private void openFileDialogBTN_Click(object sender, System.EventArgs e)
{
    OpenFileDialog openFileDialog = new OpenFileDialog();
    openFileDialog.InitialDirectory = "c:\";//注意这里写路径时要用c:\而不是c:
    openFileDialog.Filter = "文本文件|*.*|C#文件|*.cs|所有文件|*.*";
    openFileDialog.RestoreDirectory = true;
    openFileDialog.FilterIndex = 1;
    if (openFileDialog.ShowDialog() == DialogResult.OK)
    {
    fName = openFileDialog.FileName;
    File fileOpen = new File(fName);
    isFileHaveName = true;
    richTextBox1.Text = fileOpen.ReadFile();
    richTextBox1.AppendText("");
    }
}

#region saveFileDialog的实现
            {
                //string localFilePath, fileNameExt, newFileName, FilePath;  
                string localFilePath = String.Empty;
                SaveFileDialog saveFileDialog1 = new SaveFileDialog();

                //设置文件类型  
                saveFileDialog1.Filter = " xls files(*.xls)|*.txt|All files(*.*)|*.*";
                //设置文件名称：
                saveFileDialog1.FileName = DateTime.Now.ToString("yyyyMMdd") + "-" + "资产信息报表.xls";

                //设置默认文件类型显示顺序  
                saveFileDialog1.FilterIndex = 2;

                //保存对话框是否记忆上次打开的目录  
                saveFileDialog1.RestoreDirectory = true;

                //点了保存按钮进入  
                if (saveFileDialog1.ShowDialog() == DialogResult.OK)
                {
                    //获得文件路径  
                    localFilePath = saveFileDialog1.FileName.ToString();
                    //string filname = this.openFileDialog2.FileName;
                    //获取文件名，不带路径  
                    //fileNameExt = localFilePath.Substring(localFilePath.LastIndexOf("\\") + 1);  

                    //获取文件路径，不带文件名  
                    //FilePath = localFilePath.Substring(0, localFilePath.LastIndexOf("\\"));  

                    //给文件名前加上时间  
                    //newFileName = DateTime.Now.ToString("yyyyMMdd") + fileNameExt;  

                    //在文件名里加字符  
                    //saveFileDialog1.FileName.Insert(1,"dameng");  

                    //System.IO.FileStream fs = (System.IO.FileStream)saveFileDialog1.OpenFile();//输出文件  

                    //fs输出带文字或图片的文件，就看需求了  
                }
               
            }

            if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
            {
                string filename = folderBrowserDialog1.SelectedPath;
                txtboxstring.Text = filename;
            }