.net的架构模式

原创

zhangyongshizhi 2022-08-05 22:01:34 博主文章分类：Asp.Net ©著作权

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一：ADO.NET实现三层架构

不用三层的普通的查询写法：

string sql = string.Format("select * from Studnet where StuName like '%{0}%'", txtName.Text);
            string strconn = "server=.;database=MySc;uid=sa;pwd=123456";
            SqlConnection conn = new SqlConnection(strconn);
            SqlDataAdapter da = new SqlDataAdapter("select * fromStuden", conn);
            DataSet ds = new DataSet();
            try
            {
                da.Fill(ds);
               // dataGridView1.DataSource = ds.Tables[0];
                DataTable dt = ds.Tables[0];
                txtName.Text = dt.Rows[0]["Name"].ToString();

            }
            catch (Exception)
            {

                throw;
            }

普通删除的写法：

SqlConnection conn = new SqlConnection("server=.;database=MySc;uid=sa;pwd=123456");
            string id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
            string sql = "delect from Student where stNO=" + id;
            SqlCommand comm = new SqlCommand(sql,conn);
            conn.Open();

修改的普通写法：

string strsql = @"UPDATE Student SET [StuName]='0' WHERE [StuNO]={3}";
            string id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
            string sql = string.Format(strsql, txtName.Text, id);
            SqlConnection conn = new SqlConnection("server=.;database=MySc;uid=sa;pwd=123456");
            SqlCommand com = new SqlCommand(sql, conn);
            try
            {
                conn.Open();
                com.ExecuteNonQuery();
                //刷新数据
            }
            catch (Exception)
            {

                throw;
            }
            finally {
                conn.Close();
            }

一个简单的DbHelper：

private static SqlConnection conn = new SqlConnection("server=.;database=Mys,uid=sa;pwd=123456");

       public static int ExecuteSQL(string strsql)
       {
           SqlCommand comm = new SqlCommand(strsql, conn);
           try
           {
               conn.Open();
               return comm.ExecuteNonQuery();
           }
           catch (Exception ex)
           {

               throw ex;
           }
           finally {
               conn.Close();
           }
       }


       public static int GetDataTable(string strsql)
       {
           SqlDataAdapter da = new SqlDataAdapter(strsql, conn);
           DataSet ds = new DataSet();
           try
           {
               da.Fill(ds);
               return ds.Tables[0];
           }
           catch (Exception ex)
           {
               
               throw ex;
           }
                    
       }

       /// <summary>
       /// 返回一个单一的值
       /// </summary>
       /// <param name="strsql">传入的是select打头的sql语句（select count（*），select max（..））</param>
       /// <returns>返回的是Object类型</returns>
       public static object GetSingle(string strsql)
       {
           SqlCommand comm = new SqlCommand(strsql, conn);
           try
           {
               conn.Open;
               return comm.ExecuteScalar();
           }
           catch (Exception ex)
           {

               throw ex;
           }
           finally {
               conn.Close();
           }
       }

缺点：不是面向对象，客户端不了解后台数据也能完全的操作，而这个三层架构实现不了

解决方案： OOP实现

二：用OOP实现三层架构

private static IList<Student> GetStudentsBySQL(string strsql)
       {
           DataTable dt = DbHelper.GetDataTable(sql);
           IList<Student> result = new List<Student>();
           for (int i = 0; i < dt.Rows.Count; i++)
           {
               Student student = new Student();
               student.Sid = int.Parse(dt.Rows[i]["id"].ToString());
               student.Sname = dt.Rows[i]["Name"].ToString();

               result.Add(student);
           }

           return result;
       }
       /// <summary>
       /// Id查询
       /// </summary>
       /// <param name="id"></param>
       /// <returns></returns>
       public static Student GetStudentById(int id)
       {
           string sql = string.Format("select * from Studnet where stuno={0}", id);
           try
           {
               return GetStudentsBySQL(sql)[0];
           }
           catch (Exception)
           {

               return null;
           }
       }
       
       /// <summary>
       /// 查询所有
       /// </summary>
       /// <returns></returns>
       public static IList<Student> GetAllStudent()
       {
           string sql = "select * from Studnet";
           return GetStudentsBySQL(sql);
        
       }

       /// <summary>
       /// 姓名查询
       /// </summary>
       /// <param name="name"></param>
       /// <returns></returns>
       public static IList<Student> GetStudentByName(string name)
       {
           string strsql = string.Format("select * from student where stuname like '%{0}%'", name);
           return GetStudentByName(strsql);
       }