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基于Dapper二次封装了一个易用的ORM工具类,继承

发布时间:2019-10-28 22:04编辑:编程浏览(136)

    关于开发者的技术水平到底该如何定义,到底一个人的技术水平应该定位在高、中、低的标准是什么呢?很多人觉得这是一个仁者见仁的问题,有人觉得根据公司的那个员工等级判断。答案是肯定不是,从纯开发技术的角度来分析。很多人觉得自己一门语言精通了就去学其他语言了,美其名曰集大成者,这样的工作十几年却是初级水平的技术人员也不少。

    基于Dapper二次封装了一个易用的ORM工具类:SqlDapperUtil,把日常能用到的各种CRUD都进行了简化封装,让普通程序员只需关注业务即可,因为非常简单,故直接贴源代码,大家若需使用可以直接复制到项目中,该SqlDapperUtil已广泛用于公司项目中。

    在现有类(基类、父类)上建立新类(派生类、子类)的处理过程称为继承。派生类能自动获得基类的除了构造函数和析构函数以外的所有成员,可以在派生类中添加新的属性和方法扩展其功能。

    下面我来讲讲我的认知,C#这门技术到底学到什么程度可以进入到什么级别。

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using Dapper;
    using System.Data;
    using System.Data.Common;
    using System.Reflection;
    using System.IO;
    using System.Collections.Concurrent;
    using System.Data.SqlClient;
    
    namespace Zuowj.Common
    {
        /// <summary>
        /// 基于Dapper的数据操作类封装的工具类
        /// Author:左文俊
        /// Date:2017/12/11
        /// </summary>
        public class SqlDapperUtil
        {
            private static string dbConnectionStringConfigPath = null;
            private readonly static ConcurrentDictionary<string, bool> dbConnNamesCacheDic = new ConcurrentDictionary<string, bool>();
    
            private string dbConnectionName = null;
            private string dbConnectionString = null;
            private string dbProviderName = null;
            private IDbConnection dbConnection = null;
            private bool useDbTransaction = false;
            private IDbTransaction dbTransaction = null;
    
    
            #region 私有方法
    
            private IDbConnection GetDbConnection()
            {
                bool needCreateNew = false;
                if (dbConnection == null || string.IsNullOrWhiteSpace(dbConnection.ConnectionString))
                {
                    needCreateNew = true;
                }
                else if (!MemoryCacheUtil.Contains(dbConnectionName))
                {
                    needCreateNew = true;
                }
    
                if (needCreateNew)
                {
                    dbConnectionString = GetDbConnectionString(dbConnectionName, out dbProviderName);
                    var dbProviderFactory = DbProviderFactories.GetFactory(dbProviderName);
                    dbConnection = dbProviderFactory.CreateConnection();
                    dbConnection.ConnectionString = dbConnectionString;
                }
    
                if (dbConnection.State == ConnectionState.Closed)
                {
                    dbConnection.Open();
                }
    
                return dbConnection;
            }
    
            private string GetDbConnectionString(string dbConnName, out string dbProviderName)
            {
                //如果指定的连接字符串配置文件路径,则创建缓存依赖,一旦配置文件更改就失效,再重新读取
                string[] connInfos = MemoryCacheUtil.GetOrAddCacheItem(dbConnName, () =>
                {
                    var connStrSettings = ConfigUtil.GetConnectionStringForConfigPath(dbConnName, SqlDapperUtil.DbConnectionStringConfigPath);
                    string dbProdName = connStrSettings.ProviderName;
                    string dbConnStr = connStrSettings.ConnectionString;
                    //LogUtil.Info(string.Format("SqlDapperUtil.GetDbConnectionString>读取连接字符串配置节点[{0}]:{1},ProviderName:{2}", dbConnName, dbConnStr, dbProdName), "SqlDapperUtil.GetDbConnectionString");
                    return new[] { EncryptUtil.Decrypt(dbConnStr), dbProdName };
                }, SqlDapperUtil.DbConnectionStringConfigPath);
    
                dbProviderName = connInfos[1];
                return connInfos[0];
            }
    
    
            private T UseDbConnection<T>(Func<IDbConnection, T> queryOrExecSqlFunc)
            {
                IDbConnection dbConn = null;
    
                try
                {
                    Type modelType = typeof(T);
                    var typeMap = Dapper.SqlMapper.GetTypeMap(modelType);
                    if (typeMap == null || !(typeMap is ColumnAttributeTypeMapper<T>))
                    {
                        Dapper.SqlMapper.SetTypeMap(modelType, new ColumnAttributeTypeMapper<T>());
                    }
    
                    dbConn = GetDbConnection();
                    if (useDbTransaction && dbTransaction == null)
                    {
                        dbTransaction = GetDbTransaction();
                    }
    
                    return queryOrExecSqlFunc(dbConn);
                }
                catch
                {
                    throw;
                }
                finally
                {
                    if (dbTransaction == null && dbConn != null)
                    {
                        CloseDbConnection(dbConn);
                    }
                }
            }
    
            private void CloseDbConnection(IDbConnection dbConn, bool disposed = false)
            {
                if (dbConn != null)
                {
                    if (disposed && dbTransaction != null)
                    {
                        dbTransaction.Rollback();
                        dbTransaction.Dispose();
                        dbTransaction = null;
                    }
    
                    if (dbConn.State != ConnectionState.Closed)
                    {
                        dbConn.Close();
                    }
                    dbConn.Dispose();
                    dbConn = null;
                }
            }
    
            /// <summary>
            /// 获取一个事务对象(如果需要确保多条执行语句的一致性,必需使用事务)
            /// </summary>
            /// <param name="il"></param>
            /// <returns></returns>
            private IDbTransaction GetDbTransaction(IsolationLevel il = IsolationLevel.Unspecified)
            {
                return GetDbConnection().BeginTransaction(il);
            }
    
            private DynamicParameters ToDynamicParameters(Dictionary<string, object> paramDic)
            {
                return new DynamicParameters(paramDic);
            }
    
            #endregion
    
            public static string DbConnectionStringConfigPath
            {
                get
                {
                    if (string.IsNullOrEmpty(dbConnectionStringConfigPath))//如果没有指定配置文件,则取默认的配置文件路径作为缓存依赖路径
                    {
                        dbConnectionStringConfigPath = BaseUtil.GetConfigPath();
                    }
    
                    return dbConnectionStringConfigPath;
                }
                set
                {
                    if (!string.IsNullOrWhiteSpace(value) && !File.Exists(value))
                    {
                        throw new FileNotFoundException("指定的DB连接字符串配置文件不存在:" + value);
                    }
    
                    //如果配置文件改变,则可能导致连接字符串改变,故必需清除所有连接字符串的缓存以便后续重新加载字符串
                    if (!string.Equals(dbConnectionStringConfigPath, value, StringComparison.OrdinalIgnoreCase))
                    {
                        foreach (var item in dbConnNamesCacheDic)
                        {
                            MemoryCacheUtil.RemoveCacheItem(item.Key);
                        }
                    }
    
                    dbConnectionStringConfigPath = value;
                }
            }
    
            public SqlDapperUtil(string connName)
            {
                dbConnectionName = connName;
                if (!dbConnNamesCacheDic.ContainsKey(connName)) //如果静态缓存中没有,则加入到静态缓存中
                {
                    dbConnNamesCacheDic[connName] = true;
                }
    
            }
    
    
            /// <summary>
            /// 使用事务
            /// </summary>
            public void UseDbTransaction()
            {
                useDbTransaction = true;
            }
    
    
            /// <summary>
            /// 获取一个值,param可以是SQL参数也可以是匿名对象
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public T GetValue<T>(string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null)
            {
                return UseDbConnection((dbConn) =>
                 {
                     return dbConn.ExecuteScalar<T>(sql, param, dbTransaction, commandTimeout, commandType);
                 });
            }
    
            /// <summary>
            /// 获取第一行的所有值,param可以是SQL参数也可以是匿名对象
            /// </summary>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public Dictionary<string, dynamic> GetFirstValues(string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null)
            {
                return UseDbConnection((dbConn) =>
                {
                    Dictionary<string, dynamic> firstValues = new Dictionary<string, dynamic>();
                    List<string> indexColNameMappings = new List<string>();
                    int rowIndex = 0;
                    using (var reader = dbConn.ExecuteReader(sql, param, dbTransaction, commandTimeout, commandType))
                    {
                        while (reader.Read())
                        {
                            if ((++rowIndex) > 1) break;
                            if (indexColNameMappings.Count == 0)
                            {
                                for (int i = 0; i < reader.FieldCount; i++)
                                {
                                    indexColNameMappings.Add(reader.GetName(i));
                                }
                            }
    
                            for (int i = 0; i < reader.FieldCount; i++)
                            {
                                firstValues[indexColNameMappings[i]] = reader.GetValue(i);
                            }
                        }
                        reader.Close();
                    }
    
                    return firstValues;
    
                });
            }
    
            /// <summary>
            /// 获取一个数据模型实体类,param可以是SQL参数也可以是匿名对象
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public T GetModel<T>(string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null) where T : class
            {
                return UseDbConnection((dbConn) =>
                {
                    return dbConn.QueryFirstOrDefault<T>(sql, param, dbTransaction, commandTimeout, commandType);
                });
            }
    
            /// <summary>
            /// 获取符合条件的所有数据模型实体类列表,param可以是SQL参数也可以是匿名对象
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="buffered"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public List<T> GetModelList<T>(string sql, object param = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null) where T : class
            {
                return UseDbConnection((dbConn) =>
                {
                    return dbConn.Query<T>(sql, param, dbTransaction, buffered, commandTimeout, commandType).ToList();
                });
            }
    
            /// <summary>
            /// 获取符合条件的所有数据并根据动态构建Model类委托来创建合适的返回结果(适用于临时性结果且无对应的模型实体类的情况)
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="buildModelFunc"></param>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="buffered"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public T GetDynamicModel<T>(Func<IEnumerable<dynamic>, T> buildModelFunc, string sql, object param = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null)
            {
                var dynamicResult = UseDbConnection((dbConn) =>
               {
                   return dbConn.Query(sql, param, dbTransaction, buffered, commandTimeout, commandType);
               });
    
                return buildModelFunc(dynamicResult);
            }
    
            /// <summary>
            /// 获取符合条件的所有指定返回结果对象的列表(复合对象【如:1对多,1对1】),param可以是SQL参数也可以是匿名对象
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="sql"></param>
            /// <param name="types"></param>
            /// <param name="map"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="buffered"></param>
            /// <param name="splitOn"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
    
            public List<T> GetMultModelList<T>(string sql, Type[] types, Func<object[], T> map, object param = null, bool buffered = true, string splitOn = "Id", int? commandTimeout = null, CommandType? commandType = null)
            {
                return UseDbConnection((dbConn) =>
                {
                    return dbConn.Query<T>(sql, types, map, param, dbTransaction, buffered, splitOn, commandTimeout, commandType).ToList();
                });
            }
    
    
    
    
            /// <summary>
            /// 执行SQL命令(CRUD),param可以是SQL参数也可以是要添加的实体类
            /// </summary>
            /// <param name="sql"></param>
            /// <param name="param"></param>
            /// <param name="transaction"></param>
            /// <param name="commandTimeout"></param>
            /// <param name="commandType"></param>
            /// <returns></returns>
            public bool ExecuteCommand(string sql, object param = null, int? commandTimeout = null, CommandType? commandType = null)
            {
                return UseDbConnection((dbConn) =>
                {
                    int result = dbConn.Execute(sql, param, dbTransaction, commandTimeout, commandType);
                    return (result > 0);
                });
            }
    
            /// <summary>
            /// 批量转移数据(利用SqlBulkCopy实现快速大批量插入到指定的目的表及SqlDataAdapter的批量删除)
            /// </summary>
            public bool BatchMoveData(string srcSelectSql, string srcTableName, List<SqlParameter> srcPrimarykeyParams, string destConnName, string destTableName)
            {
    
                using (SqlDataAdapter srcSqlDataAdapter = new SqlDataAdapter(srcSelectSql, GetDbConnectionString(dbConnectionName, out dbProviderName)))
                {
                    DataTable srcTable = new DataTable();
                    SqlCommand deleteCommand = null;
                    try
                    {
                        srcSqlDataAdapter.AcceptChangesDuringFill = true;
                        srcSqlDataAdapter.AcceptChangesDuringUpdate = false;
                        srcSqlDataAdapter.Fill(srcTable);
    
                        if (srcTable == null || srcTable.Rows.Count <= 0) return true;
    
                        string notExistsDestSqlWhere = null;
                        string deleteSrcSqlWhere = null;
    
                        for (int i = 0; i < srcPrimarykeyParams.Count; i++)
                        {
                            string keyColName = srcPrimarykeyParams[i].ParameterName.Replace("@", "");
                            notExistsDestSqlWhere += string.Format(" AND told.{0}=tnew.{0}", keyColName);
                            deleteSrcSqlWhere += string.Format(" AND {0}=@{0}", keyColName);
                        }
    
                        string dbProviderName2 = null;
                        using (var destConn = new SqlConnection(GetDbConnectionString(destConnName, out dbProviderName2)))
                        {
                            destConn.Open();
    
                            string tempDestTableName = "#temp_" + destTableName;
                            destConn.Execute(string.Format("select top 0 * into {0} from {1}", tempDestTableName, destTableName));
                            string destInsertCols = null;
                            using (var destSqlBulkCopy = new SqlBulkCopy(destConn))
                            {
                                try
                                {
                                    destSqlBulkCopy.BulkCopyTimeout = 120;
                                    destSqlBulkCopy.DestinationTableName = tempDestTableName;
                                    foreach (DataColumn col in srcTable.Columns)
                                    {
                                        destSqlBulkCopy.ColumnMappings.Add(col.ColumnName, col.ColumnName);
                                        destInsertCols += "," + col.ColumnName;
                                    }
    
                                    destSqlBulkCopy.BatchSize = 1000;
                                    destSqlBulkCopy.WriteToServer(srcTable);
                                }
                                catch (Exception ex)
                                {
                                    //LogUtil.Error("SqlDapperUtil.BatchMoveData.SqlBulkCopy:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
                                }
    
                                destInsertCols = destInsertCols.Substring(1);
    
                                destConn.Execute(string.Format("insert into {1}({0}) select {0} from {2} tnew where not exists(select 1 from {1} told where {3})",
                                                 destInsertCols, destTableName, tempDestTableName, notExistsDestSqlWhere.Trim().Substring(3)), null, null, 100);
                            }
                            destConn.Close();
                        }
    
                        deleteCommand = new SqlCommand(string.Format("DELETE FROM {0} WHERE {1}", srcTableName, deleteSrcSqlWhere.Trim().Substring(3)), srcSqlDataAdapter.SelectCommand.Connection);
                        deleteCommand.Parameters.AddRange(srcPrimarykeyParams.ToArray());
                        deleteCommand.UpdatedRowSource = UpdateRowSource.None;
                        deleteCommand.CommandTimeout = 200;
    
                        srcSqlDataAdapter.DeleteCommand = deleteCommand;
                        foreach (DataRow row in srcTable.Rows)
                        {
                            row.Delete();
                        }
    
                        srcSqlDataAdapter.UpdateBatchSize = 1000;
                        srcSqlDataAdapter.Update(srcTable);
                        srcTable.AcceptChanges();
    
                        return true;
                    }
                    catch (Exception ex)
                    {
                        //LogUtil.Error("SqlDapperUtil.BatchMoveData:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
                        return false;
                    }
                    finally
                    {
                        if (deleteCommand != null)
                        {
                            deleteCommand.Parameters.Clear();
                        }
                    }
                }
    
            }
    
            /// <summary>
            /// 批量复制数据(把源DB中根据SQL语句查出的结果批量COPY插入到目的DB的目的表中)
            /// </summary>
            public TResult BatchCopyData<TResult>(string srcSelectSql, string destConnName, string destTableName, IDictionary<string, string> colMappings, Func<IDbConnection, TResult> afterCoppyFunc)
            {
    
                using (SqlDataAdapter srcSqlDataAdapter = new SqlDataAdapter(srcSelectSql, GetDbConnectionString(dbConnectionName, out dbProviderName)))
                {
                    DataTable srcTable = new DataTable();
                    TResult copyResult = default(TResult);
                    try
                    {
                        srcSqlDataAdapter.AcceptChangesDuringFill = true;
                        srcSqlDataAdapter.AcceptChangesDuringUpdate = false;
                        srcSqlDataAdapter.Fill(srcTable);
    
                        if (srcTable == null || srcTable.Rows.Count <= 0) return copyResult;
    
    
                        string dbProviderName2 = null;
                        using (var destConn = new SqlConnection(GetDbConnectionString(destConnName, out dbProviderName2)))
                        {
                            destConn.Open();
                            string tempDestTableName = "#temp_" + destTableName;
                            destConn.Execute(string.Format("select top 0 * into {0} from {1}", tempDestTableName, destTableName));
                            bool bcpResult = false;
                            using (var destSqlBulkCopy = new SqlBulkCopy(destConn))
                            {
                                try
                                {
                                    destSqlBulkCopy.BulkCopyTimeout = 120;
                                    destSqlBulkCopy.DestinationTableName = tempDestTableName;
                                    foreach (var col in colMappings)
                                    {
                                        destSqlBulkCopy.ColumnMappings.Add(col.Key, col.Value);
                                    }
    
                                    destSqlBulkCopy.BatchSize = 1000;
                                    destSqlBulkCopy.WriteToServer(srcTable);
                                    bcpResult = true;
                                }
                                catch (Exception ex)
                                {
                                    //LogUtil.Error("SqlDapperUtil.BatchMoveData.SqlBulkCopy:" + ex.ToString(), "SqlDapperUtil.BatchMoveData");
                                }
                            }
    
                            if (bcpResult)
                            {
                                copyResult = afterCoppyFunc(destConn);
                            }
    
                            destConn.Close();
                        }
    
                        return copyResult;
                    }
                    catch (Exception ex)
                    {
                        //LogUtil.Error("SqlDapperUtil.BatchCopyData:" + ex.ToString(), "SqlDapperUtil.BatchCopyData");
                        return copyResult;
                    }
                }
    
            }
    
    
            /// <summary>
            /// 当使用了事务,则最后需要调用该方法以提交所有操作
            /// </summary>
            /// <param name="dbTransaction"></param>
            public void Commit()
            {
                try
                {
                    if (dbTransaction.Connection != null && dbTransaction.Connection.State != ConnectionState.Closed)
                    {
                        dbTransaction.Commit();
                    }
                }
                catch
                {
                    throw;
                }
                finally
                {
                    if (dbTransaction.Connection != null)
                    {
                        CloseDbConnection(dbTransaction.Connection);
                    }
                    dbTransaction.Dispose();
                    dbTransaction = null;
                    useDbTransaction = false;
    
                    if (dbConnection != null)
                    {
                        CloseDbConnection(dbConnection);
                    }
                }
            }
    
            /// <summary>
            /// 当使用了事务,如果报错或需要中断执行,则需要调用该方法执行回滚操作
            /// </summary>
            /// <param name="dbTransaction"></param>
            public void Rollback()
            {
                try
                {
                    if (dbTransaction.Connection != null && dbTransaction.Connection.State != ConnectionState.Closed)
                    {
                        dbTransaction.Rollback();
                    }
                }
                catch
                {
                    throw;
                }
                finally
                {
                    if (dbTransaction.Connection != null)
                    {
                        CloseDbConnection(dbTransaction.Connection);
                    }
    
                    dbTransaction.Dispose();
                    dbTransaction = null;
                    useDbTransaction = false;
                }
            }
    
            ~SqlDapperUtil()
            {
                try
                {
                    CloseDbConnection(dbConnection, true);
                }
                catch
                { }
            }
    
        }
    }
    

    继承的特性:

    我常说C#的入门技术是委托、事件、消息。只有当你可以纯熟运用这三个技能的时候,才刚刚入门,此时C#的大门才算正式为你打开。很多人在学了一些语法编写一些项目后就觉得C#精通了,其实你们还没入门呢(对日开发的居多)

    ColumnAttributeTypeMapper辅助类相关代码如下:(如果不考虑实体类的属性与表字段不一致的情况,如下映射类可以不需要添加,同时SqlDapperUtil中移除相关依赖ColumnAttributeTypeMapper逻辑即可)

    可传递性:C从B派生,B从A派生,那么C不仅继承B也继承A。

    下面上一个图片,大家来看看自己的定位,当然是纯技术角度,其实,有些时候一个软件架构,用初级软件工程师也是可以架构的。

    using Dapper;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Reflection;
    using System.Text;
    using System.Threading.Tasks;
    
    namespace KYExpress.Common
    {
        public class ColumnAttributeTypeMapper<T> : FallbackTypeMapper
        {
            public ColumnAttributeTypeMapper()
                : base(new SqlMapper.ITypeMap[]
                    {
                        new CustomPropertyTypeMap(
                           typeof(T),
                           (type, columnName) =>
                               type.GetProperties().FirstOrDefault(prop =>
                                   prop.GetCustomAttributes(false)
                                       .OfType<ColumnAttribute>()
                                       .Any(attr => attr.Name == columnName)
                                   )
                           ),
                        new DefaultTypeMap(typeof(T))
                    })
            {
            }
        }
    
        [AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
        public class ColumnAttribute : Attribute
        {
            public string Name { get; set; }
        }
    
        public class FallbackTypeMapper : SqlMapper.ITypeMap
        {
            private readonly IEnumerable<SqlMapper.ITypeMap> _mappers;
    
            public FallbackTypeMapper(IEnumerable<SqlMapper.ITypeMap> mappers)
            {
                _mappers = mappers;
            }
    
    
            public ConstructorInfo FindConstructor(string[] names, Type[] types)
            {
                foreach (var mapper in _mappers)
                {
                    try
                    {
                        ConstructorInfo result = mapper.FindConstructor(names, types);
                        if (result != null)
                        {
                            return result;
                        }
                    }
                    catch (NotImplementedException)
                    {
                    }
                }
                return null;
            }
    
            public SqlMapper.IMemberMap GetConstructorParameter(ConstructorInfo constructor, string columnName)
            {
                foreach (var mapper in _mappers)
                {
                    try
                    {
                        var result = mapper.GetConstructorParameter(constructor, columnName);
                        if (result != null)
                        {
                            return result;
                        }
                    }
                    catch (NotImplementedException)
                    {
                    }
                }
                return null;
            }
    
            public SqlMapper.IMemberMap GetMember(string columnName)
            {
                foreach (var mapper in _mappers)
                {
                    try
                    {
                        var result = mapper.GetMember(columnName);
                        if (result != null)
                        {
                            return result;
                        }
                    }
                    catch (NotImplementedException)
                    {
                    }
                }
                return null;
            }
    
    
            public ConstructorInfo FindExplicitConstructor()
            {
                return _mappers
                    .Select(mapper => mapper.FindExplicitConstructor())
                    .FirstOrDefault(result => result != null);
            }
        }
    
    }
    

    单一性:只能从一个基类中继承,不能同时继承多个基类继承中的访问修饰符base和this关键字基类的构造函数和析构函数不能被继承的。但可以使用关键字base来继承基类的构造函数。

      图片 1

    使用示例方法如下:

    C#中的base关键字代表基类,使用base关键字可以调用基类的构造函数、属性和方法。

     

     1.先来模拟各种查询数据(由于是直接写模拟SQL输出,故没有条件,也便于大家COPY后直接可以测试结果)

    namespace InheritanceApplication
    {
       class Shape 
       {
          public void setWidth(int w)
          {
             width = w;
          }
          public void setHeight(int h)
          {
             height = h;
          }
          protected int width;
          protected int height;
       }
    
       // 派生类
       class Rectangle: Shape
       {
          public int getArea()
          { 
             return (width * height); 
          }
       }
    
       class RectangleTester
       {
          static void Main(string[] args)
          {
             Rectangle Rect = new Rectangle();
    
             Rect.setWidth(5);
             Rect.setHeight(7);
    
             // 打印对象的面积
             Console.WriteLine("总面积: {0}",  Rect.getArea());
             Console.ReadKey();
          }
       }
    }
    

    1,        comom language runtime :初级人员无视他,中级人员起码要知道他,高级人员多数要会使用其中一些应用比如security,架构师要理解原理。

                //实例化SqlDapperUtil对象,构造函数是config文件中的connectionStrings的Name名
                var dapper = new SqlDapperUtil("LmsConnectionString");
    
                //查询1个值
                DateTime nowTime = dapper.GetValue<DateTime>("select getdate() as nowtime");
    
    
                //查询1行值,并转换成字典(这对于临时查询多个字段而无需定义实体类有用)
                Dictionary<string, dynamic> rowValues = dapper.GetFirstValues("select 0 as col0,1 as col1,2 as col2");
    
    
                //查询1行并返回实体类
                Person person = dapper.GetModel<Person>("select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr");
    
    
                //查询1行表字段与实体类属性不一致映射
                Person person2 = dapper.GetModel<Person>("select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddress");
    
    
                //查询多行返回实体集合
                var persons = dapper.GetModelList<Person>(@"select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
                                                                                select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
                                                                                select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress
                                                                            ");
    
    
                //查询多行返回1对1关联实体结果集
                var personWithCarResult = dapper.GetMultModelList<Person>(@"select t1.*,t2.* from
                                                                                                        (select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
                                                                                                        select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
                                                                                                        select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress)as t1 inner join
                                                                                                        (
                                                                                                        select '张三' as DriverName,'大众' as Brand,'2018-8-8' as ManufactureDate union all
                                                                                                        select '李四' as DriverName,'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
                                                                                                        select '王五' as DriverName,'奥迪' as Brand,'2017-8-8' as ManufactureDate
                                                                                                        )as t2
                                                                                                        on t1.Name=t2.DriverName
                                                                            ", new[] { typeof(Person), typeof(CarInfo) }, (objs) =>
                                                                             {
                                                                                 Person personItem = objs[0] as Person;
                                                                                 CarInfo carItem = objs[1] as CarInfo;
                                                                                 personItem.Car = carItem;
                                                                                 return personItem;
                                                                             }, splitOn: "DriverName");
    
    
    
    
                //查询多行返回1对多关联实体结果=personWithManyCars
                List<Person> personWithManyCars = new List<Person>();
                dapper.GetMultModelList<Person>(@"select t1.*,t2.* from
                                                                                                        (select '张三' as Name,22 as Age,'2018-1-1' as BirthDay,'中国广东深圳' as HomeAddr union all
                                                                                                        select '李四' as Name,25 as Age,'2018-10-1' as BirthDay,'中国广东深圳' as HomeAddress union all
                                                                                                        select '王五' as Name,35 as Age,'1982-10-1' as BirthDay,'中国广东广州' as HomeAddress)as t1 inner join
                                                                                                        (
                                                                                                        select '张三' as DriverName,'大众' as Brand,'2018-8-8' as ManufactureDate union all
                                                                                                        select '张三' as DriverName,'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
                                                                                                        select '张三' as DriverName,'奥迪' as Brand,'2017-8-8' as ManufactureDate
                                                                                                        )as t2
                                                                                                        on t1.Name=t2.DriverName
                                                                            ", new[] { typeof(Person), typeof(CarInfo) }, (objs) =>
                                                                            {
                                                                                Person personItem = objs[0] as Person;
                                                                                CarInfo carItem = objs[1] as CarInfo;
    
                                                                                Person personItemMain = personWithManyCars.FirstOrDefault(p => p.Name == personItem.Name);
                                                                                if (personItemMain == null)
                                                                                {
                                                                                    personItem.Cars = new List<CarInfo>();
                                                                                    personItemMain = personItem;
                                                                                    personWithManyCars.Add(personItemMain);
                                                                                }
    
                                                                                personItemMain.Cars.Add(carItem);
                                                                                return personItemMain;
    
                                                                            }, splitOn: "DriverName");
    

     

    2,        .netframework :这里有许多框架,会的越多越好。

    2.下面是演示如何进行增、删、改以及动态查询的情况:

    3,        Base class library :这里都是基本语法你会了多少呢,想成为高手一定要全部学会,一个都不能丢。

                //使用事务创建多张表,多条SQL语句写在一起
                try
                {
                    dapper.UseDbTransaction();
                    dapper.ExecuteCommand(@"create table T_Person(Name nvarchar(20) primary key,Age int,BirthDay datetime,HomeAddress nvarchar(200));
                                                        create table T_CarInfo(DriverName nvarchar(20) primary key,Brand nvarchar(50),ManufactureDate datetime)");
                    dapper.Commit();
                }
                catch (Exception ex)
                {
                    dapper.Rollback();
                    //记日志
                }
    
                //使用事务批量插入多张表的多个记录,多条SQL分多次执行(参数支持批量集合对象传入,无需循环)
                try
                {
                    dapper.UseDbTransaction();
                    dapper.ExecuteCommand(@"insert into T_Person
    select N'张三' as Name,22 as Age,'2018-1-1' as BirthDay,N'中国广东深圳' as HomeAddress union all
    select N'李四' as Name,25 as Age,'2018-10-1' as BirthDay,N'中国广东深圳' as HomeAddress union all
    select N'王五' as Name,35 as Age,'1982-10-1' as BirthDay,N'中国广东广州' as HomeAddress");
    
    
                    var carInfos = dapper.GetModelList<CarInfo>(@"
    select N'张三' as DriverName,N'大众' as Brand,'2018-8-8' as ManufactureDate union all
    select N'李四' as DriverName,N'奔驰' as Brand,'2018-1-8' as ManufactureDate union all
    select N'王五' as DriverName,N'奥迪' as Brand,'2017-8-8' as ManufactureDate");
    
                    dapper.ExecuteCommand(@"insert into T_CarInfo(DriverName,Brand,ManufactureDate) Values(@DriverName,@Brand,@ManufactureDate)", carInfos);
    
                    dapper.Commit();
                }
                catch (Exception ex)
                {
                    dapper.Rollback();
                    //记日志
                }
    
                //执行删除,有参数,参数可以是实体类、匿名对象、字典(如有需要,可以是集合,以支持批量操作)
                bool deleteResult = dapper.ExecuteCommand("delete from T_CarInfo where DriverName=@DriverName", new { DriverName = "李四" });
    
                //构建动态执行SQL语句(以下是更新,查询类似)
                StringBuilder updateSqlBuilder = new StringBuilder();
                var updateParams = new Dictionary<string, object>();
    
                if (1 == 1)
                {
                    updateSqlBuilder.Append(",Age=@Age");
                    updateParams["Age"] = 20;
                }
    
                if (2 == 2)
                {
                    updateSqlBuilder.Append(",BirthDay=@BirthDay");
                    updateParams["BirthDay"] = Convert.ToDateTime("2010-1-1");
                }
    
                if (3 == 3)
                {
                    updateSqlBuilder.Append(",HomeAddress=@HomeAddress");
                    updateParams["HomeAddress"] = "中国北京天安门";
                }
    
                string updateSql = string.Concat("update T_Person set ", updateSqlBuilder.ToString().TrimStart(','), "  where  Name=@Name");
                updateParams["Name"] = "张三";
    
                bool updateResult = dapper.ExecuteCommand(updateSql, updateParams);
    
                //查询返回动态自定义结果,之所以不直接返回Dynamic就好,是因为可读性差,故尽可能的在执行后就转成指定的类型
                Tuple<string, int> hasCarInfo = dapper.GetDynamicModel<Tuple<string, int>>((rs) =>
                {
                    var result = rs.First();
                    return Tuple.Create<string, int>(result.Name, result.CarCount);
                }, @"select a.Name,count(b.DriverName) as CarCount from T_Person a left join T_CarInfo b on a.Name=b.DriverName where a.Name=@Name group by a.Name", new { Name = "张三" });
    

    4,        Runtime infrastructure library:这里内容初级开发者不用了解,进入中级就要开始一点点吸收了,想到高级要全部消化,是全部哦。

    3.还有两个方法:BatchCopyData、BatchMoveData,这是特殊封装的,不是基于Dapper而是基于原生的Ado.net及BCP,目的是快速大量跨DB跨表COPY数据或转移数据,使用也不复杂,建议想了解的网友可以查看我以往的文章

    5,        Framework calss library:这里都是基本应用,初级程序员肯能都会接触一些,中级就会了解和运用一些,高级就要全部会用。

    以上示例方法用到了两个类,如下:

    6,        Core concepts:这里的内容同上。

            class Person
            {
                public string Name { get; set; }
    
    
                public int Age { get; set; }
    
                public DateTime BirthDay { get; set; }
    
                [Column(Name = "HomeAddress")]
                public string HomeAddr { get; set; }
    
                public CarInfo Car { get; set; }
    
                public List<CarInfo> Cars { get; set; }
            }
    
            class CarInfo
            {
                public string Brand { get; set; }
    
                public DateTime ManufactureDate { get; set; }
    
                public string DriverName { get; set; }
            }
    

    7,        Core features,core objects,CLI language,DLR略过。。。

    SqlDapperUtil类中依赖了之前我封装的类:如:MemoryCacheUtil(本地内存依赖缓存实用工具类)、ConfigUtil(配置文件管理工具类)、EncryptUtil(加密工具类),如果项目中不想引用这些类,可以移除或改成其它方法即可。

    本文由金沙国际官网发布于编程,转载请注明出处:基于Dapper二次封装了一个易用的ORM工具类,继承

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