< C++ Http Post Request Program Example | Main | VB .NET Http Post Request Program Example >


 

Chapter 10 Part 6:

HTTP with .NET

 

 

What do we have in this chapter 10 Part 6?

  1. C# Http Post Request Program Example

 

C# Http Post Request Program Example

 

Create a new console application project and you might want to use HttpGetRequestCS as the solution and project names.

 

C# Http Post Request Program Example - creating a new Console application project in VS 2008 IDE

 

 

Rename the source file to HttpPostRequest to reflect the application that we are going to developed.

 

C# Http Post Request Program Example - renaming the source file will automatically rename the class

 

Add the public class access modifier to the HttpPostRequest class.

 

C# Http Post Request Program Example - adding the public access modifier to the class

 

Add the following using directives.

 

using System;

using System.Net;

using System.IO;

using System.Text;

using System.Web;

 

Add the following code for the HttpPostRequestCS class that include the Main() method.

 

namespace HttpPostRequestCS

{

    /// <summary>

    /// Simple class that encapsulates the HTTP post sample.

    /// </summary>

    public class HttpPostRequest

    {

        /// <summary>

        /// Displays simple usage information.

        /// </summary>

        public static void usage()

        {

            Console.WriteLine("Executable_file_name [-u URL] [-d data] [-s file] [-p proxy]");

            Console.WriteLine("Available options:");

            Console.WriteLine("     -u URL          URL to post data to");

            Console.WriteLine("     -d data         Data to post");

            Console.WriteLine("     -s file         File name to save response to");

            Console.WriteLine("     -p HTTP URL     Proxy to use for post operation");

            Console.WriteLine();

        }

 

        /// <summary>

        /// This routine validates the data being posted to the web page. It parses

        /// the string for reserved characters '?', '=', and '&'. The individual

        /// validated parts are returned via a StringBuilder object.

        /// </summary>

        /// <param name="postData">Data to validate</param>

        /// <returns>StringBuilder object representing the parsed elements</returns>

        public static StringBuilder ValidatePostData(string postData)

        {

            StringBuilder encodedPostData = new StringBuilder();

            // These chars should be more...e.g. custom

            char[ ] reservedChars = { '?', '=', '&' };

            int pos, offset;

 

            // Validate the data to be posted

            Console.WriteLine("Validating the data to be posted...");

            offset = 0;

            while (offset < postData.Length)

            {

                pos = postData.IndexOfAny(reservedChars, offset);

                if (pos == -1)

                {

                    // Append the remaining part of the string

                    Console.WriteLine("Appending the remaining part of the string...");

                    encodedPostData.Append(HttpUtility.UrlEncode(postData.Substring(offset, postData.Length - offset)));

                    break;

                }

                // Found a special character so append up to the special character

                Console.WriteLine("Found a special character so append up to the special character...");

                encodedPostData.Append(HttpUtility.UrlEncode(postData.Substring(offset, pos - offset)));

                encodedPostData.Append(postData.Substring(pos, 1));

                offset = pos + 1;

            }

            return encodedPostData;

        }

 

        /// <summary>

        /// This method creates an HttpWebRequest object, sets the method to "POST",

        /// and builds the data to post. Once the HttpWebRequest object is created,

        /// the request stream is obtained and the post data is sent and the

        /// request stream closed. The response is then retrieved.

        /// </summary>

        /// <param name="postUrl">URL to post data to</param>

        /// <param name="postData">Data to post</param>

        /// <param name="proxyServer">Proxy server to use</param>

        /// <param name="saveFile">Filename to save response to</param>

        public static void HttpMethodPost(string postUrl, string postData, IWebProxy proxyServer, string saveFile)

        {

            HttpWebRequest httpRequest = null;

            HttpWebResponse httpResponse = null;

            Stream httpPostStream = null;

            BinaryReader httpResponseStream = null;

            FileStream localFile = null;

 

            try

            {

                StringBuilder encodedPostData;

                byte[ ] postBytes = null;

 

                // Create HTTP web request

                Console.WriteLine("Creating HTTP web request...");

                httpRequest = (HttpWebRequest)WebRequest.Create(postUrl);

                // Change method from the default "GET" to "POST"

                Console.WriteLine("Changing method from the default \"GET\" to \"POST\"...");

                httpRequest.Method = "POST";

                // Posted forms need to be encoded so change the content type

                Console.WriteLine("Changing the content type...");

                httpRequest.ContentType = "application/x-www-form-urlencoded";

                // Set the proxy

                Console.WriteLine("Setting the proxy...");

                httpRequest.Proxy = proxyServer;

                // Validate and encode the data to POST

                Console.WriteLine("Validating and encode the data to POST...");

                encodedPostData = ValidatePostData(postData);

 

                Console.WriteLine("Encoded POST string: '{0}'", encodedPostData.ToString());

 

                // Retrieve a byte array representation of the data

                Console.WriteLine("Retrieving a byte array representation of the data...");

                postBytes = Encoding.UTF8.GetBytes(encodedPostData.ToString());

                // Set the content length (the number of bytes in the POST request)

                Console.WriteLine("Setting the content length - the number of bytes in the POST request...");

                httpRequest.ContentLength = postBytes.Length;

                // Retrieve the request stream so we can write the POST data

                Console.WriteLine("Retrieving the request stream so we can write the POST data...");

                httpPostStream = httpRequest.GetRequestStream();

                // Write the POST request

                Console.WriteLine("Writing the POST request...");

                httpPostStream.Write(postBytes, 0, postBytes.Length);

 

                httpPostStream.Close();

                httpPostStream = null;

 

                // Retrieve the response

                Console.WriteLine("Retrieving the response...");

                httpResponse = (HttpWebResponse)httpRequest.GetResponse();

                // Retrieve the response stream

                Console.WriteLine("Retrieving the response stream...");

                httpResponseStream = new BinaryReader(httpResponse.GetResponseStream(), Encoding.UTF8);

 

                byte[ ] readData;

 

                // Open the file to save the response to

                Console.WriteLine("Opening the file to save the response to...");

                localFile = File.Open(

                    saveFile,

                    System.IO.FileMode.Create,

                    System.IO.FileAccess.Write,

                    System.IO.FileShare.None

                    );

                Console.WriteLine("Saving response to: {0}", localFile.Name);

                Console.Write("Receiving response stream until the end...\n");

                // Receive the response stream until the end

                int count = 0;

                long percent;

 

                while (true)

                {

                    readData = httpResponseStream.ReadBytes(4096);

                    if (readData.Length == 0)

                        break;

                    localFile.Write(readData, 0, readData.Length);

                    // Calculate the progress and display to the console

                    Console.Write("Calculating the progress and display to the console...\n");

                    count += readData.Length;

                    percent = (count * 100) / httpResponse.ContentLength;

                    Console.Write("\b\b\b");

                    Console.Write(@"{0}%", percent.ToString().PadLeft(2));

                }

                Console.WriteLine();

            }

            catch (WebException wex)

            {

                Console.WriteLine("HttpMethodPost() - Exception occurred: {0}", wex.ToString());

                httpResponse = (HttpWebResponse)wex.Response;

            }

            finally

            {

                // Close any remaining resources

                Console.Write("Closing any remaining resources...\n");

                if (httpResponse != null)

                {

                    httpResponse.Close();

                }

                if (localFile != null)

                {

                    localFile.Close();

                }

            }

        }

 

        /// <summary>

        /// This is the main routine that parses the command line and calls routines to

        /// issue the POST request and receive the response.

        /// </summary>

        /// <param name="args">Command line arguments</param>

        static void Main(string[] args)

        {

            // Example: http://search.live.com/

            //          results.aspx?q=tenouk&go=&form=QBLH

            //          http://search.msdn.microsoft.com/

            //          Default.aspx?query=web&brand=msdn&locale=en-us&refinement=

            IWebProxy proxyServer;

            string uriToPost = "http://search.live.com/",

                    proxyName = null,

                    postData = "results.aspx?q=tenouk&go=&form",

                    fileName = null;

 

            usage();

 

            // Parse the command line

            for (int i = 0; i < args.Length; i++)

            {

                try

                {

                    if ((args[i][0] == '-') || (args[i][0] == '/'))

                    {

                        switch (Char.ToLower(args[i][1]))

                        {

                            case 'u':

                                // URI to post to

                                uriToPost = args[++i];

                                break;

                            case 'p':

                                // Name of proxy server to use

                                proxyName = args[++i];

                                break;

                            case 'd':

                                // Retrieve all referenced images and text on the same host

                                postData = args[++i];

                                break;

                            case 's':

                                // Local save path to append to retrieved resources

                                fileName = args[++i];

                                break;

                            default:

                                usage();

                                return;

                        }

                    }

                }

                catch

                {

                    usage();

                    return;

                }

            }

 

            try

            {

                // Set the proxy if supplied or use the default IE static proxy

                Console.Write("Setting the proxy if supplied or use the default IE static proxy...\n");

                if (proxyName == null)

                {

                    proxyServer = WebRequest.DefaultWebProxy;

                }

                else

                {

                    proxyServer = new WebProxy(proxyName);

                }

                // Post the request and write the response to the file

                Console.Write("Posting the request and write the response to the file...\n");

                HttpMethodPost(uriToPost, postData, proxyServer, fileName);

            }

            catch (Exception ex)

            {

                Console.WriteLine("Main() - Exception occurred: {0}", ex.Message);

            }

            return;

        }

    }

}

 

 

 

 

 

Build the project. There is an error stating that 'HttpUtility' is not in the context. It seems that the System.Web cannot resolve the reference. To solve this, let add a reference to the Web.dll manually. Select the project folder > Right click mouse > Select Add Reference context menu.

 

C# Http Post Request Program Example - invoking the Add Reference page

 

Find the System.Web (Web.dll) under the .NET tab and click OK.

 

C# Http Post Request Program Example - selecting the System.Web component (Web.dll)

 

Re-build the project. The previous error should disappear.

 

C# Http Post Request Program Example - building the project

 

Run the project.

 

C# Http Post Request Program Example - running the project  

 

The following is the output sample using default argument values.

 

C# Http Post Request Program Example - a sample output with default argument values

 

The following output sample generated when running the program from command prompt using the following arguments.

C:\>httppostrequestcs -u http://search.msdn.microsoft.com/ -d Default.aspx?Query=web.dll -s test.htm

C# Http Post Request Program Example - another sample output with the supplied arguments

 

The following is another sample output.

 

C# Http Post Request Program Example - a sample output with an exception thrown

 

 

 


 

< C++ Http Post Request Program Example | Main | VB .NET Http Post Request Program Example >