[C#][ASP.NET Web API 2] 調用 Server 功能

2013-11-11

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2020-12-23

[C#.NET][Web API] 調用 Server 功能
紀錄 HttpWebRequest、WebClient、HttpClient 調用 Server 的方式

由於 Web API 所實作出來的服務沒有 metadata，所以我們沒有辦法使用『加入Web參考』讓其他 .NET 開發人員直接引用，我們必須使用 HttpWebRequest、WebClient 、 HttpClient 來存取資料，接下來馬上實作

準備工具 Json.NET

因為 Proxy 的關係我的 NuGet 不能用，所以我以下範例我使用 JavaScriptSerializer

HttpWebRequest、WebClient .NET 2.0 就已經支援

JavaScriptSerializer 則是.NET 3.5 才開始支援

HttpClient 則是.NET4.5 .NET 4.0 才有的產物

本篇則針對 get/post 進行實作

實作內容如下：

HttpWebRequest

GET

POST

WebClient

GET

POST

HttpClient

GET

POST

測試

HttpWebRequest

GET

private void useHttpWebRequest_Get()
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:64365/api/products");
    request.Method = WebRequestMethods.Http.Get;
    request.ContentType = "application/json";

    using (var response = (HttpWebResponse)request.GetResponse())
    {
        if (response.StatusCode == HttpStatusCode.OK)
        {
            using (var stream = response.GetResponseStream())
            using (var reader = new StreamReader(stream))
            {
                var temp = reader.ReadToEnd();

                //TODO:反序列化
                var serializer = new JavaScriptSerializer();
                var list = serializer.Deserialize<List<Product>>(temp);
                this.dataGridView1.DataSource = list;
                this.txtResponse.Text = temp;
            }
        }
        else
        {
            this.dataGridView1.DataSource = null;
        }
    }
}

POST

private void useHttpWebRequest_Post()
{
    //TODO:序列化
    var serializer = new JavaScriptSerializer();
    var jsonText = serializer.Serialize(new Product() { ISBN = "1234" });
    var jsonBytes = Encoding.UTF8.GetBytes(jsonText);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://localhost:64365/api/products");
    request.Method = WebRequestMethods.Http.Post;
    request.ContentType = "application/json";
    request.ContentLength = jsonBytes.Length;

    using (var requestStream = request.GetRequestStream())
    {
        requestStream.Write(jsonBytes, 0, jsonBytes.Length);
        requestStream.Flush();
    }

    using (var response = (HttpWebResponse)request.GetResponse())
    {
        using (var stream = response.GetResponseStream())
        using (var reader = new StreamReader(stream))
        {
            var result = reader.ReadToEnd();
            MessageBox.Show(result);
        }
    }
}

WebClient

GET

private void useWebClient_Get()
{
    WebClient client = new WebClient();
    client.Encoding = Encoding.UTF8; client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
    var body = client.DownloadString("http://localhost:64365/api/products");    
    //TODO:反序列化     
    var serializer = new JavaScriptSerializer();     
    var list = serializer.Deserialize<List<Product>>(body);  
    this.dataGridView1.DataSource = list;     
    this.txtResponse.Text = body;
}

POST

private void useWebClient_Post()
{
    //TODO:序列化
    var serializer = new JavaScriptSerializer();
    var product = new Product() { ISBN = "222" };
    var jsonText = serializer.Serialize(product);

    WebClient client = new WebClient();
    client.Encoding = Encoding.UTF8;
    client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
    var response = client.UploadData("http://localhost:64365/api/products", "POST", Encoding.UTF8.GetBytes(jsonText));
    MessageBox.Show(Encoding.UTF8.GetString(response));
}

HttpClient

HttpClient 使用 TAP 非同步模組，回傳 Task<HttpResponseMessage> 詳細用法請參考 http://www.dotblogs.com.tw/yc421206/category/9208.aspx

GET

private void useHttpClient_Get()
{
    var client = new HttpClient();
    client.BaseAddress = new Uri("http://localhost:64365/");
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var response = client.GetAsync("api/products").Result;
    var body = response.Content.ReadAsStringAsync().Result;

    //TODO:反序列化
    var serializer = new JavaScriptSerializer();
    var list = serializer.Deserialize<List<Product>>(body);
    this.dataGridView1.DataSource = list;
    this.txtResponse.Text = body;
}

POST

private void useHttpClient_Post()
{
    var serializer = new JavaScriptSerializer();
    var product    = new Product {ISBN = "1234"};
    var jsonText   = serializer.Serialize(product);
    var client     = new HttpClient();
    client.BaseAddress = new Uri("http://localhost:64365/");
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    StringContent content      = new StringContent(jsonText, Encoding.UTF8, "application/json");
    var           response     = client.PostAsync("api/products", content).Result;
    string        responseBody = response.Content.ReadAsStringAsync().Result;
    MessageBox.Show(responseBody);
}

在.NET4.5 4.0 裡新增了 System.Net.Http.HttpContentExtensions 它主要是增加一些擴充功能，比如 PostAsJsonAsync

這可以省掉序列化的動作，不過調用 PostAsJsonAsync 處理 json 序列化資料，不過也是需要 Json.NET，參考：http://www.asp.net/web-api/overview/web-api-clients/calling-a-web-api-from-a-net-client