System.Net.WebClient Class

Overview

Methods

Properties

Remarks

Example

The WebClient class provides common methods for sending data to and receiving data from a resource identified by a URI.

Simple API for downloading and uploading data.
Supports synchronous and asynchronous operations.
Handles HTTP, FTP, and file protocols.

Method	Signature	Description
DownloadString	string DownloadString(string address)	Downloads the resource as a string.
DownloadData	byte[] DownloadData(string address)	Downloads the resource as a byte array.
UploadString	string UploadString(string address, string data)	Uploads a string to the resource and returns the response as a string.
UploadFile	byte[] UploadFile(string address, string fileName)	Uploads a local file to the resource.
OpenRead	Stream OpenRead(string address)	Opens a readable stream for the resource.
OpenWrite	Stream OpenWrite(string address)	Opens a writable stream for the resource.
DownloadStringAsync	void DownloadStringAsync(Uri uri)	Begins an asynchronous download of a string.
UploadStringAsync	void UploadStringAsync(Uri uri, string method, string data)	Begins an asynchronous upload of a string.

Property	Type	Description
BaseAddress	string	Gets or sets the base URI for requests made by the WebClient.
Credentials	ICredentials	Gets or sets the authentication credentials for the request.
Headers	WebHeaderCollection	Gets the collection of HTTP headers associated with the request.
Encoding	Encoding	Gets or sets the encoding used to convert strings to and from bytes.
Proxy	IWebProxy	Gets or sets the proxy used for requests.

The WebClient class simplifies common tasks such as downloading files, uploading data, and interacting with web services. It automatically handles the underlying WebRequest objects and provides higher-level methods.

When using asynchronous methods, handle the DownloadStringCompleted, UploadStringCompleted, and related events to process results and errors.

Downloading a Web Page

using System;
using System.Net;

class Program
{
    static void Main()
    {
        using (WebClient client = new WebClient())
        {
            client.Encoding = System.Text.Encoding.UTF8;
            string html = client.DownloadString("https://example.com");
            Console.WriteLine(html);
        }
    }
}

Uploading JSON Data (Async)

using System;
using System.Net;
using System.Text;

class AsyncUpload
{
    static void Main()
    {
        WebClient client = new WebClient();
        client.Headers[HttpRequestHeader.ContentType] = "application/json";
        client.UploadStringCompleted += (s, e) =>
        {
            if (e.Error == null)
                Console.WriteLine("Response: " + e.Result);
        };
        string json = "{\"name\":\"John\",\"age\":30}";
        client.UploadStringAsync(new Uri("https://api.example.com/users"), "POST", json);
        Console.ReadLine();
    }
}