[ASP.NET] 使用HttpClient來Post WebAPI

2023-04-24

2269
0
C#
2024-02-22

Post WebAPI using HttpClient

前言

隨手備份的Sample Code，不然懶人我每次要使用都得上網查找

↓ ASP.NET Core 2.1+

先自訂義一個自用的Helper類別

using System;
using System.Net;
using System.Net.Http;
using System.Text; 
using Newtonsoft.Json;//須先透過Nuget加入此參考

namespace MyCentralizedWebAPI.Helper
{
    public class MyWebHelper
    {
        private readonly IHttpClientFactory _clientFactory;
        public MyWebHelper(IHttpClientFactory clientFactory)
        {
           _clientFactory = clientFactory;
        }
        private SecurityProtocolType GetSecurityProtocol()
         {
            int result = 0;
     		foreach (var value in Enum.GetValues(typeof(SecurityProtocolType)))
     		{
         		result += (int)value;
     		}//end foreach
     		return (SecurityProtocolType)result;
         }
         
        //content_type為"application/json"的情況
        public  T PostWebApi<T>(string url, object objPostBody)
        {
            //建立 HttpClient
            HttpClient client = _clientFactory.CreateClient();
             //忽略TLS憑證驗證(視需求
            //ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
            //支持TLS連線(視需求
            ServicePointManager.SecurityProtocol = this.GetSecurityProtocol();
            // 指定 authorization header(若有需要的話)
            //client.DefaultRequestHeaders.Add("authorization", "token {api token}");
            // 要Post給WebAPI，傳遞的內容
            HttpContent httpContent = new StringContent(JsonConvert.SerializeObject(objPostBody), Encoding.UTF8, "application/json");
            // 發出 http post 並取得結果
            HttpResponseMessage response = client.PostAsync(url, httpContent).Result;
            // 回應結果字串
            string strResponse =  response.Content.ReadAsStringAsync().Result;
             //字串反序列化為物件
            var result = JsonConvert.DeserializeObject<T>(strResponse);
            if (result==null)
            {//為了消除VS IDE的null警告...
                result = Activator.CreateInstance<T>();
            }
            return result; 
        }
    }
}

我用的是.NET 7，在Program.cs加入服務↓

    var builder = WebApplication.CreateBuilder(args); 
    
    //↓ Add Service
    //MyWebHelper可透過DI使用HttpClient
    builder.Services.AddHttpClient();
    //MyWebHelper類別可以DI給Controller使用(生命週期同為應用程式)
    builder.Services.AddSingleton<MyWebHelper>();

在Controller裡的使用方式↓


        /// <summary>
        /// 讀取組態用
        /// </summary>
        private readonly IConfiguration _config;
        
        private readonly MyWebHelper _MyWebHelper;
        
        #region 建構子
        public YourController(IConfiguration config, MyWebHelper myWebHelper)
        {
            this._config = config; 
            this._MyWebHelper = myWebHelper;
        }
        #endregion


        [HttpPost]
        public IActionResult YourAction(YourClassParam param)
        {
            //從組態檔取得WebAPI網址
            string url = this._config.GetValue<string>("yourWebAPIUrl") ?? "";
            //http post給另一系統的WebAPI參數為匿名物件            
            var postData = new 
            {
                yourProperty1 = "yourValue1",
                yourProperty2 = "yourValue2"
            };
            //呼叫WebAPI
            var objResult = this._MyWebHelper.PostWebApi<YourClassResult>(url, postData);
            //回傳結果
            return Content(JsonConvert.SerializeObject(objResult, Formatting.Indented), "application/json", Encoding.UTF8);
                     
        }

↓ ASP.NET Framework 4.5+以上 (WebForm 或 ASP.NET MVC )

先自訂義一個自用的Helper類別


using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Web;
using Newtonsoft.Json;//須先透過Nuget加入此參考

namespace YourSystem.Helper
{
    public class MyWebHelper
    {
        
        /// <summary>
        /// content_type 若為"application/x-www-form-urlencoded" 的話，須針對值做Url編碼 Uri.EscapeDataString()
        /// </summary>
        /// <param name="url"></param>
        /// <param name="post_content"></param>
        /// <param name="content_type"></param>
        /// <returns></returns>
        public static string PostWebAPI(string url, string post_content, string content_type = "application/json")
        {
            HttpClient client = new HttpClient();
            //忽略TLS憑證驗證(視需求
            //ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
            //支持TLS連線(視需求
            ServicePointManager.SecurityProtocol = GetSecurityProtocol();
            // 指定 authorization header(若有需要的話)
            //client.DefaultRequestHeaders.Add("authorization", "token {api token}"); 
            // 要 Post傳遞給 WebAPI 的內容
            StringContent content = new StringContent(post_content , Encoding.UTF8, content_type);
            // 發出 http post (json body) 並取得結果
            HttpResponseMessage response = client.PostAsync(url, content).Result;
            // 回應結果字串
            string strResponse = response.Content.ReadAsStringAsync().Result;
            client.Dispose();
            return strResponse;
        }
         private static SecurityProtocolType GetSecurityProtocol()
         {
            int result = 0;
     		foreach (var value in Enum.GetValues(typeof(SecurityProtocolType)))
     		{
         		result += (int)value;
     		}//end foreach
     		return (SecurityProtocolType)result;
         }

 
    }
}

↓ 在WebForm.cs 或 ASP.NET MVC的Controller裡的用法


//要傳遞給WebAPI的參數(匿名物件
var postData =
new   
{
  yourProperty1 = "yourValue1",
  yourProperty2 = "yourValue2"
};  
//呼叫WebApi
string strJson =  MyWebHelper.PostWebApi("yourWebAPIUrl",  JsonConvert.SerializeObject(postData));

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