FileUpload1, string savePath)
    {
        return UploadFile(ref FileUpload1, savePath, ".rar,.jpg,.gif,.png", 512);
    }

    /// <summary>
    /// 上传文件，返回上传的文件的名称
    /// </summary>
    /// <param name="FileUpload1">上传控件的名称</param>
    /// <param name="savePath">文件保存的绝对路径</param>
    /// <param name="fileExts">允许上传文件的扩展名，若是多个，则之间以逗号间隔</param>
    /// <param name="maxLength">文件的上限，单位为K。例如，限制最大为512K，则可直接将此参数赋值为“512”</param>
    public static string UploadFile(ref FileUpload FileUpload1, string savePath, string fileExts, int maxLength)
    {
        string fileExt, fileName, newFileName = "0", filePath = savePath;
        fileName = FileUpload1.FileName.Trim();
        if (fileName.Length > 0 && FileUpload1.PostedFile.ContentLength < maxLength * 1024)
        {
            int j = fileName.LastIndexOf('.');
            fileExt = fileName.Substring(j).ToLower();
            if (fileExts.IndexOf(fileExt) > -1)
            {
                Random r = new Random();
                int i = r.Next(0, 1000);
                newFileName = DateTime.Now.ToString("yyyyMMddHHmmss") + i.ToString() + fileExt;
                filePath += newFileName;
                FileUpload1.SaveAs(filePath);
            }
        }
        return newFileName;
    }
    #endregion 上传方法

    #region 图片控制

    static string defaultImgUrl = "~/NuoWanFile/default.jpg";//默认图片

    /// <summary>
    /// 设置默认图片：如果图片不存在则显示默认图片
    /// </summary>
    /// <param name="img">图片控件Id</param>
    public static void DisDefaultImage(ref Image img)
    {
        if (img != null)
        {
            Page page = new Page();
            if (!File.Exists(page.Server.MapPath(img.ImageUrl.Trim())))
            {
                img.ImageUrl = defaultImgUrl;
                img.Width = 70;
                img.Height = 70;
            }
        }
    }

    /// <summary>
    /// 限制图片宽度
    /// </summary>
    /// <param name="img">图片控件的ID</param>
    /// <param name="maxWidth">最大宽度</param>
    public static void SetImageWidth(ref Image img, int maxWidth)
    {
        if (img != null)
        {
            Page page = new Page();
            string path = page.Server.MapPath(img.ImageUrl);
            if (File.Exists(path))
            {
                System.Drawing.Image image = System.Drawing.Image.FromFile(path);//抽象目标图片为一个对象类型
                string str = image.Width.ToString();//得到图片的实际大小
                if (Convert.ToInt32(str) > maxWidth)
                {
                    img.Width = maxWidth;//设置图片控件大小
                }
            }
        }
    }
    #endregion 图片控制
}