上位机学习记录（3）编写用户登录模块

（一）业务逻辑说明

FrmLogin界面的cmb_LoginName控件进行数据绑定，通过SysAdminService.GetAllAdminDB()获取到所有的用户信息

（二）界面初始化逻辑

登陆逻辑：

1. Program.cs： 先调用FrmLogin界面，当FrmLogin完成登陆验证后返回ok,然后启动FrmMain主界面
2. FrmLogin.cs：
   1. 将数据封装为Admin对象
   2. 传入SysAdminService方法
   3. 当SysAdminService查询，查询到返回对象；查询不到返回null
   4. FrmLogin检测Admin对象是否为null，当不为空，返回ok;为null，调用FrmConfirmSingle弹出错误对话框

登陆界面美化：

1. 登陆页面使用无边框。
2. 可以使用鼠标进行拖动

代码展示：

SysAdminService.cs

   public  class SysAdminService
    {
        /// <summary>
        /// 返回所有的用户对象
        /// </summary>
        /// <returns>用户对象集合</returns>
        public static List<SysAdmin> GetAllAdminDB()
        {
            return SqlSugarHelper.SqlSugarClient.Queryable<SysAdmin>().Where(c=>c.LoginName.ToLower()!="admin").ToList();      
        }

        /// <summary>
        /// 验证用户登录结果
        /// </summary>
        /// <param name="admin">用户对象</param>
        /// <returns>用户对象</returns>
        public static SysAdmin AdminLogin(SysAdmin admin)
        {
            var list= SqlSugarHelper.SqlSugarClient.Queryable<SysAdmin>().Where(c => c.LoginName==admin.LoginName&&c.LoginPwd==admin.LoginPwd).ToList();

            return list.Count == 0 ? null : list[0];
        }
     }

SqlSugarService.cs

    public class SqlSugarService
    {
        public static void SetConnectionString(string ConnectionString)
        {
            SqlSugarHelper.ConnectionString = ConnectionString;
        }

    }

SysAdmin.cs

   public class SysAdmin
    {
        public int LoginID { get; set; }

        public string LoginName { get; set; }

        public string LoginPwd { get; set; }

        public int Role { get; set; }

    }

FrmLogin.cs (LoginPwd使用了md5加密)

   public partial class FrmLogin : Form
    {
        public FrmLogin()
        {
            InitializeComponent();
        }

        private void FrmLogin_Load(object sender, EventArgs e)
        {
            this.cmb_LoginName.DataSource = SysAdminService.GetAllAdminDB();

            this.cmb_LoginName.DisplayMember = "LoginName";
        }

        private void btn_Login_Click(object sender, EventArgs e)
        {
            //验证

            if (this.txt_LoginPwd.Text.Trim().Length == 0)
            {
                new FrmConfirmSingle("登录提示", "请输入密码！") { TopMost = true }.ShowDialog();
                this.txt_LoginPwd.Focus();
                return;
            }

            //封装
            SysAdmin objAdmin = new SysAdmin()
            {
                LoginName = this.cmb_LoginName.Text,
                LoginPwd = AuthorizationHelper.Encrypt(this.txt_LoginPwd.Text.Trim())
            };

            objAdmin = SysAdminService.AdminLogin(objAdmin);

            if (objAdmin == null)
            {
                new FrmConfirmSingle("登录提示", "用户名或密码错误！") { TopMost = true }.ShowDialog();
            }
            else
            {
                CommonMethod.sysAdmin = objAdmin;

                this.DialogResult = DialogResult.OK;
            }

        }

        private void MainPanel_DoubleClick(object sender, EventArgs e)
        {
            this.Close();
        }


        Point mPoint;

        private void MainPanel_MouseDown(object sender, MouseEventArgs e)
        {
            mPoint = new Point(e.X, e.Y);
        }

        private void MainPanel_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.Location = new Point(this.Location.X + e.X - mPoint.X, this.Location.Y + e.Y - mPoint.Y);
            }
        }


        private void txt_LoginPwd_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                this.btn_Login_Click(null, null);
            }
        }
    }