OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.InitialDirectory = "C:\\Users\\" + System.Environment.UserName + "\\Documents\\";    //初始的文件夹
openFileDialog.Filter = "Image|*.bmp;*.jpeg;*.png|Txt|*.txt|All|*.*";//在对话框中显示的文件类型
openFileDialog.FilterIndex = 3;
openFileDialog.RestoreDirectory = true;
openFileDialog.ShowDialog();    //显示对话框
string filepath = openFileDialog.FileName; //获取选择的文件的全路径名
filePathTb.Text = filepath;