C# 进度条封装

主要是使用BackgroundWorker控件实现异步刷新……

public class ProgressTool
{
    private BackgroundWorker backgroundWorkerProgress;

    public ProgressTool()
    {
        // 
        // backgroundWorkerProgress
        // 
        this.backgroundWorkerProgress = new System.ComponentModel.BackgroundWorker();
        this.backgroundWorkerProgress.WorkerReportsProgress = true;
        this.backgroundWorkerProgress.WorkerSupportsCancellation = true;
        this.backgroundWorkerProgress.DoWork += new System.ComponentModel.DoWorkEventHandler(this.backgroundWorkerProgress_DoWork);
        this.backgroundWorkerProgress.RunWorkerCompleted += new System.ComponentModel.RunWorkerCompletedEventHandler(this.backgroundWorkerProgress_RunWorkerCompleted);
    }

    public void StartBar(Form dialog, int maxVal)
    {
        // 为了开始在后台操作，必须调用BackgroundWorker的RunWorkerAsync()方法，当调用此方时，BackgroundWorker 通过触发DoWork 事件，开始执行后台操作，DoWork 事件的代码是在另一个线程里执行的。
        if (this.backgroundWorkerProgress.IsBusy)
            return;
        this.backgroundWorkerProgress.RunWorkerAsync(maxVal);

        // 显示进度条窗体 
        FormProgress form = new FormProgress(this.backgroundWorkerProgress);
        form.ShowDialog(dialog);
        form.Close();
    }

    public Func<int, string> BackgroundFunc = null;
    private void backgroundWorkerProgress_DoWork(object sender, DoWorkEventArgs e)
    {
        int maxval = Convert.ToInt32(e.Argument);

        BackgroundWorker worker = sender as BackgroundWorker;
        for (int i = 0; i < maxval; i++)
        {
            if (this.BackgroundFunc != null)
            {
                string strShow = BackgroundFunc(i);

                // 注意：这里向子窗体返回信息值，这里是两个值，一个用于进度条，一个用于文本框的。
                worker.ReportProgress((int)(i * 100.0f / maxval), strShow + "\r\n");
            }

            // 如果用户取消则跳出处理数据代码 
            if (worker.CancellationPending)
            {
                // 利用CancellationPending 属性，可以判断是否取消后台异步操作。
                e.Cancel = true;
                break;
            }
        }
        // 在执行DoWork 事件时，DoWorkEventArgs 实例的Result 属性，返回值到用户；在RunWorkerCompleted 事件里，RunWorkerCompletedEventArgs 实例的Result 属性接收值；
    }

    private void backgroundWorkerProgress_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        // 当后台操作完成以后，无论是completed 还是cancelled，RunWorkerCompleted 事件被触发，通过此方法可以将后台操作的完成结果反馈给用户；
        // 另外，通过RunWorkerCompletedEventArgs实例的Cancelled 属性，以判断是否是Cancel操作使得后台操作终止；
        if (e.Error != null)
        {
            MessageBox.Show("发生异常错误 -> " + e.Error.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        else if (e.Cancelled)
        {
            MessageBox.Show("用户取消", "已取消", MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
        else
        {
            // 执行完成
        }
    }
}

public partial class FormProgress : Form
{
    //ProcessForm 窗体事件(进度条窗体)
    private BackgroundWorker backgroundWorkerBar = null; 
    public FormProgress(BackgroundWorker backWorker)
    {
        InitializeComponent();

        this.backgroundWorkerBar = backWorker;
        this.backgroundWorkerBar.ProgressChanged += new ProgressChangedEventHandler(backgroundWorkerBar_ProgressChanged);
        this.backgroundWorkerBar.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorkerBar_RunWorkerCompleted);
    }

    private void backgroundWorkerBar_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        // 为了显示后台操作的执行进度，首先要使WorkerReportsProgress 等于true，然后调用BackgroundWorker的ReportProgress()方法，通过它传递操作完成的进度值
        // 此外，该方法触发ProgressChanged事件，在是此事件中，通过ProgressChangedEventArgs的实例，接收到主线程传递过来的参数。
        this.progressBarShow.Value = e.ProgressPercentage;
        //主窗体传过来的值，通过e.UserState.ToString()来接受
        this.textBoxBar.AppendText(e.UserState.ToString());
    }

    private void backgroundWorkerBar_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        //执行完之后，直接关闭页面
        this.Close();
    }

    private void buttonCancel_Click(object sender, EventArgs e)
    {
        // 为了使 BackgroundWorker 可以取消后台正在执行的操作，首先要把属性WorkerSupportsCancellation 的值设置为 true。
        // 接着调用CancelAsync()方法，该方法使得属性CancellationPending 为true，
        this.backgroundWorkerBar.CancelAsync();
        this.buttonCancel.Enabled = false;
        this.Close();
    }
}