我想要做的是将图片从服务器发送到客户端（Web浏览器）。因此，当我在浏览器中打开链接时，例如https://localhost:8080/geoserver/（我在开始时将端口设置为8080）它将显示消息“hello world”，这很好，但现在我正在尝试使用StreamWriter和所有我发送图像得到的是像System.Drawing.Bitmap这样的文字，浏览器中没有显示图片。我正在使用c＃console应用程序。
我的代码：
static void Main(string[] args)
{
HttpListener listen = new HttpListener();
string url = "http://localhost";
string port = "";
Console.Write("Nastavite port:");
port = Console.ReadLine();
url = url + ":" + port + "/geoserver/";
listen.Prefixes.Add(url);
listen.Start();
while (true)
{
Console.WriteLine("Cakam...");
HttpListenerContext kontekst = listen.GetContext();
string msg = "hello world";
kontekst.Response.ContentLength64 = Encoding.UTF8.GetByteCount(msg);
kontekst.Response.StatusCode = (int)HttpStatusCode.OK;
using(Stream stream = kontekst.Response.OutputStream)
{
using(StreamWriter writer = new StreamWriter(stream))
{
writer.Write(msg);
}
}
Console.WriteLine("Sporočilo poslano");
}
}
您可以通过将图像转换为base64并将其显示在html img标记中来实现。
1）使用System.Drawing库将图片作为字节数组
Image image = Image.FromFile("test-img.jpg");
MemoryStream ms = new MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
byte[] imgBytes = ms.ToArray();
2）需要将其转换为base64字符串后
string base64 = Convert.ToBase64String(imgBytes);
3）然后创建html响应文本
string html = $"<html><img src=\"data: image / png; base64, {base64} \"></html>";
4）现在您可以将此文本写入输出流
Stream stream = kontekst.Response.OutputStream;
StreamWriter writer = new StreamWriter(stream);
writer.WriteLine(html);
所以完整的工作代码看起来像这样
static void Main(string[] args)
{
HttpListener listen = new HttpListener();
string url = "http://localhost";
string port = "";
Console.Write("Nastavite port:");
port = Console.ReadLine();
url = url + ":" + port + "/geoserver/";
listen.Prefixes.Add(url);
listen.Start();
while (true)
{
Console.WriteLine("Cakam...");
HttpListenerContext kontekst = listen.GetContext();
kontekst.Response.StatusCode = (int)HttpStatusCode.OK;
using (Stream stream = kontekst.Response.OutputStream)
using (Image image = Image.FromFile("test-img.jpg"))
using (MemoryStream ms = new MemoryStream())
using (StreamWriter writer = new StreamWriter(stream))
{
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
string base64 = Convert.ToBase64String(ms.ToArray());
writer.WriteLine($"<html><img src=\"data: image / png; base64, {base64} \"></html>");
}
Console.WriteLine("Sporočilo poslano");
}
}
使代码工作所需的最小更改是使用Save方法将图像写入流，而不是Writer.Write()，它将调用对象的ToString()（如果它还不是字符数组），从而导致发送类你经历过的名字。
//Can't set the response length upfront, if you really need to set it you need to
//calculate it from the size of the image.
//kontekst.Response.ContentLength64 = Encoding.UTF8.GetByteCount(msg);
//Most browsers figure it out without this, but good practice to set the type:
kontekst.Response.ContentType = "image/bmp";
kontekst.Response.StatusCode = (int)HttpStatusCode.OK;
var img = Image.FromFile(@"some.bmp");
using (Stream stream = kontekst.Response.OutputStream)
{
img.Save(stream, ImageFormat.Bmp);
}
我还会考虑改变其他一些事情：
System.Drawing.Bitmap而不是System.Drawing.Image。或者甚至更好，如果您不需要将其视为服务器端的图像，只需使用FileStream读取它并将其写入输出流。