c# winform编程之多线程ui界面资源修改总结篇

单线程的winfom程序中，设置一个控件的值是很easy的事情，直接 this.TextBox1.value = "Hello World!";就搞定了，但是如果在一个新线程中这么做，比如: 

private void btnSet_Click(object sender, EventArgs e) 
{    
    Thread t = new Thread(new ParameterizedThreadStart(SetTextBoxValue)); 
    //当然也可以用匿名委托写成Thread t = new Thread(SetTextBoxValue); 
    t.Start("Hello World"); 
} 

void SetTextBoxValue(object obj) 
{ 
    this.textBox1.Text = obj.ToString(); 
} 

运行时，会报出一个无情的错误： 
线程间操作无效: 从不是创建控件“textBox1”的线程访问它。 

究其原因，winform中的UI控件不是线程安全的，如果可以随意在任何线程中改变其值，你创建一个线程，我创建一个线程，大家都来抢着更改"TextBox1"的值，没有任何秩序的话，天下大乱... 

解决办法: 
1.掩耳盗铃法（Control.CheckForIllegalCrossThreadCalls = false;）--仅Winform有效 
using System; 
using System.Threading; 
using System.Windows.Forms; 

namespace ThreadTest 
{ 
    public partial class Form1 : Form 
    {        

        public Form1() 
        { 
            InitializeComponent(); 
            Control.CheckForIllegalCrossThreadCalls = false;//这一行是关键      
        } 
       

        private void btnSet_Click(object sender, EventArgs e) 
        {           
            Thread t = new Thread(new ParameterizedThreadStart(SetTextBoxValue)); 
            t.Start("Hello World"); 
        } 

        void SetTextBoxValue(object obj) 
        { 
            this.textBox1.Text = obj.ToString(); 
        }        
    } 
} 

设置Control.CheckForIllegalCrossThreadCalls为false,相当于不检测线程之间的冲突，允许各路线程随便乱搞，当然最终TextBox1的值到底是啥难以预料，只有天知道，不过这也是最省力的办法 

2.利用委托调用--最常见的办法（仅WinForm有效） 
using System; 
using System.Threading; 
using System.Windows.Forms; 

namespace ThreadTest 
{ 
    public partial class Form1 : Form 
    { 
        delegate void D(object obj); 

        public Form1() 
        { 
            InitializeComponent();            
        } 
       

        private void btnSet_Click(object sender, EventArgs e) 
        {           
            Thread t = new Thread(new ParameterizedThreadStart(SetTextBoxValue)); 
            t.Start("Hello World"); 
        } 

        void SetTextBoxValue(object obj) 
        { 
            if (textBox1.InvokeRequired) 
            { 
                D d = new D(DelegateSetValue); 
                textBox1.Invoke(d,obj); 

            } 
            else 
            { 
                this.textBox1.Text = obj.ToString(); 
            } 
        } 

        void DelegateSetValue(object obj) 
        { 
            this.textBox1.Text = obj.ToString(); 
        } 
    } 
} 

3.利用SynchronizationContext上下文 -- 最神秘的方法(Winform/Silverlight能用) 

之所以说它神秘，是因为msdn官方对它的解释据说也是不清不楚 
using System; 
using System.Threading; 
using System.Windows.Forms; 

namespace ThreadTest 
{ 
    public partial class Form1 : Form 
    { 
        public Form1() 
        { 
            InitializeComponent();            
        }       

        private void btnSet_Click(object sender, EventArgs e) 
        { 
            Thread t = new Thread(new ParameterizedThreadStart(Run)); 
            MyPram _p = new MyPram() { context = SynchronizationContext.Current, parm = "Hello World" }; 
            t.Start(_p); 
        } 

        void Run(object obj) 
        { 
            MyPram p = obj as MyPram; 
            p.context.Post(SetTextValue, p.parm); 
        } 

        void SetTextValue(object obj) 
        { 
            this.textBox1.Text = obj.ToString(); 
        } 
    } 

    public class MyPram 
    { 
        public SynchronizationContext context { set; get; } 
        public object parm { set; get; } 
    } 
} 

4.利用BackgroundWorker --最偷懒的办法(Winform/Silverlight通用) 

BackgroundWorker会在主线程之外，另开一个后台线程，我们可以把一些处理放在后台线程中处理，完成之后，后台线程会把结果传递给主线程，同时结束自己。 
using System; 
using System.ComponentModel; 
using System.Windows.Forms; 

namespace ThreadTest 
{ 
    public partial class Form1 : Form 
    { 
        public Form1() 
        { 
            InitializeComponent();            
        }       

        private void btnSet_Click(object sender, EventArgs e) 
        { 
            //MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString()); 
            using (BackgroundWorker bw = new BackgroundWorker()) 
            { 
                bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted); 
                bw.DoWork += new DoWorkEventHandler(bw_DoWork); 
                bw.RunWorkerAsync("Hello World"); 
            } 
        } 

        void bw_DoWork(object sender, DoWorkEventArgs e) 
        { 
            //MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString()); 
            e.Result = e.Argument;//这里只是简单的把参数当做结果返回，当然您也可以在这里做复杂的处理后，再返回自己想要的结果(这里的操作是在另一个线程上完成的) 
        } 

        void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) 
        { 
            //这时后台线程已经完成，并返回了主线程，所以可以直接使用UI控件了 
            this.textBox1.Text = e.Result.ToString(); 
            //MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString()); 
        }       
    }    
} 

5.Dispatcher.BeginInvoke--Silverlight的独门秘籍 
代码 
using System.Threading; 
using System.Windows.Controls; 
using System.Windows.Input; 

namespace ThreadTest 
{ 
    public partial class MainPage : UserControl 
    { 
        public MainPage() 
        { 
            InitializeComponent(); 
        } 

        private void LayoutRoot_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) 
        { 
            Thread t = new Thread(SetTextValue); 
            t.Start("Hello World"); 
        } 

        void SetTextValue(object text) 
        { 
            this.Dispatcher.BeginInvoke(() => { this.txt.Text = text.ToString(); });            
        } 
    } 
} 


http://yongkuang.iteye.com/blog/1113426