winform控件问题

Posted 2023-03-09

登录窗体上面有个用户名文本框,当用户没有输入用户名的时候,提示"用户名不能为空!",
然后怎么让光标聚焦到那个用户名的文本框中? 注释详细点,新手 ,谢谢!解决有追加!!!!

if (textBox1.Text == "")

MessageBox.Show("用户名不能为空");
textBox1.Focus();
return;
参考技术A 全选:select();
焦点:focus(); 参考技术B 不知道你说的是什么语言的开发环境,以下是我用vs2005里的C#语言写的一个简易登录窗体的判断代码.我使用sql数据库,如果你不用你可去掉数据库连接和查询部分.
string tuser;
string tpw;
char[] tchr;
byte[] tb;
string level;
if (TextBox1.Text == "")

MessageBox.Show("用户名不能为空!", "警告", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Warning);
TextBox1.Focus();
return;

tuser = TextBox1.Text;
tpw = TextBox2.Text;
if (tpw.Length > 0)

tchr = tpw.ToCharArray();
tb = new byte[tchr.GetLength(0)];
for (int i = 0; i < tchr.GetLength(0); i++)

tb[i] =(byte)tchr[i];

tpw = Convert.ToBase64String(tb);

if (conn.State != System.Data.ConnectionState.Open)

conn.Open();

cmd = new System.Data.OleDb.OleDbCommand(
"select userlevel from man_user where username='" + tuser + "' and password='" + tpw + "'",conn);
if (cmd.ExecuteScalar() == null)

MessageBox.Show("用户名或密码错误!", "警告", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Warning);
TextBox2.Clear();
TextBox1.Focus();
TextBox1.SelectAll();
this.IsLogin = false;
return;

level = cmd.ExecuteScalar().ToString();
cmd.CommandText = "select tp from man_level where levelname='" + level + "'";
if (cmd.ExecuteScalar() != null)

if (cmd.ExecuteScalar().ToString() == "True")

this.IsLogin = true;
conn.Close();
this.Close();
return;

else

MessageBox.Show("你无权编缉参数!", "警告", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Warning);
TextBox2.Clear();
TextBox1.Focus();
TextBox1.SelectAll();
this.IsLogin = false;
return;


else

MessageBox.Show("你无权编缉参数!", "警告", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Warning);
TextBox2.Clear();
TextBox1.Focus();
TextBox1.SelectAll();
this.IsLogin = false;
return;