C#中SaveFileDialog 和OpenFileDialog 的用法

1.OpenFileDialog

        private void btnOpen_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.InitialDirectory = @"C:\Users\LWP1398\Desktop"; //設置初始路徑
            ofd.Filter = "Excel文件(*.xls)|*.xls|Csv文件(*.csv)|*.csv|所有文件(*.*)|*.*"; //設置“另存為文件類型”或“文件類型”框中出現的選擇內容
            ofd.FilterIndex = 2; //設置默認顯示文件類型為Csv文件(*.csv)|*.csv
            ofd.Title = "打開文件"; //獲取或設置文件對話框標題
            ofd.RestoreDirectory = true;
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                //FileName：所選文件的全路徑  SafeFileName：所選的文件名
                txtPath.Text = "FileName:" + ofd.FileName + "\r\n" + "SafeFileName:" + ofd.SafeFileName;
            }
        }

2.OpenFileDialog選擇多個文件

        private void button3_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.InitialDirectory = @"C:\Users\LWP1398\Desktop"; //設置初始路徑
            ofd.Filter = "Excel文件(*.xls)|*.xls|Csv文件(*.csv)|*.csv|所有文件(*.*)|*.*"; //設置“另存為文件類型”或“文件類型”框中出現的選擇內容
            ofd.FilterIndex = 2; //設置默認顯示文件類型為Csv文件(*.csv)|*.csv
            ofd.Title = "打開文件"; //獲取或設置文件對話框標題
            ofd.RestoreDirectory = true;////設置對話框是否記憶上次打開的目錄

            ofd.Multiselect = true;//設置多選
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                for (int i = 0; i < ofd.FileNames.Length; i++)
                {
                    txtPath.Text += ofd.FileNames[i] + "\r\n";//輸出一個路徑回車換行
                }
                for (int i = 0; i < ofd.FileNames.Length; i++)
                {
                    txtPath.Text += ofd.SafeFileNames[i] + "\r\n";
                }
            }
        }

3.SaveFileDialog

        private void button2_Click(object sender, EventArgs e)
        {
            SaveFileDialog sfd=new SaveFileDialog();
            sfd.Filter = "文本文件(*.txt)|*.txt|所有文件|*.*";//設置文件類型
            sfd.FileName = "保存";//設置默認文件名
            sfd.DefaultExt = "txt";//設置默認格式（可以不設）
            sfd.AddExtension = true;//設置自動在文件名中添加擴展名
            if (sfd.ShowDialog()==DialogResult.OK)
            {
                txtPath.Text = "FileName:" + sfd.FileName + "\r\n" ;
                using (StreamWriter sw = new StreamWriter(sfd.FileName))
                {              
                    sw.WriteLineAsync("今天是個好天氣");
                }
            }
            MessageBox.Show("ok");
        }