c# winform编程之多线程ui界面资源修改总结篇

偏执的太偏执、 2022-01-06 05:39 499阅读 0赞

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(); \});              
        \}   
    \}   
\}

转载于:https://www.cnblogs.com/zhangchenliang/archive/2012/03/15/2397984.html