/* * 演示用 BackgroundWorker 在后台线程上执行耗时的操作 * 按“开始”键,开始在后台线程执行耗时操作,并向UI线程汇报执行进度 * 按“取消”键,终止后台线程 * BackgroundWorker 调用 UI 线程时会自动做线程同步 */ using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
namespace Silverlight20.Thread
{
public partial
class BackgroundWorker : UserControl
{
// BackgroundWorker - 用于在单独的线程上运行操作。例如可以在非UI线程上运行耗时操作,以避免UI停止响应 System.ComponentModel.BackgroundWorker _backgroundWorker;
public BackgroundWorker()
{
InitializeComponent();
BackgroundWorkerDemo();
}
void BackgroundWorkerDemo()
{
/* * WorkerSupportsCancellation - 是否支持在其他线程中取消该线程的操作 * WorkerReportsProgress - 是否可以报告操作进度 * ProgressChanged - 报告操作进度时触发的事件 * DoWork - BackgroundWorker 调用 RunWorkerAsync() 方法时触发的事件。在此执行具体操作 * RunWorkerCompleted - 操作完成/取消/出错时触发的事件 */ _backgroundWorker =
new System.ComponentModel.BackgroundWorker();
_backgroundWorker.WorkerSupportsCancellation =
true;
_backgroundWorker.WorkerReportsProgress =
true;
_backgroundWorker.ProgressChanged +=
new System.ComponentModel.ProgressChangedEventHandler(_backgroundWorker_ProgressChanged);
_backgroundWorker.DoWork +=
new System.ComponentModel.DoWorkEventHandler(_backgroundWorker_DoWork);
_backgroundWorker.RunWorkerCompleted +=
new System.ComponentModel.RunWorkerCompletedEventHandler(_backgroundWorker_RunWorkerCompleted);
}
private void btnStart_Click(
object sender, RoutedEventArgs e)
{
// IsBusy - 指定的 BackgroundWorker 是否正在后台操作 // RunWorkerAsync(object argument) - 开始在后台线程执行指定的操作 // object argument - 需要传递到 DoWork 的参数 if (!_backgroundWorker.IsBusy)
_backgroundWorker.RunWorkerAsync(
"需要传递的参数");
}
private void btnCancel_Click(
object sender, RoutedEventArgs e)
{
// CancelAsync() - 取消 BackgroundWorker 正在执行的后台操作 if (_backgroundWorker.WorkerSupportsCancellation)
_backgroundWorker.CancelAsync();
}
void _backgroundWorker_DoWork(
object sender, System.ComponentModel.DoWorkEventArgs e)
{
/* * DoWorkEventArgs.Argument - RunWorkerAsync(object argument)传递过来的参数 * DoWorkEventArgs.Cancel - 取消操作 * DoWorkEventArgs.Result - 操作的结果。将传递到 RunWorkerCompleted 所指定的方法 * BackgroundWorker.ReportProgress(int percentProgress, object userState) - 向 ProgressChanged 汇报操作的完成进度 * int percentProgress - 操作完成的百分比 1% - 100% * object userState - 传递到 ProgressChanged 的参数 */ for (
int i = 0; i < 10; i++)
{
if ((_backgroundWorker.CancellationPending ==
true))
{
e.Cancel =
true;
break;
}
else {
System.Threading.Thread.Sleep(1000);
_backgroundWorker.ReportProgress((i + 1) * 10, i);
}
}
e.Result =
"操作已完成";
}
void _backgroundWorker_ProgressChanged(
object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
// ProgressChangedEventArgs.ProgressPercentage - ReportProgress 传递过来的操作完成的百分比 // ProgressChangedEventArgs.UserState - ReportProgress 传递过来的参数 txtProgress.Text =
string.Format(
"完成进度:{0}%;参数:{1}",
e.ProgressPercentage,
e.UserState);
}
void _backgroundWorker_RunWorkerCompleted(
object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
{
/* * RunWorkerCompletedEventArgs.Error - DoWork 时产生的错误 * RunWorkerCompletedEventArgs.Cancelled - 后台操作是否已被取消 * RunWorkerCompletedEventArgs.Result - DoWork 的结果 */ if (e.Error !=
null)
{
txtMsg.Text += e.Error.ToString() +
"\r\n";
}
else if (e.Cancelled)
{
txtMsg.Text +=
"操作被取消\r\n";
}
else {
txtMsg.Text += e.Result.ToString() +
"\r\n";
}
}
}
}