Async HTTP使用Async CTP在单个函数中发布数据

Question

我正在尝试使用Async CTP来构建运行异步并返回值的单个函数.

这是我的示例代码.我不知道为什么它不会在返回时填充"resp"变量.

public async Task<string> sendRequest(string url, string postdata)
{
    WebClient client = new WebClient();
    byte[] data = Encoding.UTF8.GetBytes(postdata);
    Uri uri = new Uri(url);
    client.UploadDataAsync(uri,"POST", data);
    string resp = "";
    await TaskEx.Run(()=>
    client.UploadDataCompleted += (e, s) =>
    {
        resp = System.Text.Encoding.UTF8.GetString(s.Result);
    });
    return resp;
}

我也尝试了这个,但程序冻结了(不做了一段时间).也许任何纠正都可以帮助.

public async Task<string> sendRequest(string url, string postdata)
{
    string resp = "";
    WebClient client = new WebClient();
    byte[] data = Encoding.UTF8.GetBytes(postdata);
    Uri uri = new Uri(url);
    data = await TaskEx.Run(()=>client.UploadData(uri,"POST", data));

    return System.Text.Encoding.UTF8.GetString(data);
}

Answer 1

相反,您可以使用UploadDataTaskAsync扩展方法(CTP的一部分),而不必自己编写管道代码:

public async Task<string> sendRequest(string url, string postdata)
{
    WebClient client = new WebClient();
    byte[] data = Encoding.UTF8.GetBytes(postdata);
    Uri uri = new Uri(url);
    resp = System.Text.Encoding.UTF8.GetString(await client.UploadDataTaskAsync(uri,"POST", data));
    return resp;
}

该扩展方法的实现正确处理事件订阅,并确保在事件实际触发时完成任务.