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最新推荐文章于 2019-01-16 12:03:39 发布

原创最新推荐文章于 2019-01-16 12:03:39 发布 · 1.6k 阅读

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CC 4.0 BY-SA版权

本文介绍了一个使用C#编写的简单Windows窗体应用程序，该程序实现了基本的用户登录功能，并通过连接本地数据库来验证用户名和密码的有效性。

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class CAPTION : Form
    {
        public string ww = string.Empty;
        public CAPTION()
        {
            InitializeComponent();
        }

        private void CAPTION_Load(object sender, EventArgs e)
        {
            
            this.textBox1.Text = ww;
            
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data;



namespace WindowsFormsApplication2
{
    class Tool
    {
        public string MM = "Data Source=.;User ID=bdqn;Password=123";

        private SqlConnection connection;

        public SqlConnection Connection {
            get { 
            if(connection==null)
            {
                connection = new SqlConnection(MM);
            }
            return connection;
            
            }
        }
        public void OpenConnection() { 
        if(Connection.State==ConnectionState.Closed){
            Connection.Open();    
        }
        else if( Connection.State==ConnectionState.Broken)
        {
            Connection.Close();
            Connection.Open();
        }
        }

        public void CloseConnection()
        {
            if(Connection.State==ConnectionState.Open||Connection.State==ConnectionState.Broken)
            {
                Connection.Close();

            }


        }



    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;




namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void label2_Click(object sender, EventArgs e)
        {
            DialogResult result = MessageBox.Show("确认取消登陆吗?", "操作提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            if (result == DialogResult.Yes)
            {
                this.Close();
            }
        }

        //登录按钮事件
       

      

        public bool checkInput()
        {
            if (this.textBox1.Text.Trim().Equals(string.Empty))
            {

                MessageBox.Show("请输入您名字:", "请输入提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                this.name.Focus();
                return false;
            }
            else if (this.textBox2.Text.Trim().Equals(string.Empty))
            {
                MessageBox.Show("请输入您密码:", "请输入提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                this.name.Focus();
                return false;

            }
            else if (this.comboBox1.Text.Trim().Equals(string.Empty))
            {

                MessageBox.Show("请输入登录类型:", "请输入提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                this.name.Focus();
                return false;

            }
            else
            {

                return true;
            }
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        public bool CheckUser(ref string message)
        {
            bool isValidUser = false;
            string userName = textBox1.Text.Trim();
            string userpwd = textBox2.Text.Trim();
            StringBuilder sb = new StringBuilder();
            if (comboBox1.Equals("管理员"))
            {
                sb.AppendFormat("select count(1) from Table_1" + "where name='{0}'and pwd='{1}'", userName, userpwd);
            }
            int count = 0;
            Tool db = new Tool();
            try
            {
                SqlCommand com = new SqlCommand(sb.ToString(), db.Connection);
                db.OpenConnection();
                count = (int)com.ExecuteScalar();
                if (count > 0)
                {
                    isValidUser = true;
                }
                else
                {
                    MessageBox.Show("用户和密码不存在");
                    isValidUser = false;

                }
            }
            catch (Exception)
            {
                message = "系统发生错误,请稍后再试!";
                isValidUser = false;
            }
            finally
            {
                db.CloseConnection();
            }
            return isValidUser;
        }


        private void button1_Click_1(object sender, EventArgs e)
        {
            //if (checkInput())
            //{
            //    string message = string.Empty;
            //    if (CheckUser(ref message))
            //    {

            //        if (this.comboBox1.Text.Equals("管理员"))
            //        {

            //            CAPTION s = new CAPTION();
            //            s.Show();
            //        }
            //        this.Hide();
            //    }


                       CAPTION s = new CAPTION();
                      
                       s.Show();






             }
           

         

        }
    }