标签：adapter ext 入门 val list except value space reading
本人大二菜鸟一只,今天在上课期间有个同学看着C#反射的内容说反射没什么用,一时之间也想不到什么更好的例子,就写了个根据泛型类型和游标反射创建List集合的Demo.
首先创建一个用于封装对应数据的entity,代码如下.
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Test { public class EUserInfo { public int UserId { get; set; } public string UserCode { get; set; } public string UserName { get; set; } public string UserPwd { get; set; } public string Gender { get; set; } public override string ToString() { return "UserId:"+UserId+"|UserCode:"+UserCode+"|UserName:"+UserName+"|UserPwd:"+UserPwd+"|Gender:"+Gender; } } }
这里我重写了ToString方法,以便待会儿更直观的看到效果.
接下来创建EUserInfo实体类对应的table,sql如下:
use master go if exists (select * from sys.databases where name=‘reflectDemoDB‘) drop database reflectDemoDB create database reflectDemoDB go use reflectDemoDB go create table UserInfo( UserId int primary key identity, UserCode varchar(20) not null, UserName varchar(20) not null, UserPwd varchar(20) not null, Gender char(2) check(Gender in (‘男‘,‘女‘)) ) go insert into UserInfo values(‘111111111‘,‘我体会过你的不完美。‘,‘123‘,‘男‘) insert into UserInfo values(‘222222222‘,‘寂寞陪伴着‘,‘123‘,‘男‘) insert into UserInfo values(‘333333333‘,‘偏执的眼眸︼╯‘,‘123‘,‘男‘)
为了可以方便操作ado对象我这里写了一个工具类DBHelper,代码如下:
using System; using System.Collections.Generic; using System.Web; using System.Data.SqlClient; using System.Data; using System.Configuration; namespace Test { /// <summary> ///DBHelper：数据库访问操作类 /// </summary> public class DBHelper { /// <summary> /// 更新操作：增，删，改 共用 /// </summary> /// <param name="sql"></param> /// <returns>bool</returns> public static bool UpdateOpera(string sql,params SqlParameter[] sps) { SqlCommand cmd = new SqlCommand(sql, Connection); //////////////////将配置参数加入到Command中 cmd.Parameters.AddRange(sps); ///////////////// return cmd.ExecuteNonQuery() > 0; } /// <summary> /// 单个查询操作：返回首行首列数据 /// </summary> /// <param name="sql">查询SQL语句</param> /// <returns>object</returns> public static object GetScalar(string sql, params SqlParameter[] sps) { SqlCommand cmd = new SqlCommand(sql, Connection); //////////////////将配置参数加入到Command中 cmd.Parameters.AddRange(sps); ///////////////// return cmd.ExecuteScalar(); } /// <summary> /// 多行查询操作：返回SqlDataReader /// </summary> /// <param name="sql">查询SQL语句</param> /// <returns>SqlDataReader</returns> public static SqlDataReader GetReader(string sql, params SqlParameter[] sps) { SqlCommand cmd = new SqlCommand(sql, Connection); //////////////////将配置参数加入到Command中 cmd.Parameters.AddRange(sps); ///////////////// return cmd.ExecuteReader(); } /// <summary> /// 多行查询操作：返回DataTable /// </summary> /// <param name="sql">查询SQL语句</param> /// <returns>DataTable</returns> public static DataTable GetDataTable(string sql, params SqlParameter[] sps) { DataTable dt = new DataTable(); SqlDataAdapter dad = new SqlDataAdapter(sql, Connection); //////////////////将配置参数加入到Command中 dad.SelectCommand.Parameters.AddRange(sps); ///////////////// dad.Fill(dt); return dt; } public static List<string> GetColumnsByTableName(string tableName) { List<string> columnList = new List<string>(); string sql = "select name from syscolumns where id=object_id(@tableName)"; SqlDataReader sdr = GetReader(sql, new SqlParameter("@tableName", tableName)); while (sdr.Read()) { columnList.Add(sdr["name"].ToString()); } sdr.Close(); return columnList; } private static SqlConnection _connection; /// <summary> /// Connection对象 /// </summary> public static SqlConnection Connection { get { string connectionString = "Data Source=.;Initial Catalog=reflectDemoDB;Integrated Security=True"; if (_connection == null) { _connection = new SqlConnection(connectionString); _connection.Open(); } else if (_connection.State == ConnectionState.Closed) { _connection.Open(); } else if (_connection.State == ConnectionState.Broken || _connection.State == ConnectionState.Open) { _connection.Close(); _connection.Open(); } return _connection; } } } }
接下来就可以进入主题了,我这里是用一个BaseDao做例子,代码如下:
using System; using System.Collections.Generic; using System.Data.SqlClient; using System.Linq; using System.Reflection; using System.Text; using System.Threading.Tasks; namespace Test { public class BaseDao<T> { /// <summary> /// 获取泛型对应的实体类类名当做表名 /// </summary> private static string TableName { get { return typeof(T).Name.Replace("E",""); } } /// <summary> /// 获取泛型对应实体类所有属性 /// </summary> private static PropertyInfo[] Properties { get { return typeof(T).GetProperties(); } } /// <summary> /// 通用查询所有方法 /// </summary> /// <returns></returns> public List<T> GetAll() { //根据获取的表名拼装出sql语句 string sql = "select * from " + TableName; SqlDataReader sdr = DBHelper.GetReader(sql); return CreateInstanceListOfSqlDataReader<T>(sdr); } private static T CreateInstance<T>(SqlDataReader sdr) { //或许泛型类所有属性 //根据泛型T创建它的实例 T t = (T)Activator.CreateInstance(typeof(T)); //遍历该类所有属性 foreach (PropertyInfo pro in Properties) { //判断属性类型 如果是对应类型就强转进行赋值 if (pro.PropertyType.Equals(typeof(DateTime))) try { pro.SetValue(t, Convert.ToDateTime(sdr[pro.Name]));//利用游标根据属性名获取对应列值给属性赋值 } catch (Exception) { throw new Exception("转换DateTime类型失败,[" + pro.Name + "]字段[value=" + sdr[pro.Name].ToString() + "]格式不正确"); } else if (pro.PropertyType.Equals(typeof(int))) try { pro.SetValue(t, Convert.ToInt32(sdr[pro.Name])); } catch (Exception) { throw new Exception("转换int类型失败,[" + pro.Name + "]字段[value=" + sdr[pro.Name].ToString() + "]格式不正确"); } else if (pro.PropertyType.Equals(typeof(double))) try { pro.SetValue(t, Convert.ToDouble(sdr[pro.Name])); } catch (Exception) { throw new Exception("转换Double类型失败,[" + pro.Name + "]字段[value=" + sdr[pro.Name].ToString() + "]格式不正确"); } else pro.SetValue(t, sdr[pro.Name]); } return t; } /// <summary> /// 根据游标sdr创建一个所传类型对象集合并返回 /// </summary> /// <typeparam name="T">泛型类型</typeparam> /// <param name="sdr">游标</param> /// <returns></returns> private List<T> CreateInstanceListOfSqlDataReader<T>(SqlDataReader sdr) { List<T> tList = new List<T>(); while (sdr.Read()) { T t = CreateInstance<T>(sdr); tList.Add(t); } return tList; } } }
BaseDao写好以后我们就可以看看效果了,接下来我们创建一个UserInfoDao,来继承BaseDao,代码如下:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Test { public class UserInfoDao:BaseDao<EUserInfo>{} }
然后我们就可以开始测试了,下面是测试代码:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Test { class Program { static void Main(string[] args) { UserInfoDao userInfoDao = new UserInfoDao(); List<EUserInfo> userInfoList = userInfoDao.GetAll(); foreach (EUserInfo userInfo in userInfoList) { Console.WriteLine(userInfo); } Console.ReadKey(); } } }
这里我们可以直接调用BaseDao的GetAll方法,sql会自动在BaseDao中帮我们拼装好,得到的结果如下:
这里我们可以看见的效果是BaseDao帮我们把数据库中表的数据封装到了对象中.不需要我们手动的来进行实例化赋值,希望这个Demo能对初学反射的有点启发,有什么不足之处大家多多指教.
标签：adapter ext 入门 val list except value space reading
原文地址：http://www.cnblogs.com/zze46/p/6871965.html
