.Net 简单的异步操作及实践

C# 5.0后，我们可以简单的使用 async/await 关键字 进行实现异步操作

同步操作：

public string Test()
{
    DateTime startTime = DateTime.Now;

    string api_1s = "http://localhost:58575/home/Api_1s";
    string api_3s = "http://localhost:58575/home/Api_3s";
    string api_5s = "http://localhost:58575/home/Api_5s";

    GetRequest(api_1s);
    GetRequest(api_3s);
    GetRequest(api_5s);

    DateTime endTime = DateTime.Now; 
    return "响应时间：" + (endTime - startTime).TotalSeconds.ToString() + "s"; //9.1s
}

异步操作：

using System.Threading.Tasks;

public async Task< string > TestAsync()
{
    DateTime startTime = DateTime.Now;

    string api_1s = "http://localhost:58575/home/Api_1s";
    string api_3s = "http://localhost:58575/home/Api_3s";
    string api_5s = "http://localhost:58575/home/Api_5s";

    List tasks = new List();

    var t1 = GetRequestAsync(api_1s);
    var t2 = GetRequestAsync(api_3s);
    var t3 = GetRequestAsync(api_5s);

    tasks.Add(t1);
    tasks.Add(t2);
    tasks.Add(t3);
    await Task.WhenAll(tasks);

    DateTime endTime = DateTime.Now;
    return "响应时间：" + (endTime - startTime).TotalSeconds.ToString() + "s";//5.1s
}

其中请求方法如下：

public async Task GetRequestAsync(string url)
{
    WebClient MyWebClient = new WebClient();
    MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据
    Byte[] pageData = await MyWebClient.DownloadDataTaskAsync(url); //从指定网站下载数据 
    return Encoding.UTF8.GetString(pageData);
}


public string GetRequest(string url)
{
    WebClient MyWebClient = new WebClient();
    MyWebClient.Credentials = CredentialCache.DefaultCredentials;
    Byte[] pageData = MyWebClient.DownloadData(url);
    return Encoding.UTF8.GetString(pageData);
}