图片 1

ColumnAttributeTypeMapper协助类相关代码如下:(如若不思考实体类的质量与表字段不平等的情形,如下映射类能够无需增添,同期SqlDapperUtil中移除相关信任ColumnAttributeTypeMapper逻辑就能够)

任何验证

1、上文中涉及“反射能够给只读字段进行赋值不过力不能支给只读属性进行赋值”。无法给只读属性进行赋值是因为尚未set访问器。可是大家早已知晓了足以给字段赋值,并且只读属性会生成隐蔽字段,那我们是或不是足以经过给隐蔽字段进展赋值直接到达给电动属性赋值的指标吧?答案是足以的!

定义User的只读自动属性

    public class User
    {
        public int age { get;  } = 1;
        public User()
        {
            age = 3;
        }
    }

调节台的反射赋值代码:

            var user = new User();
            try { typeof(User).GetProperty("age").SetValue(user, 9); }
            catch{    Console.WriteLine("只读属性赋值失败");}
            typeof(User).GetField("<age>k__BackingField", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(user,9);
            Console.WriteLine(user.age);
            Console.Read();

运行

图片 2

2、因为隐敝字段是私家的,所以取到掩瞒字段需求  BindingFlags.NonPublic

3、只读自动属性表达不想被访问到那为啥还要给它赋值呢?这几个难点……做着玩,项目中本人以为也未曾怎么用到的机会……

2、在python目录中筛选python.exe

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);
        }
    }

}

发端解释

通过C#扭转的IL中间语言代码能够精晓的更明亮

    public class User
    {
        public int id = 0;
        public int age { get; set; } = 1;
        public User()
        {
            id = 2;
            age = 3;
        }
    }

图片 3图片 4

能够见到,自动属性会生成多个称呼为 ‘<age>k__BackingField’
的遮盖私有字段+私有字段的get/set方法+属性代码段;

能够见到IL代码生成了User的构造函数
.ctor,ctor是构造函数(Constructor)。

任由直接赋值依然构造函数赋值,都是在.ctor中实行的,而且操作的都是字段,自动属性的赋值操作的是蒙蔽字段。

  public interface IUser
  {
    int id { get; set; }
  }

图片 5

能够看来,接口中的自动属性并不曾变化掩盖字段。

1、eclipse->windows->preferences

3.还可能有四个措施:BatchCopyData、BatchMoveData,那是特种封装的,不是依附Dapper而是基于原生的Ado.net及BCP,指标是高速大批量跨DB跨表COPY数据或撤换数据,使用也不复杂,提出想询问的网络亲密的朋友能够查阅本身过去的稿子

C#中字段、属性和构造函数赋值的主题素材

 

2.下边是亲自去做怎么着实行增、删、改以致动态查询的情状:

提议难点

先是提议多少个难点:

1、怎么样落到实处团结的流入框架?

2、字段和自动属性的分歧是怎么?

3、字段和机关属性注明时的直接赋值和构造函数赋值有啥样界别?

4、为何只读字段和只读自动属性(唯有get未有set访谈器)都能够在构造函数中实行赋值?

5、反射能够给只读字段或许只读属性进行赋值吗?

6、自动属性和常常属性的界别?

这么些题材是本身在试着写自身的注入实现时遇上的题目。这几个难点应有在念书C#时的第生机勃勃节课就应当学到了,笔者看英特网还恐怕有人享受说他在面试时遇相会试官问为啥只读字段和只读自动属性可以在构造函数中张开赋值,他从未回应上来,然后她写小说斟酌这一个主题材料,却未有得出叁个明显的答案,实在心痛。英特网关于只读属性有个别是写ReadOnly天性的,读到这几个小说直接跳过呢,老版本的C#近日看也没怎么帮衬。

 图片 6

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
            { }
        }

    }
}

交由答案

2、属性比字段多了get/set访谈器;字段是在内部存款和储蓄器中宣示的几个内存空间,能够真切的寄放值;属性像字段雷同使用,却得以有投机的代码段,能赋值取值,是因为访谈属性正是调用属性的get/set方法对字段进行取值赋值(大概不操作字段);在MSDN上,建议字段作为类的民用变量使用private/protected修饰,属性则往往作为共有属性使用public修饰;字段的读取和操作都以一贯操作内部存款和储蓄器,属性是调用get/set访谈器,所以字段比属性快。

3、正确来讲,未有分歧。分歧仅仅是直接赋值先举行,构造函数赋值后进行。在扭转的IL中间语言(C#代码先编写翻译成IL代码,然后才编译成汇编语言)中,字段直接赋值和构造函数赋值是在同八个代码段中(构造函数中)的。

4、其豆蔻年华题目得以和地点的难题生龙活虎并起来回答。构造函数作为实例化一个类的输入,是初次访问的。字段的直接赋值其实也是坐落构造函数中施行的,所以才说平昔赋值和构造函数赋值未有区分。“只读”的范围只是由C#编写翻译器(CLLX570)维护的,笔者觉着全名应该称为“除构造函数外只读”越发可信,那是C#语法的平整记住就行(那是自然,直接赋值其实是身处构造函数中张开赋值的,假设构造函数不可能赋值那只读字段未有值和未有声美素佳儿(Beingmate)样);

5、本条难题又有什么不可和方面包车型大巴主题材料联系起来共同回答。通过反射能够给自读字段赋值不过爱莫能助给只读属性进行赋值(不相信任的可以试一下)。对只读字段的赋值是因为绕过了C#编写翻译器(CLRubicon)的只读显示,对只读属性赋值的话是依然调用set访谈器对字段进行赋值,因为从没set访谈器所以同意后会报错。那么难点来了,那为何只读自动属性没有set访问器还足以在构造函数中赋值呢?其实只读自动属性在构造函数中张开赋值,实质上是对字段进行赋值,和天性的get/set访谈器未有关联。

6、分裂是怎么样?上面一贯重申自动属性,是因为电动属性和平时属性差异样,譬如只读普通属性(未有set访谈器)不能在构造函数中赋值。在未有自动属性以前,普通属性使用手续是率先声贝拉米(Bellamy)个字段如_id,然后声澳优(Ausnutria Hyproca)特本性Id,在get和set访问器中做一些操作,那些操作大多数是对字段_id的操作,可是有时和字段未有关系。普通属性能够像字段相近通过“.”的措施调用,但又像方法相近享有代码段(普通属性温昔不开发内部存款和储蓄器空间)。

但是C#3.0从此今后引进了自动属性,表明格局如public
int id { get; set; },C#6.0未来又有了public string FirstName { get;
set; } = “Jane”。自动属性分明开采了内部存款和储蓄器空间然后才有了自行属性的第一手赋值。其实在类中宣称自动属性会在编写翻译成IL中间语言中宣示贰个隐讳字段,然后生成隐敝字段的get/set方法,然后生成get/set访谈器。这里能够分解为什么只读普通属性不能在构造函数中赋值(和一贯赋值)而只读自动属性能够在构造函数中赋值(和直接赋值),因为无论直接赋值依然在构造函数中赋值,生成的IL代码中的构造函数中,操作的都以隐瞒字段,并从未访谈属性的set访谈器。(注意这里只是说的类中的自动属性,接口中也是能够有自动属性的,然而接口的活动属性并不会生成掩瞒字段只是概念get/set访谈器)

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