OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Multiselect = true;
            openFileDialog.Filter = "图片文件(*.jpg,*.jpeg,*.gif,*.bmp,*.png)|*.jpg;*.jpeg;*.gif;*.bmp;*.png";
            if (openFileDialog.ShowDialog()== DialogResult.OK)
            {
                foreach (string s in openFileDialog.FileNames)
                {
                    MessageBox.Show(s);
                }
            }