参考出处：http://bbs.esrichina-bj.cn/ESRI/thread-59271-1-1.html
使用上面提供的方法需要注意的地方：
1：url路径可能不对需要自己根据情况调整下。
2：有的图层可能需要传入token
GetUrl方法需要修改
private static string GetUrl(PrintArea area, string url,string token)
{
StringBuilder uri = new StringBuilder();
uri.AppendFormat("{0}/export?", url);
uri.AppendFormat(System.Globalization.CultureInfo.InvariantCulture,
"bbox={0},{1},{2},{3}", area.XMin, area.YMin, area.XMax, area.YMax);
uri.AppendFormat("&size={0},{1}", area.Width, area.Height);
uri.Append("&format=png32");
uri.Append("&transparent=true");
if (area.SpatialReferenceID.HasValue)
{
uri.AppendFormat("&imageSR={0}&bboxSR={0}", area.SpatialReferenceID);
}
uri.Append("&f=image");
uri.Append("&token=" + token);
return uri.ToString();
} 3 .奖生成的图片转成stream的时候要用ImageFormat.Png，如果是mageFormat.jpeg那么所有透明的地方都会被黑色替代
MemoryStream stream = new MemoryStream();
image.Save(stream, ImageFormat.Png);
byte[] data = new byte[(int)stream.Length]; 4：下载图片
protected void Button1_Click(object sender, EventArgs e)
{
WebClient client = new WebClient();
string id = Request.QueryString[0];
string url = "http://" + Request.Url.Authority + "/GetImagePrint.ashx?id="+id;
WebClient wc = new WebClient();
var bytes = wc.DownloadData(url);
Response.Buffer = true;
Page.Response.Clear();//清除缓冲区所有内容
Page.Response.ContentType = "application/octet-stream";
Page.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode("print.jpg"));
byte[] file = bytes;
int a = file.Length;
Response.BinaryWrite(file);
Response.Flush();
Response.End();
}