C#使用多线程，推荐使用BackgroundWorker。
1、定义：
BackgroundWorker BgWorker = new BackgroundWorker();
2、初始化：
BgWorker.WorkerReportsProgress = true;
BgWorker.DoWork += BgWorker_DoWork;
BgWorker.ProgressChanged += BgWorker_ProgressChanged;
BgWorker.RunWorkerCompleted += BgWorker_RunWorkerCompleted;
其中DoWork是线程要执行的函数。
ProgressChanged 是进度更新时的回调函数
RunWorkerCompleted 是线程执行完成时的回调函数，这个函数里面可以直接调用UI线程的东西。
注意：不可以把BackgroundWorker的DoWork等接口进行多次赋值，否则会造成目标函数被多次调用的问题。正确的做法是，每次需要重新赋值的时候，都进行BgWorker = new BackgroundWorker()操作。
3、函数体实现：
void BgWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
int progress = e.ProgressPercentage;
LabelProgress.Text = string.Format("完成{0}%", progress);
LabelProgress.Left = (this.Width - LabelProgress.Width) / 2;
}
void BgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (PictureList.Count > 0)
{
ShowPicture(curIndex);
}
LabelProgress.Visible = false;
}
void BgWorker_DoWork(object sender, DoWorkEventArgs e)
{
List<string> picList = new List<string>();
string[] extList = { ".jpg", ".png" };
int index = 0;
foreach (string item in fileList)
{
if (extList.Contains(System.IO.Path.GetExtension(item).ToLower()) == true)
{
string backName = AddImageToDB(item);
Debug.WriteLine("ImageName:" + backName);
if (string.IsNullOrEmpty(backName) == false)
picList.Add(backName);
}
index++;
BgWorker.ReportProgress(100 * index / fileList.Count);
}
curIndex = PictureList.Count;
PictureList.AddRange(picList);
}
