ado.net快速学习实践篇（二）

我们接着上文继续完成我们的ado.net简单实践。

五、dal层数据访问实现【示例代码】

在这里我们使用前一篇文章里实现的数据持久化层和伪SqlMapper对象，实现数据操作。下面我们来看看Dal下核心的Dao如何实现：

还记得我们在IBatis.net下面的dao类是怎么实现的吗？没错，我们根据一个基类BaseDAO和它的构造函数，实现dao的配置加载。但是楼猪的实现没有那么复杂和强大，本文的实现其实就是通过BaseDAO和构造函数获取数据库连接对象的key，初始化一个SqlMapper，然后利用SqlMapper对象进行基本的CRUD等等数据操作。那么我们如何利用BaseDAO和构造函数就像以前在IBatis.net系列文章里的提到的Dal层下那样进行SqlMapper的初始化呢？

1、在AdoNetDataAccess.Mapper下我们定义公共的BaseDAO类

namespace AdoNetDataAccess.Mapper
{
 public abstract class BaseDAO
 {
 #region Properties

 public SqlMapper SqlMapper { get; set; }

 #endregion

 #region Constructor

 private BaseDAO()
 {
 }

 /// <summary>
 /// SqlMapper属性适用
 /// </summary>
 /// <param name="mapperName"></param>
 public BaseDAO(string mapperName)
 {
 this.SqlMapper = MapperUtill.GetMapper(mapperName);
 }

 #endregion
 }
}

2、初始化SqlMapper的实用类

using System;
using System.Collections.Generic;
using System.Configuration;

namespace AdoNetDataAccess.Mapper
{
 using AdoNetDataAccess.Core.Contract;
 using AdoNetDataAccess.Core.Implement;

 public sealed class MapperUtill
 {
 #region fields

 public static string currentSqlKey = "sqlConn";

 public static int cmdTimeOut = 15;

 private static readonly object objSync = new object();

 private static readonly IDictionary<string, SqlMapper> dictMappers = new Dictionary<string, SqlMapper>();

 #endregion

 #region constructor and methods

 private MapperUtill()
 {

 }

 static MapperUtill()
 {
 try
 {
 cmdTimeOut = int.Parse(ConfigurationManager.AppSettings["db_timeOut"]);
 }
 catch
 {
 cmdTimeOut = 15;
 }
 //实例化SqlDbMapper
 for (int i = 0; i < ConfigurationManager.ConnectionStrings.Count; i++)
 {
 string key = ConfigurationManager.ConnectionStrings[i].Name;
 string value = ConfigurationManager.ConnectionStrings[i].ConnectionString;
 CreateMapper(key, value, cmdTimeOut);
 }
 }

 public static SqlMapper GetSqlMapper(string key)
 {
 return MapperUtill.GetMapper(key);
 }

 public static SqlMapper GetCurrentSqlMapper()
 {
 return MapperUtill.GetMapper(currentSqlKey);
 }

 public static void CreateMapper(string connKey, string sqlConStr, int connTimeOut)
 {
 IDbOperation operation = new SqlServer(sqlConStr, connTimeOut);
 SqlMapper mapper = new SqlMapper(operation);
 dictMappers.Add(connKey.ToUpper().Trim(), mapper);//不区分大小写
 }

 public static SqlMapper GetMapper(string sqlConKey)
 {
 if (string.IsNullOrEmpty(sqlConKey))
 {
 throw new Exception("数据库连接字符串主键为空!");
 }
 sqlConKey = sqlConKey.ToUpper();//不区分大小写
 SqlMapper mapper = null;
 if (dictMappers.ContainsKey(sqlConKey))
 {
 mapper = dictMappers[sqlConKey];
 }
 else
 {
 throw new Exception(string.Format("没有{0}所对应的数据库连接", sqlConKey));
 }
 return mapper;
 }

 /// <summary>
 /// 释放所有
 /// </summary>
 public void Release()
 {
 foreach (KeyValuePair<string, SqlMapper> kv in dictMappers)
 {
 SqlMapper mapper = kv.Value;
 if (mapper == null)
 {
 continue;
 }
 mapper.CurrentDbOperation.CloseConnection();
 }
 dictMappers.Clear();
 }

 #endregion

 }
}

这个实用类的重要作用就是初始化配置文件里connectionStrings配置节点，以获取sql连接对象必须的连接字符串。

3、PersonDao类

下面就是针对具体的Person表的数据操作了：

using System.Collections.Generic;
using System.Data;

namespace AdoNetDataAccess.Dal.Dao
{
 using AdoNetDataAccess.Dal.Model;
 using AdoNetDataAccess.Dal.Utility;
 using AdoNetDataAccess.Mapper;

 public class PersonDao : BaseDAO
 {
 public PersonDao()
 : base("sqlConn")//sqlConn是<connectionStrings>配置节点的一个name
 {
 }

 public int Insert(string sqlInsert)
 {
 int id = this.SqlMapper.Insert(sqlInsert);
 //object obj = this.SqlMapper.ExecuteScalar(sqlInsert, System.Data.CommandType.Text, null);
 return id;
 }

 public bool BatchInsert(IList<Person> listModels)
 {
 int batchSize = 50000;
 int copyTimeOut = 60;
 DataTable dt = DataTableHelper.CreateTable<Person>(listModels);
 bool flag = this.SqlMapper.BatchInsert(typeof(Person).Name, batchSize, copyTimeOut, dt);
 return flag;
 }

 public int Update(string sqlUpdate)
 {
 int result = this.SqlMapper.Update(sqlUpdate);
 return result;
 }

 public IList<Person> SelectPersons(string sqlSelect)
 {
 IList<Person> listPersons = this.SqlMapper.QueryForList<Person>(sqlSelect);
 return listPersons;
 }

 public IDictionary<int, Person> SelectDictPersons(string sqlSelect)
 {
 IDictionary<int, Person> dictPersons = this.SqlMapper.QueryForDictionary<int, Person>("Id", sqlSelect);
 return dictPersons;
 }

 public DataTable SelectPersonTable(string sqlSelect)
 {
 DataTable dt = this.SqlMapper.FillDataTable(sqlSelect, CommandType.Text, null);
 return dt;
 }

 public DataSet SelectPersonDataSet(string sqlSelect)
 {
 DataSet ds = this.SqlMapper.FillDataSet(sqlSelect, CommandType.Text, null);
 return ds;
 }

 public int Delete(string sqlDelete)
 {
 int result = this.SqlMapper.Delete(sqlDelete);
 return result;
 }

 }
}

到这里，一个dao类操作就实现了。然后我们按步就班实现对外调用的服务接口。在表现层调用吧。

六、表现层的调用
1、配置文件

<appSettings>
 <add key="db_timeOut" value="5000"/>
</appSettings>
<connectionStrings>
 <add name="sqlConn" connectionString="Data Source=.\sqlexpress; Initial Catalog=TestDb; User Id=sa; Password=123456;"/>
 <add name="sqlConnStr1" connectionString="Data Source=.\sqlexpress; Initial Catalog=TestDb; User Id=sa; Password=123456;"/>
 <add name="sqlConnStr2" connectionString="Data Source=.\sqlexpress; Initial Catalog=TestDb; User Id=sa; Password=123456;"/>
</connectionStrings>

其中，connectionString是必须的，如果没有，我们无法加载调用可用的SqlMapper。

2、CRUD操作测试

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;

namespace OOXXWebApp
{
 using AdoNetDataAccess.Dal;
 using AdoNetDataAccess.Dal.Model;

 public partial class _Default : System.Web.UI.Page
 {
 protected void Page_Load(object sender, EventArgs e)
 {
 if (!IsPostBack)
 {
 //增删改查测试
 string sqlInsert = "INSERT Person (FirstName,LastName,Weight,Height) VALUES( 'jeff','wong',70,180) SELECT @@IDENTITY FROM Person(NOLOCK)";
 string sqlUpdate = "UPDATE Person SET Height=178 WHERE Id=1";
 string sqlSelect = "SELECT TOP 100 * FROM Person(NOLOCK)";
 string sqlDelete = "DELETE Person WHERE Id>10 AND Id<100";

 IList<Person> listModels = new List<Person>();
 for (int i = 0; i < 500000; i++)
 {
 Person model = new Person();
 model.FirstName = "Jeff";
 model.LastName = "Wong";
 model.Weight = 70;
 model.Height = 180;
 listModels.Add(model);
 }

 Response.Write("Test Beginning ");

 int id = ServiceFactory.CreatePersonService().Add(sqlInsert);
 Response.Write(string.Format(" Insert and return id:{0}", id));

 bool flag = ServiceFactory.CreatePersonService().BatchInsert(listModels);
 Response.Write(string.Format(" Batch Insert {0}", flag ? "succeed" : "failed"));

 IList<Person> listPersons = ServiceFactory.CreatePersonService().GetPersons(sqlSelect);
 Response.Write(string.Format(" Select pesons and return persons:{0}", listPersons.Count));

 IDictionary<int, Person> dictPersons = ServiceFactory.CreatePersonService().GetDictPersons(sqlSelect);
 Response.Write(string.Format(" Select pesons and return dictionary persons:{0}", dictPersons.Count));

 DataTable dt = ServiceFactory.CreatePersonService().GetPersonTable(sqlSelect);
 Response.Write(string.Format(" Select pesons and return persons:{0}", dt.Rows.Count));

 DataSet ds = ServiceFactory.CreatePersonService().GetPersonDataSet(sqlSelect);
 Response.Write(string.Format(" Select pesons and return persons:{0}", ds.Tables[0].Rows.Count));

 int affectNum = ServiceFactory.CreatePersonService().Modify(sqlUpdate);
 Response.Write(string.Format(" Update and affect rows :{0}", affectNum));

 affectNum = 0;
 affectNum = ServiceFactory.CreatePersonService().Remove(sqlDelete);
 Response.Write(string.Format(" Delete and affect rows :{0}", affectNum));

 Response.Write(" Test End.");
 }
 }
 }
}

这个就不用多说了吧，表现层写SQL语句调用写好的服务就行了。比较不舒服的地方就是SQL语句不得不写在类里面，如果自动生成或者独立放在xml下实现可配置的形式那就更好了，当然sql语句不是我们讨论的重点，您有好的方法可以自己扩展实现更人性化的功能，减少书写SQLl语句的工作。

七、最后，对demo工程文件结构进行简单说明。
1、数据持久化层AdoNetDataAccess.Core
2、SqlMapper层AdoNetDataAccess.Mapper（引用AdoNetDataAccess.Core）
3、具体数据操作使用层AdoNetDataAccess.Dal（引用AdoNetDataAccess.Mapper）
4、表现层AdoNetDataAccessWebApp（引用AdoNetDataAccess.Dal）
可以看出，工程里的文件结构还是很清晰的，需要学习的童鞋不妨下载使用试试看吧。