C# Task任务队列
新建一个Winfrom项目，加入下面代码：
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace 线程2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
Task task1 = new Task(() =>
{
Thread.Sleep(400);
Console.WriteLine("task1");
});
Task task2 = new Task(() =>
{
Thread.Sleep(300);
Console.WriteLine("task2");
});
Task task3 = new Task(() =>
{
Thread.Sleep(200);
Console.WriteLine("task3");
});
Task task4 = new Task(() =>
{
Thread.Sleep(100);
Console.WriteLine("task4");
});
task1.Start();
task2.Start();
task3.Start();
task4.Start();
}
}
}
运行：
由于延时不同，最先执行的Task1，反而最后一个执行完，那么如果要求从任务1，一直执行到任务4，怎么写呢？
代码：
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace 线程2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private List TaskList = new List();
private void Form1_Load(object sender, EventArgs e)
{
Task task1 = new Task(() =>
{
Thread.Sleep(400);
Console.WriteLine("task1");
});
Task task2 = new Task(() =>
{
Thread.Sleep(300);
Console.WriteLine("task2");
});
Task task3 = new Task(() =>
{
Thread.Sleep(200);
Console.WriteLine("task3");
});
Task task4 = new Task(() =>
{
Thread.Sleep(100);
Console.WriteLine("task4");
});
TaskList.Add(task1);
TaskList.Add(task2);
TaskList.Add(task3);
TaskList.Add(task4);
foreach (Task task in TaskList)
{
task.Start();
task.Wait();
}
}
}
}
运行：
用上面的方法虽然有效，但会阻塞主线程，导致winfrom界面卡住，无法操作，下面就用异步的方法解决问题
代码：
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace 线程2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private List TaskList = new List();
private void Form1_Load(object sender, EventArgs e)
{
}
private void Button_Calculate_Click(object sender, EventArgs e)
{
Task task1 = new Task(async () =>
{
await Task.Delay(TimeSpan.FromSeconds(4));
Console.WriteLine("task1");
});
Task task2 = new Task(async () =>
{
await Task.Delay(TimeSpan.FromSeconds(3));
Console.WriteLine("task2");
});
Task task3 = new Task(async () =>
{
await Task.Delay(TimeSpan.FromSeconds(2));
Console.WriteLine("task3");
});
Task task4 = new Task(async () =>
{
await Task.Delay(TimeSpan.FromSeconds(1));
Console.WriteLine("task4");
});
TaskList.Add(task1);
TaskList.Add(task2);
TaskList.Add(task3);
TaskList.Add(task4);
foreach (Task task in TaskList)
{
task.Start();
task.Wait();
}
}
}
}
运行：
用异步方式虽然界面不会卡住，但另一个问题来了，task.wait()方法似乎没有效果。里面的任务队列依然没有按顺序来执行。
经过一段时间的研究，后面我终于找到方法了，用下面的方法既不会卡住UI，也会按照队列来执行，虽然写法不是特别好，读者可以按下面方法自己封装了。
private void Test()
{
Task.Run(() =>
{
Task t1 = new Task(() => {
Thread.Sleep(2000);
Console.WriteLine("t1");
num = 1;
});
t1.Start();
t1.Wait();
Task t2 = new Task(() => {
Thread.Sleep(1000);
Console.WriteLine("t2");
num = 3;
});
t2.Start();
t2.Wait();
Console.WriteLine("线程执行完毕");
});
}运行：
也可以这样写：
private async void Test()
{
await Task.Run(async () =>
{
await Task.Delay(4000);
Trace.WriteLine("第1个线程执行");
});
await Task.Run(async () =>
{
await Task.Delay(3000);
Trace.WriteLine("第2个线程执行");
});
await Task.Run(async () =>
{
await Task.Delay(2000);
Trace.WriteLine("第3个线程执行");
});
}运行：
对现有代码进行封装:
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespace Utils
{
public class TaskQueue
{
///
/// 任务列表
///
private List TaskList = null;
///
/// 是否在执行任务中
///
private bool isPerformTask = false;
///
/// 执行完任务的回调
///
public Action CallBack = null;
private static TaskQueue _instance = null;
public static TaskQueue Instance
{
get
{
if (_instance == null)
_instance = new TaskQueue();
return _instance;
}
}
///
/// 添加任务
///
///
public void AddTask(Task task)
{
if (isPerformTask)
{
Console.WriteLine("[TaskQueue]任务正在执行中，此时不能做赋值操作");
return;
}
if (task != null)
{
TaskList.Add(task);
}
}
///
/// 执行任务
///
public void PerformTask()
{
if (isPerformTask)
{
Console.WriteLine("[TaskQueue]任务正在执行中，不可重复调用");
return;
}
if (TaskList == null || TaskList.Count == 0)
{
Console.WriteLine("[TaskQueue]任务列表为空");
return;
}
Task.Run(() =>
{
isPerformTask = true;
foreach (Task item in TaskList)
{
item.Start();
item.Wait();
}
TaskList.Clear();
isPerformTask = false;
if (CallBack != null) CallBack();
});
}
private TaskQueue()
{
TaskList = new List();
}
}
}
调用：
Task task1 = new Task(() =>
{
Thread.Sleep(1000);
Console.WriteLine("t1");
});
Task task2 = new Task(() =>
{
Thread.Sleep(2000);
Console.WriteLine("t2");
});
Task task3 = new Task(() =>
{
Console.WriteLine("t3");
});
Action callback = () =>
{
Console.WriteLine("所有任务执行完成");
};
TaskQueue.Instance.AddTask(task1);
TaskQueue.Instance.AddTask(task2);
TaskQueue.Instance.AddTask(task3);
TaskQueue.Instance.CallBack = callback;
TaskQueue.Instance.PerformTask();运行：
如果你这个帖子对你有用，欢迎给我点赞 + 留言，谢谢
end