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 ) not null,
UserName ) not null,
UserPwd ) not null,
Gender ) check(Gender in ('男','女'))
)
go
','男')
','男')
','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);
/////////////////
;
}
/// <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.