HttpMessageHandler

CS029_Networking/4.HttpMessageHandler/.vscode/launch.json

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+{
+   // Use IntelliSense to find out which attributes exist for C# debugging
+   // Use hover for the description of the existing attributes
+   // For further information visit https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md
+   "version": "0.2.0",
+   "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            // If you have changed target frameworks, make sure to update the program path.
+            "program": "${workspaceFolder}/bin/Debug/netcoreapp2.1/HttpClientExample.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}",
+            // For more information about the 'console' field, see https://aka.ms/VSCode-CS-LaunchJson-Console
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach",
+            "processId": "${command:pickProcess}"
+        }
+    ]
+}

CS029_Networking/4.HttpMessageHandler/.vscode/tasks.json

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+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/HttpClientExample.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/HttpClientExample.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "${workspaceFolder}/HttpClientExample.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

CS029_Networking/4.HttpMessageHandler/HttpClientExample.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="4.5.1" />
+  </ItemGroup>
+
+</Project>

CS029_Networking/4.HttpMessageHandler/Program.cs

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+using System;
+using System.Net;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Threading;
+using System.Threading.Tasks;
+namespace HttpClientHandlerExample {
+
+    class Program {
+        static CookieContainer cookieContainer = new CookieContainer (); // Sử dụng CookieContainer riêng, để lưu lại Cookie - hoặc thêm cookie
+
+        //nested class - MyHttpClientHandler
+        public class MyHttpClientHandler : HttpClientHandler {
+
+            // Khởi tạo và thiết lập cho handler
+            public MyHttpClientHandler (CookieContainer cookie_container) {
+
+                CookieContainer = cookie_container; // Thay thế CookieContainer mặc định
+                AllowAutoRedirect = false; // không cho tự động Redirect
+                AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip; // Chấp nhận nén dữ liệu
+                UseCookies = true;
+            }
+
+            // Nạp chồng SendAsync
+            protected override async Task<HttpResponseMessage> SendAsync (HttpRequestMessage request, CancellationToken cancellationToken) {
+                ShowHeaders ("Request header trước khi qua Handler ", request.Headers);
+
+                var task = base.SendAsync (request, cancellationToken); // gọi SendAsync của lớp cơ sở (bắt buộc)
+                await task;
+
+                ShowHeaders ("Request header sau khi qua Handler ", request.Headers);
+
+                // Xem Cookie nếu  có
+                // var uri = request.RequestUri;
+                // var cookieHeader = CookieContainer.GetCookieHeader(uri);
+                // Console.WriteLine(cookieHeader); 
+
+                return task.Result;
+            }
+        }
+
+        // In thông tin Header
+        public static void ShowHeaders (string lable, HttpHeaders headers) {
+            Console.WriteLine (lable);
+            foreach (var header in headers) {
+                string value = string.Join (" ", header.Value);
+                Console.WriteLine ($"{header.Key,20} : {value}");
+            }
+            Console.WriteLine ();
+
+        }
+
+        public static async Task<string> GetWebContent (string url) {
+            using (var myHttpClientHandler = new MyHttpClientHandler (cookieContainer))
+            using (var httpClient = new HttpClient (myHttpClientHandler)) {
+
+                Console.WriteLine ($"Starting connect {url}");
+                httpClient.DefaultRequestHeaders.Add ("Accept", "text/html,application/xhtml+xml+json");
+                httpClient.DefaultRequestHeaders.Add ("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36");
+                HttpResponseMessage response = await httpClient.GetAsync (url);
+
+                response.EnsureSuccessStatusCode ();
+                string htmltext = await response.Content.ReadAsStringAsync ();
+                return htmltext;
+            }
+        }
+
+        static void Main (string[] args) {
+            string url = "https://www.google.com.vn/";
+
+            cookieContainer.Add (new Uri (url), new Cookie ("NameCookie", "ValueCookie")); // Thêm Cookie khi gửi Requests    
+
+            var htmltask = GetWebContent (url);
+            htmltask.Wait (); // cho hoàn thành tác vụ
+            var html = htmltask.Result; // đọc chuỗi trả về (content)
+            Console.WriteLine (html != null ? html.Substring (0, 150) : "Lỗi");
+        }
+
+    }
+}