winform中,工作线程是无法访问主线程得控件,还是不推荐直接访问

Question

是不推荐的,至于如何用BeginInvoke等方法,我可以给出一个例子看看:
namespace Microsoft.Samples.WinForms.Cs.ThreadMarshal {
    using System;
    using System.ComponentModel;
    using System.Drawing;
    using System.Windows.Forms;
    using System.Threading;
    public class ThreadMarshal : System.Windows.Forms.Form {
        private System.ComponentModel.IContainer components;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.Button button2;
        private System.Windows.Forms.ProgressBar progressBar1;        private Thread timerThread;        public ThreadMarshal() {            // Windows 窗体设计器所必需的
            InitializeComponent();        }        //在背景线程上执行此函数 - 它封送处理调用以
        //将用户界面更新回前景线程
        public void ThreadProc() {            try {
                MethodInvoker mi = new MethodInvoker(this.UpdateProgress);
                while (true) {
                    //在窗体上调用 BeginInvoke
                    this.BeginInvoke(mi);
                    Thread.Sleep(500) ;
                }
            }
            //当该线程被主线程中断时引发 - 退出该循环
            catch (ThreadInterruptedException) {
                //只需退出....
            }
            catch (Exception) {
            }
        }        //此函数是从背景线程调用的
        private void UpdateProgress() {            //如果需要，重置启动
            if (progressBar1.Value == progressBar1.Maximum) {
                progressBar1.Value = progressBar1.Minimum ;
            }            progressBar1.PerformStep() ;
        }        //启动背景线程以更新进度栏
        private void button1_Click(object sender, System.EventArgs e) {
            StopThread();
            timerThread = new Thread(new ThreadStart(ThreadProc));
            timerThread.IsBackground = true;
            timerThread.Start();
        }        //停止背景线程以更新进度栏
        private void button2_Click(object sender, System.EventArgs e) {
            StopThread();
        }        //停止背景线程
        private void StopThread()
        {
            if (timerThread != null)
            {
                timerThread.Interrupt();
                timerThread = null;
            }
        }        protected override void Dispose(bool disposing)
        {
           StopThread();
           if (disposing) {
                if (components != null) {
                    components.Dispose();
                }
           }           base.Dispose(disposing);
        }        private void InitializeComponent()
        {
            this.button1 = new System.Windows.Forms.Button();
            this.button2 = new System.Windows.Forms.Button();
            this.progressBar1 = new System.Windows.Forms.ProgressBar();
            this.SuspendLayout();
            // 
            // button1
            // 
            this.button1.Font = new System.Drawing.Font("宋体", 9F, System.Drawing.FontStyle.Bold);
            this.button1.Location = new System.Drawing.Point(164, 74);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(153, 46);
            this.button1.TabIndex = 1;
            this.button1.Text = "开始！";
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // button2
            // 
            this.button2.Font = new System.Drawing.Font("宋体", 9F, System.Drawing.FontStyle.Bold);
            this.button2.Location = new System.Drawing.Point(328, 74);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(153, 46);
            this.button2.TabIndex = 1;
            this.button2.Text = "停止！";
            this.button2.Click += new System.EventHandler(this.button2_Click);
            // 
            // progressBar1
            // 
            this.progressBar1.Font = new System.Drawing.Font("宋体", 8F, System.Drawing.FontStyle.Bold);
            this.progressBar1.Location = new System.Drawing.Point(13, 12);
            this.progressBar1.Name = "progressBar1";
            this.progressBar1.Size = new System.Drawing.Size(448, 46);
            this.progressBar1.TabIndex = 2;
            this.progressBar1.Text = "开始！";
            // 
            // ThreadMarshal
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(501, 135);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.button1,
                                                                          this.button2,
                                                                          this.progressBar1});
            this.Name = "ThreadMarshal";
            this.Text = "已使用设计器生成";
            this.ResumeLayout(false);        }        [STAThread]
        public static void Main(string[] args) {
            Application.Run(new ThreadMarshal());
        }
    }
}

Answer 1

还有我不明白join方法得作用,能不能说说

Answer 2

Join()是保证线程结束，线程不结束就强行结束。

Answer 3

解释一下:
在线程调用About方法后,线程并不是立刻终止,要等线程的所有finally快中的代码完成后才会完全终止. 所以在主线程中可以用Join方法来同步,当线程还未完全终止时,t.Join()将处于等待,直到t线程完全结束后再继续执行后面的语句.

Answer 4

那么join方法还有什么其他作用