I tried this and i want that the source content of the website will be download to a string:
public partial class Form1 : Form
{
WebClient client;
string url;
string[] Search(string SearchParameter);
public Form1()
{
InitializeComponent();
url = "http://chatroll.com/rotternet";
client = new WebClient();
webBrowser1.Navigate("http://chatroll.com/rotternet");
}
private void Form1_Load(object sender, EventArgs e)
{
}
static void DownloadDataCompleted(object sender,
DownloadDataCompletedEventArgs e)
{
}
public string SearchForText(string SearchParameter)
{
client.DownloadDataCompleted += DownloadDataCompleted;
client.DownloadDataAsync(new Uri(url));
return SearchParameter;
}
I want to use WebClient and downloaddataasync and in the end to have the website source content in a string.
No need for async, really:
var result = new System.Net.WebClient().DownloadString(url)
If you don't want to block your UI, you can put the above in a BackgroundWorker. The reason I suggest this rather than the Async methods is because it is dramatically simpler to use, and because I suspect you are just going to stick this string into the UI somewhere anyway (where BackgroundWorker will make your life easier).
If you are using .Net 4.5,
public async void Downloader()
{
using (WebClient wc = new WebClient())
{
string page = await wc.DownloadStringTaskAsync("http://chatroll.com/rotternet");
}
}
For 3.5 or 4.0
public void Downloader()
{
using (WebClient wc = new WebClient())
{
wc.DownloadStringCompleted += (s, e) =>
{
string page = e.Result;
};
wc.DownloadStringAsync(new Uri("http://chatroll.com/rotternet"));
}
}
Using WebRequest:
WebRequest request = WebRequest.Create(url);
request.Method = "GET";
WebResponse response = request.GetResponse();
Stream stream = response.GetResponseStream();
StreamReader reader = new StreamReader(stream);
string content = reader.ReadToEnd();
reader.Close();
response.Close();
You can easily call the code from within another thread, or use background worer - that will make your UI responsive while retrieving data.
Related
I am trying to download a file into my app. From what I can see if I put this link into a browser I get a good file downloaded so I know the file is available for me to get. I have other files to download from different sites and they all work well but this one will not download for me in a usable manner. I guess I do not understand something, do you know the key fact I am missing?
After many attempts I have now coded the following
private string url =
"https://coronavirus.data.gov.uk/api/v1/data?filters=areaType=nation&structure={\"Name\":\"areaName\",\"date\":\"date\",\"FirstDose\":\"cumPeopleVaccinatedFirstDoseByPublishDate\",\"SecondDose\":\"cumPeopleVaccinatedSecondDoseByPublishDate\"}&format=csv";
private void btn_wc1_Click(object sender, EventArgs e)
{
WebClient wc = new WebClient();
wc.Encoding = Encoding.UTF8;
wc.DownloadFile(url, "wc1_uk_data.csv");
}
private void btn_wc2_Click(object sender, EventArgs e)
{
using (var webClient = new WebClient())
{
webClient.Encoding = Encoding.UTF8;
string s = webClient.DownloadString(url);
File.WriteAllText(#"wc2_uk_data.csv", s);
}
}
private async void btn_https_Click(object sender, EventArgs e)
{
HttpClient _client = new HttpClient();
byte[] buffer = null;
try
{
HttpResponseMessage task = await _client.GetAsync(url);
Stream task2 = await task.Content.ReadAsStreamAsync();
using (MemoryStream ms = new MemoryStream())
{
await task2.CopyToAsync(ms);
buffer = ms.ToArray();
}
File.WriteAllBytes("https_uk_data.csv", buffer);
}
catch
{
}
}
private void btn_wc3_Click(object sender, EventArgs e)
{
using (var webClient = new WebClient())
{
webClient.Encoding = Encoding.UTF8;
byte[] myDataBuffer = webClient.DownloadData(url);
MemoryStream ms = new MemoryStream(myDataBuffer);
FileStream f = new FileStream(Path.GetFullPath(Path.Combine(Application.StartupPath, "wc3_uk_data.csv")),
FileMode.OpenOrCreate);
ms.WriteTo(f);
f.Close();
ms.Close();
}
}
Using the following UI
All the different functions above will download a file but none of the downloaded files is usable. It seems like it is not the file but maybe something to do with information regarding the file. As my app does not know what to do with this I never reply with what ever the other end wants. I guess if I replied the next set of data I got would be the file.
If I put the URL into a browser then I get a file that is good. This link is good at the moment.
https://coronavirus.data.gov.uk/api/v1/data?filters=areaType=nation&structure={"Name":"areaName","date":"date","FirstDose":"cumPeopleVaccinatedFirstDoseByPublishDate","SecondDose":"cumPeopleVaccinatedSecondDoseByPublishDate"}&format=csv
Anyone got any idea on what I need to do in my app to get the file like the browser does?
You need to set the WebClient.Encoding before calling DownloadString
string url = "https://coronavirus.data.gov.uk/api/v1/data?filters=areaType=nation&structure={\"Name\":\"areaName\",\"date\":\"date\",\"FirstDose\":\"newPeopleReceivingFirstDose\",\"SecondDose\":\"newPeopleReceivingSecondDose\"}&format=csv";
using (var webClient = new WebClient())
{
webClient.Encoding = Encoding.UTF8;
string s = webClient.DownloadString(url);
}
Here is a related question:
WebClient.DownloadString results in mangled characters due to encoding issues, but the browser is OK
I'm trying to use WebClient.DownloadFileTaskAsync to download a file so that I can make use of the download progress event handlers. The problem is that even though I'm using await on DownloadFileTaskAsync, it's not actually waiting for the task to finish and exits instantly with a 0 byte file. What am I doing wrong?
internal static class Program
{
private static void Main()
{
Download("http://ovh.net/files/1Gb.dat", "test.out");
}
private async static void Download(string url, string filePath)
{
using (var webClient = new WebClient())
{
IWebProxy webProxy = WebRequest.DefaultWebProxy;
webProxy.Credentials = CredentialCache.DefaultCredentials;
webClient.Proxy = webProxy;
webClient.DownloadProgressChanged += (s, e) => Console.Write($"{e.ProgressPercentage}%");
webClient.DownloadFileCompleted += (s, e) => Console.WriteLine();
await webClient.DownloadFileTaskAsync(new Uri(url), filePath).ConfigureAwait(false);
}
}
}
As others have pointed, The two methods shown are either not asynchronous or not awaitable.
First, you need to make your download method awaitable:
private async static Task DownloadAsync(string url, string filePath)
{
using (var webClient = new WebClient())
{
IWebProxy webProxy = WebRequest.DefaultWebProxy;
webProxy.Credentials = CredentialCache.DefaultCredentials;
webClient.Proxy = webProxy;
webClient.DownloadProgressChanged += (s, e) => Console.Write($"{e.ProgressPercentage}%");
webClient.DownloadFileCompleted += (s, e) => Console.WriteLine();
await webClient.DownloadFileTaskAsync(new Uri(url), filePath).ConfigureAwait(false);
}
}
Then, you either wait on Main:
private static void Main()
{
DownloadAsync("http://ovh.net/files/1Gb.dat", "test.out").Wait();
}
Or, make it asynchronous, too:
private static async Task Main()
{
await DownloadAsync("http://ovh.net/files/1Gb.dat", "test.out");
}
Here's the asp.net page which I want to get the response
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
B2.Text = Request.QueryString["webget"];
}
}
Use this code to send the request in Form
private void button1_Click(object sender, EventArgs e)
{
string UrlString = "http://localhost:10694/Default.aspx?webget=more";
HttpWebRequest req = HttpWebRequest.Create(UrlString) as HttpWebRequest;
req.Method = "GET";
string result = "";
try
{
using (HttpWebResponse response = req.GetResponse() as HttpWebResponse)
{
using (StreamReader sr = new StreamReader(response.GetResponseStream()))
{
result = sr.ReadToEnd();
}
}
}
catch
{
label1.Text = "error";
}
label1.Text = result;
}
This code will download and display the Default.aspx
But if I want to return a string from ASP.NET,rather than downloading the page
How to do that in ASP.NET?
Do you mean "Response.Write" function?
https://msdn.microsoft.com/en-us/library/ms525585%28v=vs.90%29.aspx
If you want to return a string in response, try this:
In the page, write:
string rtnString = "yourStringHere";
Response.Write(rtnString);
Response.End();
I'm developping on Windows phone 8 and I would like to know if it's possible to manipulate data in the same method when we call DownloadStringCompleted of WebClient?
private void DownloadDataFromWebService(String uri)
{
WebClient wc = new WebClient();
wc.DownloadStringAsync(new Uri(uri));
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
}
private void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
RootObject r = JsonConvert.DeserializeObject<RootObject>(e.Result);
List<Category> listeCategories = r.Result;
}
Thus, I would like to manage all code in only one method because I would like to return an object
For example,
private List<Category> GetCategories(String uri)
{
WebClient wc = new WebClient();
wc.DownloadStringAsync(new Uri(uri));
.....
.....
RootObject r = JsonConvert.DeserializeObject<RootObject>(e.Result);
return (List<Category>) r.Result;
}
Yes, that is possible, due to magic TaskCompletionSource class, http://msdn.microsoft.com/en-us/library/dd449174(v=vs.95).aspx . To download:
async Task<List<object>> getCategories(String uri)
{
var taskCompletionObj = new TaskCompletionSource<string>();
var wc= new webClient();
wc.DownloadStringAsync(new URI(uri, Urikind.Absolute)) += (o, e) =>
{
taskCompletionObj.TrySetResult(e.Result);
};
string rawString = await taskCompletionObj.Task;
RootObject r = JsonConvert.DeserializeObject<RootObject>(rawString);
return (List<Category>)r.Result;
}
To use: var x = await getCategories(myURI);
How to retrieve a webpage and diplay the html to the console with C# ?
Use the System.Net.WebClient class.
System.Console.WriteLine(new System.Net.WebClient().DownloadString(url));
I have knocked up an example:
WebRequest r = WebRequest.Create("http://www.msn.com");
WebResponse resp = r.GetResponse();
using (StreamReader sr = new StreamReader(resp.GetResponseStream()))
{
Console.WriteLine(sr.ReadToEnd());
}
Console.ReadKey();
Here is another option, using the WebClient this time and do it asynchronously:
static void Main(string[] args)
{
System.Net.WebClient c = new WebClient();
c.DownloadDataCompleted +=
new DownloadDataCompletedEventHandler(c_DownloadDataCompleted);
c.DownloadDataAsync(new Uri("http://www.msn.com"));
Console.ReadKey();
}
static void c_DownloadDataCompleted(object sender,
DownloadDataCompletedEventArgs e)
{
Console.WriteLine(Encoding.ASCII.GetString(e.Result));
}
The second option is handy as it will not block the UI Thread, giving a better experience.
// Save HTML code to a local file.
WebClient client = new WebClient ();
client.DownloadFile("http://yoursite.com/page.html", #"C:\htmlFile.html");
// Without saving it.
string htmlCode = client.DownloadString("http://yoursite.com/page.html");