实现从sql server存取二进制图片

转：http://www.cnblogs.com/jeffwongishandsome/archive/2009/08/27/1554440.html

1、存取图片
（1）、将图片文件转换为二进制并直接存进sql server

//UploadHelper.cs
     /// <summary>
    /// 将图片转化为长二进制
    /// </summary>
    /// <param name="photopath"></param>
    /// <returns></returns>
    public static Byte[] SetImgToByte(string imgPath)
    {
        FileStream file = new FileStream(imgPath, FileMode.Open, FileAccess.Read);
        Byte[] byteData = new Byte[file.Length];
        file.Read(byteData, , byteData.Length);
        file.Close();
        return byteData;
    }

    /// <summary>
    /// 将转换成二进制码的图片保存到数据库中
    /// </summary>
    public static bool SaveEmployeeImg2Db(Employee model, string path)
    {
        try
        {
            Byte[] imgBytes = SetImgToByte(path);
            model.Photo = imgBytes;
            bool flag=EmployeeService.SaveEmployeePhoto(model); //EmployeeService是公司内部的库调用，插入或者更新照片，这里不透露细节
            return flag;

        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

//将图片转换为字节流
FileStream fileStream = new FileStream(path + fileName, FileMode.Open, FileAccess.Read);
Byte[] byteData = new Byte[fileStream.Length];
fileStream.Read(byteData, , byteData.Length);
fileStream.Close();

a.Picture = byteData;//赋值
int result = _accessoryRepository.Update(a);//操作

//ADO.NET

SqlParameter p_Picture = new SqlParameter("@Picture", SqlDbType.Image);
p_Picture.Value = obj.Picture;

（2）、在网页中上传图片

/// <summary>
    /// 上传图片
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnUpload_Click(object sender, EventArgs e)
    {
        string serverPath = Server.MapPath("~/images/");
        if (this.fuPhoto.HasFile) //fuPhoto是fileupload控件
        {
            string fileName = this.fuPhoto.PostedFile.FileName;
            FileInfo fi = new FileInfo(fileName);
            string mimeType = this.fuPhoto.PostedFile.ContentType.ToLower();
            if (mimeType.IndexOf("image") < )
            {
                //("上传的照片格式不对");
            }
            else if(fi.Length > *  * )
            {
                //图片大于2M，重新处理
            }
            else
            {
                string saveFilePath = serverPath + DateTime.Now.ToString("yyyyMMddHHmmss") + fileName;
                try
                {
                    //先存图片到服务器
                    this.fuPhoto.PostedFile.SaveAs(saveFilePath);

                    //转成二进制
                    Employee model = new Employee(int.Parse(id)); //id是EmployeeId，这里是模拟字段
                    bool flag = UploadHelper.SaveEmployeeImg2Db(model, saveFilePath);
                }
                catch
                {
                    //("照片上传失败");
                }
                finally
                {
                    //最后删掉该图片
                    if (System.IO.File.Exists(saveFilePath))
                    {
                        System.IO.File.Delete(saveFilePath);
                    }
                }
            }
        }
        else
        {
            //("全选择要上传的照片");
        }
    }

（3）、从数据库取出照片（返回格式Image）

//UploadHelper.cs
     /// <summary>
    /// 将二进制转化为图片Image
    /// </summary>
    /// <param name="photopath"></param>
    /// <returns></returns>
    public static System.Drawing.Image GetImgFromByte(Employee model)
    {
        System.Drawing.Image img = null;
        try
        {
            Stream stream = new MemoryStream(model.Photo);
            img = System.Drawing.Image.FromStream(stream,false);
        }
        catch
        {
            img = null;
        }
        return img;
    }

上面的这个方法取出来之后，如果在winform下，直接给一个PictureBox的Image属性赋值就可以了。可是web下没有这么强大的控件，所以，就有了下面的步骤。

2、直接在网页中以流的形式显示图片
（1）、生成图片流页面（ImgHelper .aspx）
这个页面的设计页面什么也没有，类文件如下：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
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.Collections.Generic;
using System.IO;

/// <summary>
/// 图片辅助类
/// </summary>
public partial class ImgHelper : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!string.IsNullOrEmpty(Request["employeeId"])) //需要显示照片的页面传递的员工id
        {
            int employeeId = int.Parse(Request["employeeId"]);
            Employee model = //EmployeeService.GetEmployeeByCondition(new Employee(employeeId))[0] as Employee; //内部函数 查找一个员工 不透漏细节
            try
            {
                Byte[] byteImg = model.Photo;
                Stream stream = new MemoryStream(byteImg);
                System.Drawing.Bitmap img =(System.Drawing.Bitmap) System.Drawing.Bitmap.FromStream(stream, false); //转换成Bitmap
                Response.Buffer = false;
                Response.ContentType = "image/jpg";
                Response.AddHeader("Content-Disposition", "attachment;filename=photo.jpg");//照片名称叫photo.jpg
                Response.BinaryWrite(byteImg);//写入二进制流
                  Response.End();
            }
            catch
            {
                Response.End();
            }
        }
    }
}

（2）、显示照片的页面调用ImgHelper .aspx
在页面加载的时候，给图片控件赋值如下：

 this.imgPhoto.ImageUrl = "/ImgHelper.aspx?employeeId="+tmpEmployee.Id.ToString(); //imgPhoto是图片控件

/// <summary>
   /// 为图片生成缩略图
   /// </summary>
   /// <param name="phyPath">原图片的路径</param>
   /// <param name="width">缩略图宽</param>
   /// <param name="height">缩略图高</param>
   /// <returns></returns>
   public System.Drawing.Image GetThumbnail(System.Drawing.Image image, int width, int height)
   {
       Bitmap bmp = new Bitmap(width, height);
       //从Bitmap创建一个System.Drawing.Graphics
       System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
       //设置
       gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
       //下面这个也设成高质量
       gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
       //下面这个设成High
       gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
       //把原始图像绘制成上面所设置宽高的缩小图
       System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(, , width, height); 

       gr.DrawImage(image, rectDestination, , , image.Width, image.Height, GraphicsUnit.Pixel);
       return bmp;
   }