BackgroundWorker的简单用法

  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.Windows.Forms;
  9 
 10 namespace BackgroundWorkerTest
 11 {
 12     public partial class Form2 : Form
 13     {
 14         /*
 15          * 使用BackgroundWorker的用法很多
 16          * 1.可以直接从左边控件列表中拖一个到界面中
 17          * 2.动态写代码生成，这里我是把它作为成员变量了
 18          * **/
 19         private BackgroundWorker _worker = new BackgroundWorker();
 20 
 21         public Form2()
 22         {
 23             InitializeComponent();
 24 
 25             //设置是否允许报告进度
 26             _worker.WorkerReportsProgress = true;
 27             //设置是否允许取消
 28             _worker.WorkerSupportsCancellation = true;
 29 
 30 
 31             //BackgroundWorker的三个事件之一，异步处理是所要执行的动作
 32             _worker.DoWork += new DoWorkEventHandler(_worker_DoWork);
 33 
 34             //BackgroundWorker的三个事件之二，当进度改变时所要执行的动作
 35             _worker.ProgressChanged += new ProgressChangedEventHandler(_worker_ProgressChanged);
 36 
 37             //BackgroundWorker的三个事件之三，当任务正常完成或手动取消时，所要执行的动作
 38             _worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(_worker_RunWorkerCompleted);
 39         }
 40 
 41 
 42         //运行RunWorkerAsync()时就出发此方法，而且此方法不能与UI有交互，会抛异常
 43         void _worker_DoWork(object sender, DoWorkEventArgs e)
 44         {
 45             //这个类是用来测试报告进度时，除了可以报告进度外，还可以返回一个object的变量
 46             Person tommy = new Person("Tommy.Huang","25","CXY");
 47 
 48             for (int i = 1; i <= 100; i++)
 49             {
 50                 //如果想要实现能够中途取消的功能，就必须在DoWork里面判断是否点击了取消
 51                 //CancellationPending用于判断是运行了CancelAsync()方法
 52                 if (_worker.CancellationPending)
 53                 {
 54                     e.Cancel = true;
 55                     break;
 56                 }
 57                 else
 58                 {
 59                     _worker.ReportProgress(i,tommy);//ReportProgress可以带1个或2个参数，第一个为进度int，第二个为object
 60                     //因为太快，看不到效果，所以让线程每一次暂停半秒
 61                     System.Threading.Thread.Sleep(100);
 62                 }
 63             }
 64         }
 65 
 66         //当进度有所改变时，就会触发该方法，此方法可以与UI交互，所以通常在此方法中处理
 67         void _worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
 68         {
 69             Person p = e.UserState as Person;
 70             this.label1.Text = e.ProgressPercentage.ToString()+"% -"+p.Name;
 71         }
 72 
 73         //当异步线程正常运行结束，或者点击取消时都会执行此方法
 74         void _worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
 75         {
 76             if (e.Cancelled)
 77                 System.Windows.Forms.MessageBox.Show("取消了");
 78             else
 79                 System.Windows.Forms.MessageBox.Show("完成了！");
 80         }
 81 
 82         private void btnStart_Click(object sender, EventArgs e)
 83         {
 84             //需要先判断backgroundWorker是否正在运行
 85             if (!_worker.IsBusy)
 86             {
 87                 //RunWorkerAsync()启动线程
 88                 _worker.RunWorkerAsync();
 89             }
 90         }
 91 
 92         private void btnCancel_Click(object sender, EventArgs e)
 93         {
 94             //先判断backgroundWorker是否支持取消
 95             if (_worker.WorkerSupportsCancellation)
 96             {
 97                 //CancelAsync()取消线程
 98                 _worker.CancelAsync();
 99             }
100         }
101 
102     }
103 }

 1 namespace BackgroundWorkerTest
 2 {
 3     partial class Form2
 4     {
 5         /// <summary>
 6         /// Required designer variable.
 7         /// </summary>
 8         private System.ComponentModel.IContainer components = null;
 9 
10         /// <summary>
11         /// Clean up any resources being used.
12         /// </summary>
13         /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
14         protected override void Dispose(bool disposing)
15         {
16             if (disposing && (components != null))
17             {
18                 components.Dispose();
19             }
20             base.Dispose(disposing);
21         }
22 
23         #region Windows Form Designer generated code
24 
25         /// <summary>
26         /// Required method for Designer support - do not modify
27         /// the contents of this method with the code editor.
28         /// </summary>
29         private void InitializeComponent()
30         {
31             this.btnStart = new System.Windows.Forms.Button();
32             this.btnCancel = new System.Windows.Forms.Button();
33             this.label1 = new System.Windows.Forms.Label();
34             this.SuspendLayout();
35             // 
36             // btnStart
37             // 
38             this.btnStart.Location = new System.Drawing.Point(42, 165);
39             this.btnStart.Name = "btnStart";
40             this.btnStart.Size = new System.Drawing.Size(75, 23);
41             this.btnStart.TabIndex = 0;
42             this.btnStart.Text = "开始";
43             this.btnStart.UseVisualStyleBackColor = true;
44             this.btnStart.Click += new System.EventHandler(this.btnStart_Click);
45             // 
46             // btnCancel
47             // 
48             this.btnCancel.Location = new System.Drawing.Point(249, 165);
49             this.btnCancel.Name = "btnCancel";
50             this.btnCancel.Size = new System.Drawing.Size(75, 23);
51             this.btnCancel.TabIndex = 1;
52             this.btnCancel.Text = "取消";
53             this.btnCancel.UseVisualStyleBackColor = true;
54             this.btnCancel.Click += new System.EventHandler(this.btnCancel_Click);
55             // 
56             // label1
57             // 
58             this.label1.AutoSize = true;
59             this.label1.Location = new System.Drawing.Point(61, 47);
60             this.label1.Name = "label1";
61             this.label1.Size = new System.Drawing.Size(35, 13);
62             this.label1.TabIndex = 2;
63             this.label1.Text = "label1";
64             // 
65             // Form2
66             // 
67             this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
68             this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
69             this.ClientSize = new System.Drawing.Size(388, 230);
70             this.Controls.Add(this.label1);
71             this.Controls.Add(this.btnCancel);
72             this.Controls.Add(this.btnStart);
73             this.Name = "Form2";
74             this.Text = "Form2";
75             this.ResumeLayout(false);
76             this.PerformLayout();
77 
78         }
79 
80         #endregion
81 
82         private System.Windows.Forms.Button btnStart;
83         private System.Windows.Forms.Button btnCancel;
84         private System.Windows.Forms.Label label1;
85     }
86 }