private void button7_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog fbd = new FolderBrowserDialog();
            fbd.SelectedPath = "D:";//默认打开d盘
            if (fbd.ShowDialog() == DialogResult.OK)
            {
                textBox1.Text = fbd.SelectedPath;

                DirectoryInfo dif = new DirectoryInfo(textBox1.Text);
                FileInfo[] fis = dif.GetFiles();//取所有文件信息

                foreach (FileInfo fi in fis)
                {
                    if (fi.Name.ToLower().Contains(".xls") ||
                       fi.Name.ToLower().Contains(".xlsx"))
                    {

                        listView1.Items.Add(fi.Name);
                    }

                }

            }
        }

 OpenFileDialog fd = new OpenFileDialog();
            fd.Multiselect = true;
            fd.Filter = "所有的excel文件|*.xls;*.xlsx";
           
            if (fd.ShowDialog() == DialogResult.OK)
            {
                

                //只显示名称+扩展名
                foreach (string s in fd.SafeFileNames)
                {
                    listView1.Items.Add(s);
                }

                //显示全路径
                foreach (string s in fd.FileNames)
                {
                    listView1.Items.Add(s);

                }
            };