目录
为什么要把两者拿出来pk呢？那是因为WebClient已经在.NET 6.0以后得版本被弃用了，一旦在.NET 6.0以上的框架下使用时，会产生SYSLIB0014 警告。虽然可以根据提示采取措施禁止警告，但已经是不正常的状态了。
SYSLIB0014 警告 - .NET | Microsoft Learn
从 .NET 6 开始，将以下 API 标记为已过时。 在代码中使用这些 API 会在编译时生成警告 SYSLIB0014。并提示解决方法：请改用 HttpClient。
WebRequest()
System.Net.WebRequest.Create
System.Net.WebRequest.CreateHttp
System.Net.WebRequest.CreateDefault(Uri)
HttpWebRequest(SerializationInfo, StreamingContext)
System.Net.ServicePointManager.FindServicePoint
WebClient()
一、WebClient 类
命名空间:System.Net。提供用于将数据发送到由 URI 标识的资源及从这样的资源接收数据的常用方法。
类 WebClient 提供用于将数据发送到或从 URI 标识的任何本地、Intranet 或 Internet 资源接收数据的常用方法。
类 WebClient 使用 WebRequest 类提供对资源的访问权限。 WebClient实例可以访问使用 方法注册WebRequest.RegisterPrefix的任何WebRequest后代的数据。
1.WebClient 将数据上传到资源的方法
2.WebClient 从资源下载数据的方法
3.示例源码
// WebClient
// .NET 4.8控制台应用
// The following code example creates a WebClient instance
// and then uses it to download data from a server and display it on the system console,
// to download data from a server and write it to a file,
// and to upload form values to a server and receive the response.
using System;
using System.Collections.Specialized;
using System.Net;
using System.Text;
namespace ConsoleApp2
{
internal class Program
{
static void Main(string[] args)
{
try
{
// Download the data to a buffer.
WebClient client = new WebClient();
byte[] pageData = client.DownloadData("http://www.contoso.com");
string pageHtml = Encoding.ASCII.GetString(pageData);
Console.WriteLine(pageHtml);
// Download the data to a file.
client.DownloadFile("http://www.contoso.com", "page.htm");
// Upload some form post values.
NameValueCollection form = new NameValueCollection
{
{ "MyName", "MyValue" }
};
byte[] responseData = client.UploadValues("http://www.contoso.com/form.aspx", form);
}
catch (WebException webEx)
{
Console.WriteLine(webEx.ToString());
if (webEx.Status == WebExceptionStatus.ConnectFailure)
{
Console.WriteLine("Are you behind a firewall? If so, go through the proxy server.");
}
}
}
}
}
4.生成效果
<html>
<head>
<title>Microsoft Corporation</title>
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7"></meta>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"></meta><meta name="SearchTitle" content="Microsoft.com" scheme=""></meta>
<meta name="Description" content="Get product information, support, and news from Microsoft." scheme=""></meta>
<meta name="Title" content="Microsoft.com Home Page" scheme=""></meta>
<meta name="Keywords" content="Microsoft, product, support, help, training, Office, Windows, software, download, trial, preview, demo, business, security, update, free, computer, PC, server, search, download, install, news" scheme=""></meta>
<meta name="SearchDescription" content="Microsoft.com Homepage" scheme=""></meta>
</head>
<body>
<p>Your current User-Agent string appears to be from an automated process, if this is incorrect, please click this link:<a href="http://www.microsoft.com/en/us/default.aspx?redir=true">United States English Microsoft Homepage</a></p>
</body>
</html>二、HttpClient 类
命名空间:System.Net.Http。一个用于从 URI 标识的资源发送 HTTP 请求和接收 HTTP 响应的类。
1.示例源码
// HttpClient
// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
// Call asynchronous network methods in a try/catch block to handle exceptions.
namespace test1
{
class Program
{
static readonly HttpClient client = new();
static async Task Main()
{
try
{
using HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
response.EnsureSuccessStatusCode();
string responseBody = await response.Content.ReadAsStringAsync();
// Above three lines can be replaced with new helper method below
// string responseBody = await client.GetStringAsync(uri);
Console.WriteLine(responseBody);
}
catch (HttpRequestException e)
{
Console.WriteLine("\nException Caught!");
Console.WriteLine("Message :{0} ", e.Message);
}
}
}
}2.生成效果
// 运行结果
<html>
<head>
<title>Microsoft Corporation</title>
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7"></meta>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"></meta>
<meta name="SearchTitle" content="Microsoft.com" scheme=""></meta>
<meta name="Description" content="Get product information, support, and news from Microsoft." scheme=""></meta>
<meta name="Title" content="Microsoft.com Home Page" scheme=""></meta>
<meta name="Keywords" content="Microsoft, product, support, help, training, Office, Windows, software, download, trial, preview, demo, business, security, update, free, computer, PC, server, search, download, install, news" scheme=""></meta>
<meta name="SearchDescription" content="Microsoft.com Homepage" scheme=""></meta>
</head>
<body>
<p>Your current User-Agent string appears to be from an automated process, if this is incorrect, please click this link:<ahref="http://www.microsoft.com/en/us/default.aspx?redir=true">United States English Microsoft Homepage</a></p>
</body>
</html>