private void button1_Click(object sender, EventArgs e)
 {
     if (this.mode_edit)
     {
         if (BookAPI.EditBook(Program.books, txtBookID.Text, txtBookName.Text, txtBookAuthor.Text, txtBookCount.Text))
         {
             MessageBox.Show("修改成功");
             Close();
             return;
         }
         MessageBox.Show("修改失败");
     }
     else
     {
         if (BookAPI.AddBook(Program.books, txtBookName.Text, txtBookAuthor.Text, txtBookCount.Text))
         {
             MessageBox.Show("添加成功");
             Close();
             return;
         }
         MessageBox.Show("添加失败");
         return;
     }
 }