一、简介
Task.WaitAll：等待所有提供的 Task 对象完成执行过程。
Task.WaitAny：等待提供的任一 Task 对象完成执行过程。
二、代码案例
Task.WaitAll
代码：
class Program
{
public class DownLoadTest
{
Stopwatch watch = new Stopwatch();
public DownLoadTest()
{
watch.Start();
}
public async Task DoRunTaskAsync(string url, CancellationToken ct)
{
if (ct.IsCancellationRequested)
{
Console.WriteLine(string.Format("取消{0}的運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
return;
}
Console.WriteLine(string.Format("下載{0}開始運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
WebClient wc = new WebClient();
await Task.Run(() =>
{
var task = wc.DownloadStringTaskAsync(url);
while (!task.IsCompleted)
{
if (ct.IsCancellationRequested)
{
Console.WriteLine(string.Format("取消{0}的運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
return;
}
}
if (task.IsCompleted)
Console.WriteLine(string.Format("下載{0}運行結束 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
});
}
}
static void Main(string[] args)
{
DownLoadTest dwtest = new DownLoadTest();
CancellationTokenSource cts = new CancellationTokenSource();
CancellationToken token = cts.Token;
var task1 = dwtest.DoRunTaskAsync("https://www.baidu.com/", token);
var task2 = dwtest.DoRunTaskAsync("https://www.taobao.com/", token);
var task3 = dwtest.DoRunTaskAsync("https://www.cnblogs.com/", token);
Task[] tasks = new Task[] { task1, task2, task3 };
Console.WriteLine("task.Result等待結果打印");
Task.WaitAll(tasks, 10000);
cts.Cancel();//超过10s时间取消运行
Console.WriteLine(task1.Status);
Console.WriteLine(task2.Status);
Console.WriteLine(task3.Status);
Console.WriteLine(string.Format("主線程運行結束"));
Console.ReadKey();
}
}运行结果：
通过运行结果可以看出，可以看到Task.WaitAll(tasks)在等待超时的时间内，同步等待了所有的任务完成。
Task.WaitAny
代码：
class Program
{
public class DownLoadTest
{
Stopwatch watch = new Stopwatch();
public DownLoadTest()
{
watch.Start();
}
public async Task DoRunTaskAsync(string url, CancellationToken ct)
{
if (ct.IsCancellationRequested)
{
Console.WriteLine(string.Format("取消{0}的運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
return;
}
Console.WriteLine(string.Format("下載{0}開始運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
WebClient wc = new WebClient();
await Task.Run(() =>
{
var task = wc.DownloadStringTaskAsync(url);
while (!task.IsCompleted)
{
if (ct.IsCancellationRequested)
{
Console.WriteLine(string.Format("取消{0}的運行 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
return;
}
}
if (task.IsCompleted)
Console.WriteLine(string.Format("下載{0}運行結束 :{1,4:N0}ms", url, watch.Elapsed.TotalMilliseconds));
});
}
}
static void Main(string[] args)
{
DownLoadTest dwtest = new DownLoadTest();
CancellationTokenSource cts = new CancellationTokenSource();
CancellationToken token = cts.Token;
var task1 = dwtest.DoRunTaskAsync("https://www.baidu.com/", token);
var task2 = dwtest.DoRunTaskAsync("https://www.taobao.com/", token);
var task3 = dwtest.DoRunTaskAsync("https://www.cnblogs.com/", token);
Task[] tasks = new Task[] { task1, task2, task3 };
Console.WriteLine("task.Result等待結果打印");
Task.WaitAny(tasks, 4000);
cts.Cancel();//超过4s时间取消运行
Console.WriteLine(task1.Status);
Console.WriteLine(task2.Status);
Console.WriteLine(task3.Status);
Console.WriteLine(string.Format("主線程運行結束"));
Console.ReadKey();
}
}运行结果：
通过运行结果截图可以看出，可以看到，Task.WhenAny(tasks)至少等待了一个任务的完成。这里https://www.baidu.com/先下载完，就直接终止等待 。
三、总结
Task.WaitAll阻止当前线程，直到所有其他任务完成执行为止。Task.WaitAny阻止当前线程，至少等待一个任务完成执行为止。如果等待时长设置较长，上述案例结果会一样。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程网。
