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(c#)实现从sql server存取二进制图片

发布时间:2009年09月04日点击数: 未知

有一个员工表Employee,需要保存员工照片(Photo)到数据库(sql server)上。员工照片对应的字段是varbinary(max),也就是要存成二进制文件类型(这和以前讨巧地存图片文件路径就不相同了),默认可以为空。下面说说主要实现思路:
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
     ///
    /// 将图片转化为长二进制
    ///
    /// "photopath">
    ///
    public static Byte[] SetImgToByte(string imgPath)
    {
        FileStream file = new FileStream(imgPath, FileMode.Open, FileAccess.Read);
        Byte[] byteData = new Byte[file.Length];
        file.Read(byteData, 0, byteData.Length);
        file.Close();
        return byteData;
    }


    ///
    /// 将转换成二进制码的图片保存到数据库中
    ///
    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;
        }

    }

 

(2)、在网页中上传图片

///
    /// 上传图片
    ///
    /// "sender">
    /// "e">
    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") < 0)
            {
                //("上传的照片格式不对");
            }

            else if(fi.Length > 2* 1024 * 1024)
            {
                //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
     ///
    /// 将二进制转化为图片Image
    ///
    /// "photopath">
    ///
    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;


///
/// 图片辅助类
///
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
 

总体来说,一存一取,对于winform是很方便的,但是对于webform,我们需要稍微有一个转化的思路。如果有牛人写出像winform下那种直接绑定Image对象的控件更好了。上面代码测试通过,希望对你有帮助。
 

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