c# - 对 .Net 任务进行排序

Question

我有几个 Task对象，例如 Task<int> , Task<string> , Task<double> ，我想按顺序运行。也就是说，随着每个任务完成，下一个任务会自动启动。每个任务都依赖于前一个任务的输出。

我该怎么做呢？ myTask.ContinueWith(...) 重载都假定一个委托(delegate)参数。但是 Task 不是委托(delegate)。

Answer 1

你可以这样做:

var t1 = new Task(() => Console.WriteLine("Completed t1"));
var t2 = new Task(() => Console.WriteLine("Completed t2"));
var t3 = new Task(() => Console.WriteLine("Completed t3"));

t1.ContinueWith(t => t2.RunSynchronously())
    .ContinueWith(t => t3.RunSynchronously());

t1.Start();

如果您不关心任务的结果，上面的示例仅适用。但是，如果您(如您的编辑状态)需要将每个任务的结果传递给下一个任务，那么您可以执行以下操作:

var t1 = new Task(() => Console.WriteLine("Completed t1"));
var t2 = new Task(() => Console.WriteLine("Completed t2"));
var t3 = new Task(() => Console.WriteLine("Completed t3"));

t1.ContinueWith(task1 =>
{
    Console.WriteLine(task1.Result);

    t2.ContinueWith(task2 =>
    {
        Console.WriteLine("{0} | {1}", task1.Result, task2.Result);

        t3.ContinueWith(task3 =>
        {
            Console.WriteLine("{0} | {1} | {2}", 
                task1.Result, task2.Result, task3.Result);
        });

        t3.Start();
    });

    t2.Start();
});

t1.Start();

/* OUTPUT:
Completed t1
Completed t1 | Completed t2
Completed t1 | Completed t2 | Completed t3 */