c# - 如何在 C# 中向 Web 服务并行发出多个请求

Question

我需要如下调用 3 个 WCF 服务，

var client = new WebClient();
    client.Headers[HttpRequestHeader.ContentType] = "application/json";
    var resultJson1 = client.UploadString("http://localhost:45868/Product/GetAvailableProductsByContact",
                                         jsonser1);
var resultJson2= client.UploadString("http://localhost:45868/Product/GetMemberProductsByContact",
                                         jsonser2);

var resultJson3= client.UploadString("http://localhost:45868/Product/GetCoachProductsByContact",
                                         jsonser3);

这需要花费大量时间来获取结果并显示在页面上。谁能帮助我如何并行执行它们？

Answer 1

您可以使用 task parallelism library :

Task<string>[] taskArray = new Task<string>[]
    {
        Task.Factory.StartNew(() => {
            var client = new WebClient();
            client.Headers[HttpRequestHeader.ContentType] = "application/json";
            var json = client.UploadString("http://localhost:45868/Product/GetAvailableProductsByContact",
                                     jsonser1);
            return json;
        }),
        Task.Factory.StartNew(() => {
            var client = new WebClient();
            client.Headers[HttpRequestHeader.ContentType] = "application/json";
            var json = client.UploadString("http://localhost:45868/Product/GetMemberProductsByContact",
                                     jsonser2);
            return json;
        }),
        Task.Factory.StartNew(() => {
            var client = new WebClient();
            client.Headers[HttpRequestHeader.ContentType] = "application/json";
            var json = client.UploadString("http://localhost:45868/Product/GetCoachProductsByContact",
                                     jsonser3);
            return json;
        }),
    };

// the request for .Result is blocking and waits until each task
// is completed before continuing; however, they should also all
// run in parallel instead of sequentially.
var resultJson1 = taskArray[0].Result;
var resultJson2 = taskArray[1].Result;
var resultJson3 = taskArray[2].Result;

或者，由于您的请求都非常相似，仅 url 和上传字符串不同，您可以使用 LINQ AsParallel 数组处理:

var requests = new [] {
    new { Url = "http://localhost:45868/Product/GetAvailableProductsByContact", Input = jsonser1 },
    new { Url = "http://localhost:45868/Product/GetMemberProductsByContact", Input = jsonser2 },
    new { Url = "http://localhost:45868/Product/GetCoachProductsByContact", Input = jsonser3 },
};
var result = requests.AsParallel().Select(req => {
    var client = new WebClient();
    client.Headers[HttpRequestHeader.ContentType] = "application/json";
    var json = client.UploadString(req.Url, req.Input);
    return json;
}).ToArray();

// when above code has finished running, all tasks are completed
var resultJson1 = result[0];
var resultJson2 = result[1];
var resultJson3 = result[2];