手写ORM框架
先准备Models中实体类
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/// 用户信息
/// </summary>
[Serializable]
public class Student_Info
{
[Identity]
[PrimaryKey]
public int ID { get; set; }
public string Name { get; set; }
public bool Sex { get; set; }
public string ClassName { get; set; }
public string BookName { get; set; }
public DateTime BeginDateTime { get; set; }
public DateTime EndDateTime { get; set; }
[Peculiarity]
public int ClassID { get; set; }
}
然后建立属性过滤的类：AttributeClass
必须要用Attribute结尾，继承Attribute类
/// <summary>
/// 标识列属性
/// </summary>
public class IdentityAttribute:Attribute
{
public bool IsIdentity { get; } = true;
}
/// <summary>
/// 主键属性
/// </summary>
public class PrimaryKeyAttribute : Attribute
{
public bool IsPrimaryKey { get; } = true;
}
/// <summary>
/// 特性属性
/// </summary>
public class PeculiarityAttribute : Attribute
{
public bool IsPrimaryKey { get; } = true;
}
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准备DAL中的工作：
建立一个文件夹：ORM.Core；
建立一个DBContext的类；
namespace DAL
{
/// <summary>
/// ORM框架的核心操作（数据库上下文）
/// </summary>
public class DBContext
{
/// <summary>
/// 添加
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="model"></param>
/// <returns></returns>
public int InsertModel<T>(T model) where T:class,new()
{
//1.获取当前实体类的所有属性（属性名称、类型、具体的属性值）
PropertyInfo[] properites = model.GetType().GetProperties();
//2.过滤掉不需要的属性
List<string> columns = FilterColumnsByAttributes(properites, new string[] { "IdentityAttribute", "PeculiarityAttribute" });
//3.准备
StringBuilder sqlFields = new StringBuilder($"insert into {model.GetType().Name}(");
StringBuilder sqlValues = new StringBuilder(" values(");
List<SqlParameter> paramList = new List<SqlParameter>();
//4.循环生成sql语句和参数封装
foreach (PropertyInfo item in properites)
{
//过滤不需要的字段
if (columns.Contains(item.Name)) continue;
//过滤属性值为null的
if (item.GetValue(model) == null) continue;
//时间属性过滤
sqlFields.Append($"{item.Name},");
sqlValues.Append($"@{item.Name},"); //values值是参数，必须加@符号进行参数化防注入
paramList.Add(new SqlParameter($"@{item.Name}", item.GetValue(model)));
}
string sql1 = sqlFields.ToString().TrimEnd(',') + ")";
string sql2 = sqlValues.ToString().TrimEnd(',') + ")";
string sql = sql1 + sql2;
//5.调用SQLHelper通用类完成数据库操作
return SQLHelper.ExecuteNonQuery(sql, paramList.ToArray());
}
/// <summary>
/// 过滤不需要的属性
/// </summary>
/// <param name="properites"></param>
/// <param name="attrNames"></param>
/// <returns></returns>
private List<string> FilterColumnsByAttributes(PropertyInfo[] properites,string[] attrNames)
{
List<string> columns = new List<string>();
foreach (string attrName in attrNames)
{
foreach (PropertyInfo item in properites)
{
object[] cusAttrbutes = item.GetCustomAttributes(true);//找到当前属性的所有自定义特性
foreach (var attribute in cusAttrbutes)
{
if(attribute.GetType().Name.Equals(attrName))
{
columns.Add(item.Name);
break;
}
}
}
}
return columns;
}
}
}
附上SQLHelper类；
public class SQLHelper
{
//定义一个私有的、只读的、静态的变量（获取config文件中的数据库连接）
private readonly static string str = ConfigurationManager.ConnectionStrings["myweb"].ConnectionString;
/// <summary>
/// 执行方法ExecuteScalar，返回查询到的首行首列
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static object ExecuteScalar(string sql, params SqlParameter[] pams)
{
using (SqlConnection con = new SqlConnection(str))
{
using (SqlCommand com = new SqlCommand(sql, con))
{
if (pams != null && pams.Length > 0)
{
com.Parameters.AddRange(pams);
}
if (con.State == ConnectionState.Closed)
{
con.Open();
}
return com.ExecuteScalar();
}
}
}
/// <summary>
/// 执行方法ExecuteNonQuery，返回受影响的行数
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static int ExecuteNonQuery(string sql, params SqlParameter[] pams)
{
using (SqlConnection con = new SqlConnection(str))
{
using (SqlCommand com = new SqlCommand(sql, con))
{
if (pams != null && pams.Length > 0)
{
com.Parameters.AddRange(pams);
}
if (con.State == ConnectionState.Closed)
{
con.Open();
}
return com.ExecuteNonQuery();
}
}
}
/// <summary>
/// 执行方法ExecuteReader，返回SqlDataReader读取的数据
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static SqlDataReader ExecuteReader(string sql, params SqlParameter[] pams)
{
SqlConnection con = new SqlConnection(str);
using (SqlCommand com = new SqlCommand(sql, con))
{
if (pams != null && pams.Length > 0)
{
com.Parameters.AddRange(pams);
}
if (con.State == ConnectionState.Closed)
{
con.Open();
}
return com.ExecuteReader();
}
}
/// <summary>
/// 执行ExecuteDataTable方法，返回DataTable
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static DataTable ExecuteDataTable(string sql, params SqlParameter[] pams)
{
using (SqlDataAdapter sda = new SqlDataAdapter(sql, str))
{
if (pams != null)
{
sda.SelectCommand.Parameters.AddRange(pams);
}
DataTable dt = new DataTable();
sda.Fill(dt);
return dt;
}
}
/// <summary>
/// 用存储过程执行方法ExecuteReaderProc，返回SqlDataReader读取的数据
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static SqlDataReader ExecuteReaderProc(string sql, params SqlParameter[] pams)
{
SqlConnection con = new SqlConnection(str);
using (SqlCommand com = new SqlCommand(sql, con))
{
com.CommandType = CommandType.StoredProcedure;
if (pams != null && pams.Length > 0)
{
com.Parameters.AddRange(pams);
}
if (con.State == ConnectionState.Closed)
{
con.Open();
}
return com.ExecuteReader();
}
}
/// <summary>
/// 使用存储过程执行方法ExecuteNonQueryPrco，返回受影响的行数
/// </summary>
/// <param name="sql"></param>
/// <param name="pams"></param>
/// <returns></returns>
public static int ExecuteNonQueryPrco(string sql, params SqlParameter[] pams)
{
using (SqlConnection con = new SqlConnection(str))
{
using (SqlCommand com = new SqlCommand(sql, con))
{
com.CommandType = CommandType.StoredProcedure;
if (pams != null && pams.Length > 0)
{
com.Parameters.AddRange(pams);
}
if (con.State == ConnectionState.Closed)
{
con.Open();
}
return com.ExecuteNonQuery();
}
}
}
}
===================================================
DAL中的Service类；
namespace DAL
{
//定义一个泛型，条件：必须是引用类型，无参
public class Service<T> where T:class,new()
{
/// <summary>
/// 添加实体方法
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public int Add(T entity)
{
DBContext db = new DBContext();
return db.InsertModel(entity);
}
}
}
===================================================
BLL中写为泛型；
public class Manager<T> where T : class, new()
{
Service<T> a = new Service<T>();
/// <summary>
/// BLL中的添加数据
/// </summary>
/// <param name="student"></param>
/// <returns></returns>
public int Insert(T entity)
{
return a.Add(entity);
}
}
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前台代码调用；
Manager<Student_Info> BLL_MG = new Manager<Student_Info>();
Student_Info info = new Student_Info();
info.ID = 14;
info.Name = "王五";
info.Sex = true;
info.ClassName = "王五";
info.BookName = "C#从入门到精通";
info.BeginDateTime = DateTime.Parse(DateTime.Parse("2019-01-01").ToString("yyyy-MM-dd HH:mm:ss"));
info.EndDateTime = DateTime.Parse(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
BLL_MG.Insert(info);
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