如何从“第三方”库中的方法返回另一个值？

Question

Task<string>[] tableOfWebClientTasks = new Task<string>[taskCount];

for (int i = 0; i < taskCount; i++)
{
    tableOfWebClientTasks[i] = new WebClient().DownloadStringTask(allUrls[count - i - 1]);
}

Task.Factory.ContinueWhenAll(tableOfWebClientTasks, tasks =>
{
    Parallel.ForEach(tasks, task =>
    {
        //Here I have result from each task.
        //But information which url is executed on this task, is lost.
    });
});

例如，我可以创建类（具有两个公共属性，一个用于任务，第二个用于 url）并返回实例。但是这个方法我连接了其他方法。

你有解决这个问题的办法吗？

Answer 1

如果您希望能够将您的任务与创建它们的 url 相关联，您可以使用字典进行映射：

Task<string>[] tableOfWebClientTasks = new Task<string>[taskCount];
var taskIdToUrl = new Dictionary<int,string>();

for (int i = 0; i < taskCount; i++)
{
    var url = allUrls[count - i - 1];
    var task = new WebClient().DownloadStringTask(url);
    tableOfWebClientTasks[i] = task;
    taskIdToUrl.Add(task.Id, url);
}

TaskFactory.ContinueWhenAll(tableOfWebClientTasks, tasks =>
{
    Parallel.ForEach(tasks, task =>
    {
        // To get the url just do:
        var url = taskIdToUrl[task.Id];
    });
});