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稳扎稳打Silverlight(25) - 2.0线程之Thread, Timer, BackgroundWorker, ThreadPool


作者:webabcd


介绍
Silverlight 2.0 使用Thread, Timer, BackgroundWorker, ThreadPool来实现多线程开发
    Thread - 用于线程的创建和控制的类
    Timer - 用于以指定的时间间隔执行指定的方法的类
    BackgroundWorker - 用于在单独的线程上运行操作
    ThreadPool - 线程池的管理类


在线DEMO
http://webabcd.blog.51cto.com/1787395/342779


示例
1、Thread.xaml
<UserControl x:Class="Silverlight20.Thread.Thread"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <StackPanel HorizontalAlignment="Left" Margin="5">
        
                <TextBlock x:Name="txtMsg" />
        
        </StackPanel>
</UserControl>
 
Thread.xaml.cs
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 Thread : UserControl
        {
                string result = "";

                public Thread()
                {
                        InitializeComponent();

                        Demo();
                }

                void Demo()
                {
                        /*
                         * Thread - 用于线程的创建和控制的类
                         *         Name - 线程名称
                         *         IsBackground - 是否是后台线程(对于Silverlight来说,是否是后台线程没区别)
                         *         Start(object parameter) - 启动后台线程
                         *                 object parameter - 为后台线程传递的参数
                         *         IsAlive - 线程是否在执行中
                         *         ManagedThreadId - 当前托管线程的唯一标识符
                         *         ThreadState - 指定线程的状态 [System.Threading.ThreadState枚举]
                         *         Abort() - 终止线程
                         */


                        // DoWork 是后台线程所执行的方法(此处省略掉了委托类型)
                        // ThreadStart 委托不可以带参数, ParameterizedThreadStart 委托可以带参数
                        System.Threading.Thread thread = new System.Threading.Thread(DoWork);
                        thread.Name = "ThreadDemo";
                        thread.IsBackground = true;
                        thread.Start(1000);

                        result += thread.IsAlive + "\r\n";
                        result += thread.ManagedThreadId + "\r\n";
                        result += thread.Name + "\r\n";
                        result += thread.ThreadState + "\r\n";

                        // thread.Join(); 阻塞调用线程(本例为主线程),直到指定线程(本例为thread)执行完毕为止

                        // 阻塞调用线程(本例为主线程)
                        // 如果指定线程执行完毕则继续(本例为thread执行完毕则继续)
                        // 如果指定线程运行的时间超过指定时间则继续(本例为thread执行时间如果超过5秒则继续)
                        // 返回值为在指定时间内指定线程是否执行完毕(本例中thread的执行时间为1秒,所以会返回true)
                        if (thread.Join(5000))    
                        {
                                result += "指定线程在5秒内执行完毕\r\n";
                        }

                        txtMsg.Text = result;
                }

                void DoWork(object sleepMillisecond)
                {
                        System.Threading.Thread.Sleep((int)sleepMillisecond);

                        result += "新开线程执行完毕\r\n";
                }
        }
}
 
2、Timer.xaml
<UserControl x:Class="Silverlight20.Thread.Timer"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <StackPanel HorizontalAlignment="Left" Margin="5">
        
                <TextBlock x:Name="txtMsg" />
        
        </StackPanel>
</UserControl>
 
Timer.xaml.cs
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 Timer : UserControl
        {
                System.Threading.SynchronizationContext _syncContext;
                // Timer - 用于以指定的时间间隔执行指定的方法的类
                System.Threading.Timer _timer;
                private int _flag = 0;

                public Timer()
                {
                        InitializeComponent();

                        // UI 线程
                        _syncContext = System.Threading.SynchronizationContext.Current;

                        Demo();
                }

                void Demo()
                {
                        // 输出当前时间
                        txtMsg.Text = DateTime.Now.ToString() + "\r\n";

                        // 第一个参数:定时器需要调用的方法
                        // 第二个参数:传给需要调用的方法的参数
                        // 第三个参数:此时间后启动定时器
                        // 第四个参数:调用指定方法的间隔时间(System.Threading.Timeout.Infinite 为无穷大)
                        _timer = new System.Threading.Timer(MyTimerCallback, "webabcd", 3000, 1000);
                }

                private void MyTimerCallback(object state)
                {
                        string result = string.Format("{0} - {1}\r\n", DateTime.Now.ToString(), (string)state);

                        // 调用 UI 线程。不会做自动线程同步
                        _syncContext.Post(delegate { txtMsg.Text += result; }, null);    

                        _flag++;
                        if (_flag == 5)
                                _timer.Change(5000, 500); // 执行5次后,计时器重置为5秒后启动,每5毫秒的间隔时间执行一次指定的方法
                        else if (_flag == 10)
                                _timer.Dispose(); // 执行10次后,释放计时器所使用的全部资源
                }
        }
}
 
 
3、BackgroundWorker.xaml
<UserControl x:Class="Silverlight20.Thread.BackgroundWorker"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <StackPanel HorizontalAlignment="Left" Margin="5">

                <StackPanel Orientation="Horizontal" Margin="5">
                        <Button x:Name="btnStart" Content="开始" Margin="5" Click="btnStart_Click" />
                        <Button x:Name="btnCancel" Content="取消" Margin="5" Click="btnCancel_Click" />
                </StackPanel>
                
                <StackPanel Margin="5">
                        <TextBlock x:Name="txtProgress" Margin="5" />
                        <TextBlock x:Name="txtMsg" Margin="5" />
                </StackPanel>

        </StackPanel>    
</UserControl>
 
BackgroundWorker.xaml.cs
/*
* 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";
                        }
                }
        }
}
 
 
4、ThreadPool.xaml
<UserControl x:Class="Silverlight20.Thread.ThreadPool"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <StackPanel HorizontalAlignment="Left" Margin="5">

                <TextBlock x:Name="txtMsgQueueUserWorkItem" Text="click here" MouseLeftButtonDown="txtMsgQueueUserWorkItem_MouseLeftButtonDown" Margin="30" />

                <TextBlock x:Name="txtRegisterWaitForSingleObject" Text="click here" MouseLeftButtonDown="txtRegisterWaitForSingleObject_MouseLeftButtonDown" Margin="30" />

        </StackPanel>
</UserControl>
 
ThreadPool.xaml.cs
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 ThreadPool : UserControl
        {
                public ThreadPool()
                {
                        InitializeComponent();
                }

                private void txtMsgQueueUserWorkItem_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
                {
                        // ThreadPool - 线程池的管理类

                        // QueueUserWorkItem(WaitCallback callBack, Object state) - 将指定方法加入线程池队列
                        //         WaitCallback callBack - 需要在新开线程里执行的方法
                        //         Object state - 传递给指定方法的参数
                        System.Threading.ThreadPool.QueueUserWorkItem(DoWork, DateTime.Now);
                }

                private void DoWork(object state)
                {
                        // 作为线程管理策略的一部分,线程池在创建线程前会有一定的延迟
                        // 也就是说线程入队列的时间和线程启动的时间之间有一定的间隔

                        DateTime dtJoin = (DateTime)state;
                        DateTime dtStart = DateTime.Now;
                        System.Threading.Thread.Sleep(3000);
                        DateTime dtEnd = DateTime.Now;

                        // Dispatcher.BeginInvoke() - 在与 Dispatcher 相关联的线程上执行指定的操作。自动线程同步
                        this.Dispatcher.BeginInvoke(() =>
                        {
                                txtMsgQueueUserWorkItem.Text += string.Format("\r\n入队列时间{0} 启动时间{1} 完成时间{2}",
                                        dtJoin.ToString(), dtStart.ToString(), dtEnd.ToString());
                        });
                }


                private void txtRegisterWaitForSingleObject_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
                {
                        System.Threading.AutoResetEvent done = new System.Threading.AutoResetEvent(false);

                        // 为了传递 RegisteredWaitHandle 对象,要将其做一个封装
                        RegisteredWaitHandlePacket packet = new RegisteredWaitHandlePacket();

                        // RegisterWaitForSingleObject - 注册一个 WaitHandle 。在超时或发信号的情况下对指定的回调方法做调用
                        // 第一个参数:需要注册的 WaitHandle
                        // 第二个参数:需要回调的方法(此处省略掉了委托类型)
                        // 第三个参数:传递给回调方法的参数
                        // 第四个参数:超时时间(到超时时间则调用指定的方法)
                        // 第五个参数:是否为一次调用(是到超时时间一次性调用指定的方法,还是每次超时时间后都调用指定的方法)
                        packet.Handle = System.Threading.ThreadPool.RegisterWaitForSingleObject
                                (
                                        done,
                                        WaitOrTimer,
                                        packet,
                                        100,
                                        false
                                );

                        System.Threading.Thread.Sleep(555);
                        done.Set(); // 发出信号,调用 RegisterWaitForSingleObject 所指定的方法
                }

                public void WaitOrTimer(object state, bool timedOut)
                {
                        RegisteredWaitHandlePacket packet = state as RegisteredWaitHandlePacket;

                        // bool timedOut - 是否是因为超时而执行到这里
                        if (!timedOut)    
                        {
                                // 如果不是因为超时而执行到这里(即因为 AutoResetEvent 发出了信号而执行到这里),则注销指定的 RegisteredWaitHandle
                                packet.Handle.Unregister(null);
                        }

                        this.Dispatcher.BeginInvoke(() =>
                        {
                                txtRegisterWaitForSingleObject.Text +=
                                        String.Format("\r\n是否收到信号:{0}", (!timedOut).ToString());
                        });
                }
        }

        /// <summary>
        /// 封装了 RegisteredWaitHandle 的类
        /// </summary>
        public class RegisteredWaitHandlePacket
        {
                public System.Threading.RegisteredWaitHandle Handle { get; set; }
        }
}