一個簡單的例子看明白 async await Task

測試代碼：

  1 using System;
  2 using System.Collections.Generic;
  3 using System.ComponentModel;
  4 using System.Data;
  5 using System.Drawing;
  6 using System.Linq;
  7 using System.Text;
  8 using System.Threading;
  9 using System.Threading.Tasks;
 10 using System.Windows.Forms;
 11 using Utils;
 12 
 13 namespace test
 14 {
 15     public partial class Form1 : Form
 16     {
 17         public Form1()
 18         {
 19             InitializeComponent();
 20         }
 21 
 22         private void Form1_Load(object sender, EventArgs e)
 23         {
 24 
 25         }
 26 
 27         /// <summary>
 28         /// 執行任務
 29         /// </summary>
 30         public string DoWork(string str)
 31         {
 32             Thread.Sleep(3000); //模擬延遲 比如網路請求 用了3000毫秒
 33             return "輸出：" + str;
 34         }
 35 
 36         /// <summary>
 37         /// 執行任務
 38         /// </summary>
 39         public Task<string> DoWorkByTask(string str)
 40         {
 41             return Task.Run(() =>
 42             {
 43                 Thread.Sleep(3000); //模擬延遲 比如網路請求 用了3000毫秒
 44                 return "輸出：" + str;
 45             });
 46         }
 47 
 48         /// <summary>
 49         /// 測試1
 50         /// </summary>
 51         private async void button1_Click(object sender, EventArgs e)
 52         {
 53             LogTimeUtil logTime = new LogTimeUtil();
 54 
 55             var t1 = DoWorkByTask("測試值1");
 56 
 57             var t2 = DoWorkByTask("測試值2");
 58 
 59             string r1 = await t1;
 60 
 61             textBox1.AppendText(r1 + "\r\n");
 62 
 63             string r2 = await t2;
 64 
 65             textBox1.AppendText(r2 + "\r\n");
 66 
 67             logTime.LogTime("耗時", textBox1);
 68         }
 69 
 70         /// <summary>
 71         /// 測試2 
 72         /// 
 73         /// 等效於 測試1
 74         /// </summary>
 75         private void button2_Click(object sender, EventArgs e)
 76         {
 77             Task.Run(() => //如果不加Task.Run，界面會卡
 78             {
 79                 LogTimeUtil logTime = new LogTimeUtil();
 80 
 81                 Task<string> t1 = Task.Run<string>(() => { return DoWork("測試值1"); });
 82                 Task<string> t2 = Task.Run<string>(() => { return DoWork("測試值2"); });
 83 
 84                 Task.WaitAll(t1, t2);
 85 
 86                 this.Invoke(new Action(() => //線程中修改控制項數據要使用Invoke
 87                 {
 88                     textBox1.AppendText(t1.Result + "\r\n");
 89                     textBox1.AppendText(t2.Result + "\r\n");
 90                 }));
 91 
 92                 logTime.LogTime("耗時", textBox1);
 93             });
 94         }
 95 
 96         /// <summary>
 97         /// 測試3 
 98         /// </summary>
 99         private async void button3_Click(object sender, EventArgs e)
100         {
101             LogTimeUtil logTime = new LogTimeUtil();
102 
103             var r1 = await DoWorkByTask("測試值1");
104 
105             textBox1.AppendText(r1 + "\r\n");
106 
107             var r2 = await DoWorkByTask("測試值2");
108 
109             textBox1.AppendText(r2 + "\r\n");
110 
111             logTime.LogTime("耗時", textBox1);
112         }
113 
114         /// <summary>
115         /// 測試4
116         /// 
117         /// 等效於 測試3
118         /// </summary>
119         private void button4_Click(object sender, EventArgs e)
120         {
121             Task.Run(() => //如果不加Task.Run，界面會卡
122             {
123                 LogTimeUtil logTime = new LogTimeUtil();
124 
125                 Task<string> t1 = Task.Run<string>(() => { return DoWork("測試值1"); });
126                 t1.Wait();
127                 this.Invoke(new Action(() => //線程中修改控制項數據要使用Invoke
128                 {
129                     textBox1.AppendText(t1.Result + "\r\n");
130                 }));
131 
132                 Task<string> t2 = Task.Run<string>(() => { return DoWork("測試值2"); });
133                 t2.Wait();
134                 this.Invoke(new Action(() => //線程中修改控制項數據要使用Invoke
135                 {
136                     textBox1.AppendText(t2.Result + "\r\n");
137                 }));
138 
139                 logTime.LogTime("耗時", textBox1);
140             });
141         }
142 
143     }
144 }

測試輸出：

附 LogTimeUtil.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Utils
{
    /// <summary>
    /// 記錄耗時
    /// </summary>
    public class LogTimeUtil
    {
        private DateTime _lastTime;

        public LogTimeUtil()
        {
            _lastTime = DateTime.Now;
        }

        /// <summary>
        /// 記錄耗時
        /// </summary>
        public void LogTime(string msg)
        {
            double d = DateTime.Now.Subtract(_lastTime).TotalSeconds;
            LogUtil.Log(msg + "，耗時：" + d.ToString("0.000") + " 秒");
        }

        /// <summary>
        /// 記錄耗時
        /// </summary>
        public void LogTime(string msg, TextBox txt)
        {
            double d = DateTime.Now.Subtract(_lastTime).TotalSeconds;
            msg = msg + "，耗時：" + d.ToString("0.000") + " 秒\r\n";
            if (txt.InvokeRequired)
            {
                txt.Invoke(new Action(() =>
                {
                    txt.AppendText(msg);
                }));
            }
            else
            {
                txt.AppendText(msg);
            }
        }
    }
}