MemoryStream的介绍:http://www.cnblogs.com/JimmyZheng/archive/2012/04/14/2446507.html
bitmap.Save(strOutputPathJpg, System.Drawing.Imaging.ImageFormat.Png);
using (Bitmap bmp = new Bitmap(@"D:\map\v10-841-142-1357879384609.jpg"))
{
ImageFormat format = bmp.RawFormat;
Console.WriteLine(format);
Console.WriteLine();
}
虽然扩展名为jpg 但确实是PNG
判断依据是:Guid互相对应。。。这里的GUID是怎么规定的 how why
下一次再试一次。
bmp Guid = {b96b3cab-0728-11d3-9d7b-0000f81ef32e}
emf Guid = {b96b3cac-0728-11d3-9d7b-0000f81ef32e}
exif Guid = {b96b3cb2-0728-11d3-9d7b-0000f81ef32e}
gif Guid = {b96b3cb0-0728-11d3-9d7b-0000f81ef32e}
Guid = {b96b3cb5-0728-11d3-9d7b-0000f81ef32e} icon
Guid = {b96b3cae-0728-11d3-9d7b-0000f81ef32e} jepg
Guid = {b96b3caa-0728-11d3-9d7b-0000f81ef32e} memorymap
Guid = {b96b3caf-0728-11d3-9d7b-0000f81ef32e} png
Guid = {b96b3cb1-0728-11d3-9d7b-0000f81ef32e} tiff
Guid = {b96b3cad-0728-11d3-9d7b-0000f81ef32e} wmf
![](//images0.cnblogs.com/blog/316046/201301/11125803-775be77b7d1043ba82e1d757b83a9143.jpg)
图片下载的标准写法
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
namespace cn.tianditu.crawl.tile.core
{
public class HttpUtil
{
public static void DownImg(TileUri uri)
{
HttpWebResponse response = null;
Stream stream = null;
FileStream writer = null;
try
{
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri.Url);
request.Timeout = 60 * 1000;
response = (HttpWebResponse)request.GetResponse();
uri.HttpStatus = response.StatusCode;
if (response.StatusCode != HttpStatusCode.OK)
{
Console.WriteLine(response.StatusCode);
return;
}
stream = response.GetResponseStream();
using (Image bitmap = Image.FromStream(stream))//如果不是图片这里会异常
{
String ext = RecognizeImgExtName(bitmap.RawFormat);
String imgFileName = uri.FileNameNoExt + ext;
using (MemoryStream ms = new MemoryStream())
{
bitmap.Save(ms, bitmap.RawFormat);
Byte[] bytes = ms.ToArray();
int size = bytes.Length;//可以在这里根据图像大小进行过滤
writer = new FileStream(imgFileName, FileMode.OpenOrCreate, FileAccess.Write);
writer.Write(bytes, 0, size);
}
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
uri.DownFailedReason = e;
}
finally
{
if (writer != null)
{
writer.Close();
writer.Dispose();
}
if (stream != null)
{
stream.Close();
stream.Dispose();
}
if (response != null)
{
response.Close();
}
}
}
private static string RecognizeImgExtName(ImageFormat imageFormat)
{
if (imageFormat.Equals(ImageFormat.Png))
{
return ".png";
}
else if (imageFormat.Equals(ImageFormat.Jpeg))
{
return ".jpg";
}
else if (imageFormat.Equals(ImageFormat.Bmp))
{
return ".bmp";
}
else if (imageFormat.Equals(ImageFormat.Gif))
{
return ".gif";
}
else if (imageFormat.Equals(ImageFormat.Icon))
{
return ".icon";
}
else if (imageFormat.Equals(ImageFormat.Exif))
{
return ".exif";
}
else if (imageFormat.Equals(ImageFormat.Tiff))
{
return ".tiff";
}
else if (imageFormat.Equals(ImageFormat.Emf))
{
return ".emf";
}
throw new Exception("不能识别的图片格式(ImageFormat)");
}
}
}