在上一篇博文中介绍的Web Server，其实是Socket编程应用，我们这篇文章介绍的是真正的Http Server，支持GET和POST功能。
同样我们还是在官方示例Http Server上进行修改，为了使示例更清晰，我们尽可能把代码做的更简单一些。
主程序直接修改为如下代码：
public static void Main()
{
try
{
RunServer("http");
}
catch (Exception e)
{
Debug.Print(e.Message);
}
}
核心代码就是对GET和POST请求的支持，这里我们不要变，代码如下：
internal static void RunServer(string prefix)
{
HttpListener listener = new HttpListener(prefix, -1);
listener.Start();
while (true)
{
HttpListenerResponse response = null;
HttpListenerContext context = null;
try
{
context = listener.GetContext();
response = context.Response;
HttpListenerRequest request = context.Request;
switch (request.HttpMethod.ToUpper())
{
case "GET": GetRequest(context); break;
case "POST": PostRequest(context); break;
}
if (response != null)
{
response.Close();
}
}
catch
{
if (context != null)
{
context.Close();
}
}
}
}
GET 请求处理代码如下，我们进行了大幅度的简化和调整，并且增加了一个upload.asp处理模块，代码如下：
private static void GetRequest(HttpListenerContext context)
{
HttpListenerRequest request = context.Request;
HttpListenerResponse response = context.Response;
string strFilePath = GetPathFromURL(request.RawUrl);
Debug.Print(strFilePath);
response.StatusCode = (int)HttpStatusCode.OK;
// Start HTML document
string strResp = "<HTML><BODY>.Net Micro Framework Example HTTP Server<p>";
// Print requested verb, URL and version.. Adds information from the request.
strResp += "HTTP Method: " + request.HttpMethod + "<br> Requested URL: \"" + request.RawUrl +
"\"<br> HTTP Version: " + request.ProtocolVersion + "\"<p>";
if (strFilePath.ToLower() == "\\upload.asp")
{
strResp += Resource1.GetString(Resource1.StringResources.PostForm);
}
else
{
strResp += "File to access " + strFilePath + "<p>";
strResp += "Directory: \"" + strFilePath + "\" Does not exists";
}
// Closes HTML
strResp += "</BODY></HTML>";
// Sends it.
byte[] messageBody = Encoding.UTF8.GetBytes(strResp);
response.ContentType = "text/html";
response.OutputStream.Write(messageBody, 0, messageBody.Length);
}
POST处理部分，我们也进行了简化，不过变化不大，相关代码如下：
private static void PostRequest(HttpListenerContext context)
{
// Retrieves request and response.
HttpListenerRequest request = context.Request;
HttpListenerResponse response = context.Response;
// Allocates buffer for reading of message body
byte[] postdata = new byte[BUFFER_SIZE];
// Now reads the posted data. The content length should be supplied.
// It is error not to have content length with post request.
if (request.ContentLength64 > 0)
{
Debug.Print("Request Headers:");
Debug.Print(request.Headers.ToString());
long totalBytesReceived = 0;
long contLen = request.ContentLength64;
while (totalBytesReceived < contLen)
{
int bytesToRead = (int)(contLen - totalBytesReceived);
// Limit to buffer size
bytesToRead = bytesToRead < BUFFER_SIZE ? bytesToRead : BUFFER_SIZE;
int dataRead = request.InputStream.Read(postdata, 0, bytesToRead);
if (dataRead == 0)
{
// Definitely some error. Means file incomplete.
break;
}
totalBytesReceived += dataRead;
};
// Sends response:
string strResp = "<HTML><BODY>.Net Micro Framework Example HTTP Server<p>";
// Print requested verb, URL and version.. Adds information from the request.
strResp += "HTTP Method: " + request.HttpMethod + "<br> Requested URL: \"" + request.RawUrl +
"\"<br> HTTP Version: " + request.ProtocolVersion + "\"<p>";
strResp += "Amount of data received in message body: " + totalBytesReceived + "<br>";
strResp += "Data of message body is discarded (if there is no filesystem). Please review HTTP Server sample code to add processing of data";
strResp += "</BODY></HTML>";
response.StatusCode = (int)HttpStatusCode.OK;
byte[] messageBody = Encoding.UTF8.GetBytes(strResp);
response.ContentType = "text/html";
response.OutputStream.Write(messageBody, 0, messageBody.Length);
}
else // Content length is missing, send error back
{
// Sends response:
string strResp = "<HTML><BODY>Content length is missing in Post request</BODY></HTML>";
byte[] messageBody = Encoding.UTF8.GetBytes(strResp);
response.ContentType = "text/html";
response.OutputStream.Write(messageBody, 0, messageBody.Length);
}
}
好了，程序编写好后，直接部署到开发板上进行运行，连接PC，打开IE 浏览器，输入http://192.168.0.100/a.txt，效果如下：
本意是如果存在a.txt文件，则下载a.txt的内容，不过我们在代码中没有处理。
下面演示一下POST的使用，在IE浏览器中输入：http://192.168.0.100/Upload.asp
IE显示的内容如下：
我们随意选择一个文件，然后单击 【Send File Data To Server】按钮，则Http Server处理POST请求，并返回，IE此时会新弹出一个页面，如下图：
在Http Server 的POST处理程序内，我们可以获取上传文件的内容，这里我们没有显示相关内容，只是显示了它的大小，如611个字节。
.NET Micro Framework支持的网络功能还很多，如对WCF的支持，有待我们今后细细研究。
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