asp.net 上传图片生成缩略图效果
下面这个.net操作类是一款图片操作类，他的原理是很把图片上传到远程服务器，然后再根据用户设置生成小图或其它操作，有需要的朋友可以参考一下。
public class imghelp
{
//public static string gif = "image/gif";
//public static string jpg = "image/pjpeg";
//public static string png = "image/x-png";
page pag = new page();
string[] imgtype = { "image/gif", "image/pjpeg", "image/x-png" };
public static string thisyear = datetime.now.year.tostring();
public static string thismonth = datetime.now.month.tostring();
public static string thisday = datetime.now.day.tostring();
string strdate = thisyear + thismonth + thisday + datetime.now.hour.tostring() + datetime.now.second.tostring() + datetime.now.minute.tostring() + datetime.now.millisecond.tostring();/// <summary>
/// 保存上传的文件返回true为保存成功massage为文件路径,返回false为保存失败massage错误信息
/// </summary>
/// <param name="producfile"></param>
/// <param name="size">允许上传的最大值(以字节为单位)</param>
/// <param name="addurl">存储路径</param>
/// <param name="massage">存储信息</param>
/// <returns></returns>
public bool upimg(fileupload producfile, int size, string addurl, out string massage)
{
string mag;
bool su = false;
int i = throwimg(producfile, size, out mag);
if (i == 1)
{
//新文件名
string newfilename = strdate + producfile.filename.replace("~", "").replace("|", "").replace("&", "");
string url = addurl;
string pddurl = pag.server.mappath(url);
try
{
if (!directory.exists(pddurl))
{
directory.createdirectory(pddurl);
}
if (file.exists(pag.server.mappath(url + newfilename)) == false)
{
producfile.saveas(pag.server.mappath(url + newfilename));
massage = url + newfilename;
su = true;
}
else
{
massage = "上传文件名已经存在,请重新上传!";
}
}
catch
{
massage = "文件上传时程序出现异常,请重新上传!";
}
}
else
{
massage = mag;
}
return su;}
/// <summary>
/// 上传图片关生成 缩略图
/// </summary>
/// <param name="producfile">控件</param>
/// <param name="size">允许上传的最大值(以字节为单位)</param>
/// <param name="addurl">存储路径</param>
/// <param name="frontname">保存文件前缀名集合</param>
/// <param name="imgwid">,宽度集合</param>
/// <param name="imghid">高度集合</param>
/// <param name="massage">返回上传信息</param>
/// <returns></returns>
public bool upimgandbreviary(fileupload producfile, int size, string addurl,string[] frontname,int[] imgwid,int[] imghid,out string massage)
{
string mag;
bool key = false;
int i = throwimg(producfile, size, out mag);
if (i != 1)
{
massage = mag;
key = false;
}
else if (frontname.length <= 0 || frontname.length != imgwid.length || frontname.length != imghid.length)
{
massage = "缩略图信息不相符";
key = false;
}
else
{
//新文件名
string newfilename = "primary_" + strdate + producfile.filename.replace("primary_", "");
//存储路径
string url = addurl + thisyear + "/" + thismonth + "/" + thisday;
//转为服务器的绝对路径
string pddurl = pag.server.mappath(url);try
{
//判断路径目录是否存在
if (!directory.exists(pddurl))
{
//创建目录
directory.createdirectory(pddurl);
if (file.exists(pag.server.mappath(url + "/" + newfilename)) == false)
{
//保存文件
producfile.saveas(pag.server.mappath(url + "/" + newfilename));
//返回文件地址
massage = url + "/" + newfilename;//生成缩略图
for (int j = 0; j < frontname.length; j++)
{
breviaryimg(massage, massage.replace("primary_", frontname[j]), imgwid[j], imghid[j]);
}
key = true;//生成两张缩略图,保存名是在原图名前加了一个middle_,small_。
//newwidth1 = 200;
//newheight1 = 200;
//newwidth2 = 60;
//newheight2 = 60;
//breviaryimg(massage, massage.replace("primary_", "middle_"), newwidth1, newheight1);
//breviaryimg(massage, massage.replace("primary_", "small_"), newwidth2, newheight2);}
else
{
massage = "上传文件重名,请重新上传!";
key = false;
}
}
else
{
if (file.exists(pag.server.mappath(url + "/" + newfilename)) == false)
{
//保存文件
producfile.saveas(pag.server.mappath(url + "/" + newfilename));
//返回保存地址
massage = url + "/" + newfilename;//生成缩略图。
for (int j = 0; j < frontname.length; j++)
{
breviaryimg(massage, massage.replace("primary_", frontname[j]), imgwid[j], imghid[j]);
}
key = true;}
else
{
massage = "上传文件名已经存在,请重新上传!";
key = false;
}
}
}
catch
{
massage = "文件上传时出现程序错误,请重新上传!";
key = false;
}}
return key;}
/// <summary>
/// 检测上传文件
/// </summary>
/// <param name="producfile"></param>
/// <param name="size">允许上传最大值</param>
/// <param name="massage">检测信息</param>
/// <returns></returns>
private int throwimg(fileupload producfile, int size, out string massage)
{
int i = 0;boolean imgok = false;
if (producfile.hasfile)
{
//图片类型集
string[] imgextension = { ".gif", ".jpg", ".jpeg", ".png" };
//文件类型
string filetype = producfile.postedfile.contenttype;
//文件扩展名
string fileextype = path.getextension(producfile.filename).tolower();
//匹配类型
for (int k = 0; k < imgextension.length; k++)
{
if (fileextype == imgextension[k])
{
foreach (string type in imgtype)
{
if (filetype == type)
{
imgok = true;
break;
}
}
}
}
if (imgok == true)
{
//获取文件大小
int filesize = producfile.postedfile.contentlength;
if (filesize < size)
{
i = 1;
massage = "";
}
else
{
massage = "上传文件过大!";
i = 0;
}
}
else
{
massage = "上传的文件的格式不合法!";
i = 0;
}
}
else
{
massage = "请选择正确的文件路径!";
i = 0;
}
return i;}
/// <summary>
/// 生成缩缩略图
/// </summary>
/// <param name="imagepath">原图路径</param>
/// <param name="savepath">缩略图存储路径</param>
/// <param name="wid">缩略图宽</param>
/// <param name="hid">缩略图高</param>
private void breviaryimg(string imagepath, string savepath, int wid, int hid)
{
string originalimagepath = pag.server.mappath(imagepath);
string thumbnailpath = pag.server.mappath(savepath);
system.drawing.image originalimage = system.drawing.image.fromfile(originalimagepath);
//int towidth = wid;
//int toheight = hid;int x = 0;
int y = 0;
int ow = originalimage.width;
int oh = originalimage.height;
//新建一个bmp图片
system.drawing.image bitmap = new system.drawing.bitmap(wid, hid);//新建一个画板
system.drawing.graphics g = system.drawing.graphics.fromimage(bitmap);//设置高质量插值法
g.interpolationmode = system.drawing.drawing2d.interpolationmode.high;//设置高质量,低速度呈现平滑程度
g.smoothingmode = system.drawing.drawing2d.smoothingmode.highquality;//清空画布并以透明背景色填充
g.clear(system.drawing.color.transparent);//在指定位置并且按指定大小绘制原图片的指定部分
g.drawimage(originalimage, new system.drawing.rectangle(0, 0, wid, hid), new system.drawing.rectangle(x, y, ow, oh), system.drawing.graphicsunit.pixel);try
{//以原格式保存缩略图
bitmap.save(thumbnailpath, originalimage.rawformat);
}
catch (system.exception e)
{
throw e;
}
finally
{
originalimage.dispose();
bitmap.dispose();
g.dispose();
}
}
}
补充：asp.net教程,.Net开发
