[英]How to properly make a http web GET request
我还是 C# 新手,我正在尝试为此页面创建一个应用程序,当我收到通知(已回答、评论等)时会告诉我。 但现在我只是想对 api 进行一个简单的调用,它将获取用户的数据。
我正在使用 Visual Studio express 2012 构建 C# 应用程序,其中(现在)您输入您的用户 ID,因此应用程序将使用用户 ID 发出请求并显示该用户 ID 的统计信息。
这是我尝试提出请求的代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//Request library
using System.Net;
using System.IO;
namespace TestApplication
{
class Connect
{
public string id;
public string type;
protected string api = "https://api.stackexchange.com/2.2/";
protected string options = "?order=desc&sort=name&site=stackoverflow";
public string request()
{
string totalUrl = this.join(id);
return this.HttpGet(totalUrl);
}
protected string join(string s)
{
return api + type + "/" + s + options;
}
protected string get(string url)
{
try
{
string rt;
WebRequest request = WebRequest.Create(url);
WebResponse response = request.GetResponse();
Stream dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
rt = reader.ReadToEnd();
Console.WriteLine(rt);
reader.Close();
response.Close();
return rt;
}
catch(Exception ex)
{
return "Error: " + ex.Message;
}
}
public string HttpGet(string URI)
{
WebClient client = new WebClient();
// Add a user agent header in case the
// requested URI contains a query.
client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
Stream data = client.OpenRead(URI);
StreamReader reader = new StreamReader(data);
string s = reader.ReadToEnd();
data.Close();
reader.Close();
return s;
}
}
}
该类是一个对象,只需解析用户 ID 并发出请求即可从表单访问它。
我已经尝试了许多我在谷歌上看过的例子,但不知道为什么我会收到这条消息“ ”。
我是这种算法的新手,如果有人可以分享一本书或教程来展示如何做这种事情(解释每一步),我将不胜感激
服务器有时会压缩它们的响应以节省带宽,当发生这种情况时,您需要在尝试读取响应之前解压缩响应。 幸运的是,.NET 框架可以自动执行此操作,但是,我们必须打开该设置。
这是一个如何实现这一目标的示例。
string html = string.Empty;
string url = @"https://api.stackexchange.com/2.2/answers?order=desc&sort=activity&site=stackoverflow";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.AutomaticDecompression = DecompressionMethods.GZip;
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
using (Stream stream = response.GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
{
html = reader.ReadToEnd();
}
Console.WriteLine(html);
得到
public string Get(string uri)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
using(Stream stream = response.GetResponseStream())
using(StreamReader reader = new StreamReader(stream))
{
return reader.ReadToEnd();
}
}
获取异步
public async Task<string> GetAsync(string uri)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
using(Stream stream = response.GetResponseStream())
using(StreamReader reader = new StreamReader(stream))
{
return await reader.ReadToEndAsync();
}
}
邮政
如果您希望使用 PUT、DELETE、ETC 等其他 HTTP 方法,则包含参数method
public string Post(string uri, string data, string contentType, string method = "POST")
{
byte[] dataBytes = Encoding.UTF8.GetBytes(data);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
request.ContentLength = dataBytes.Length;
request.ContentType = contentType;
request.Method = method;
using(Stream requestBody = request.GetRequestStream())
{
requestBody.Write(dataBytes, 0, dataBytes.Length);
}
using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
using(Stream stream = response.GetResponseStream())
using(StreamReader reader = new StreamReader(stream))
{
return reader.ReadToEnd();
}
}
POST 异步
如果您希望使用 PUT、DELETE、ETC 等其他 HTTP 方法,则包含参数method
public async Task<string> PostAsync(string uri, string data, string contentType, string method = "POST")
{
byte[] dataBytes = Encoding.UTF8.GetBytes(data);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
request.ContentLength = dataBytes.Length;
request.ContentType = contentType;
request.Method = method;
using(Stream requestBody = request.GetRequestStream())
{
await requestBody.WriteAsync(dataBytes, 0, dataBytes.Length);
}
using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
using(Stream stream = response.GetResponseStream())
using(StreamReader reader = new StreamReader(stream))
{
return await reader.ReadToEndAsync();
}
}
另一种方法是像这样使用“HttpClient”:
using System;
using System.Net;
using System.Net.Http;
namespace Test
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Making API Call...");
using (var client = new HttpClient(new HttpClientHandler { AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate }))
{
client.BaseAddress = new Uri("https://api.stackexchange.com/2.2/");
HttpResponseMessage response = client.GetAsync("answers?order=desc&sort=activity&site=stackoverflow").Result;
response.EnsureSuccessStatusCode();
string result = response.Content.ReadAsStringAsync().Result;
Console.WriteLine("Result: " + result);
}
Console.ReadLine();
}
}
}
检查的HttpClient VS HttpWebRequest的距离计算器以及这种从其他。
2020 年 6 月 22 日更新:不建议在“使用”块中使用 httpclient,因为它可能会导致端口耗尽。
private static HttpClient client = null;
ContructorMethod()
{
if(client == null)
{
HttpClientHandler handler = new HttpClientHandler()
{
AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
};
client = new HttpClient(handler);
}
client.BaseAddress = new Uri("https://api.stackexchange.com/2.2/");
HttpResponseMessage response = client.GetAsync("answers?order=desc&sort=activity&site=stackoverflow").Result;
response.EnsureSuccessStatusCode();
string result = response.Content.ReadAsStringAsync().Result;
Console.WriteLine("Result: " + result);
}
如果使用 .Net Core 2.1+,请考虑使用IHttpClientFactory并在启动代码中像这样注入。
var timeout = Policy.TimeoutAsync<HttpResponseMessage>(
TimeSpan.FromSeconds(60));
services.AddHttpClient<XApiClient>().ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler
{
AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
}).AddPolicyHandler(request => timeout);
我的意见最简单的方式
var web = new WebClient();
var url = $"{hostname}/LoadDataSync?systemID={systemId}";
var responseString = web.DownloadString(url);
或者
var bytes = web.DownloadData(url);
var request = (HttpWebRequest)WebRequest.Create("sendrequesturl");
var response = (HttpWebResponse)request.GetResponse();
string responseString;
using (var stream = response.GetResponseStream())
{
using (var reader = new StreamReader(stream))
{
responseString = reader.ReadToEnd();
}
}
添加到已经给出的响应中,这是一个完整的示例,访问JSON PlaceHolder站点。
using System;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json;
namespace Publish
{
class Program
{
static async Task Main(string[] args)
{
// Get Reqeust
HttpClient req = new HttpClient();
var content = await req.GetAsync("https://jsonplaceholder.typicode.com/users");
Console.WriteLine(await content.Content.ReadAsStringAsync());
// Post Request
Post p = new Post("Some title", "Some body", "1");
HttpContent payload = new StringContent(JsonConvert.SerializeObject(p));
content = await req.PostAsync("https://jsonplaceholder.typicode.com/posts", payload);
Console.WriteLine("--------------------------");
Console.WriteLine(content.StatusCode);
Console.WriteLine(await content.Content.ReadAsStringAsync());
}
}
public struct Post {
public string Title {get; set;}
public string Body {get;set;}
public string UserID {get; set;}
public Post(string Title, string Body, string UserID){
this.Title = Title;
this.Body = Body;
this.UserID = UserID;
}
}
}
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