JAVA高级面试进阶训练营视频教程

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升级版本：

NetCore sdk 2.2.108 、AspNetCore 2.2.0、EFCore 2.2.6

所有程序引用均从NuGet上下载，并支持NetCore 

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问题： 

问题1：No coercion operator is defined between types 'System.Int16' and 'System.Boolean'（mysql 数据库类型转化中int16 byte bool 转化问题）

解决方案：

引用 Pomelo.EntityFreamworkCore.Mysql 2.2.0 代替 MySql.Data.EntityFrameworkCore 

问题2：Error generated for warning 'Microsoft.EntityFrameworkCore.Database.Transaction.AmbientTransactionWarning: An ambient transaction has been detected. The current provider does not support ambient transactions.（环境事务、分布式事务问题）

解决方案：

因为Pomelo.EFCore.Mysql 2.2.0 不支持TransactionScope 

所以 采用 using (var scope = DataContextFactory.GetDataContext().Database.BeginTransaction(System.Data.IsolationLevel.RepeatableRead)) 或者 

using (var scope = new CommittableTransaction()) 这两种事务代替

问题3：HttpResponseMessage 问题

解决方案：

两个解决方案，建议第一个

1：改为File()返回   2：添加引用 并在startup里注册 services.AddMvc().AddWebApiConventions();

问题4：依赖问题

解决方案：采用Autofac4.9.3 版本支持NetCore 

问题5：模型转换 Model  不支持static 

解决方案：将之前的代码改为第二个里面的 ，并在调用的地方统一 实例化

        public center_flow CenterFlowDto_to_CenterFlow(CenterFlowDto dto)
        {
            var mapper = CreateMap<CenterFlowDto, center_flow>();

            return mapper.Map<CenterFlowDto, center_flow>(dto);
        }

/// <summary>
        /// 险别列表
        /// </summary>
        /// <param name="list"></param>
        /// <returns></returns>
        public List<compensate_insurance> CompensateInsuranceDtoList_to_EntityList(List<CompensateInsuranceDto> list)
        {
            //var mapper = CreateMap<CompensateAdjustmentDto, compensate_adjustment>();
            //return mapper.Map<List<CompensateInsuranceDto>, List<compensate_insurance>>(list);

            var config = new MapperConfiguration(cfg => { cfg.CreateMap<List<CompensateInsuranceDto>, List<compensate_insurance>>(); });
            var mapper = config.CreateMapper();

            return mapper.Map<List<CompensateInsuranceDto>, List<compensate_insurance>>(list);
        }

 

 

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帮助类：SqlQuery<T>

  1 public static class DataContextExtend
  2     {
  3         public static List<T> SqlQuery<T>(this DatabaseFacade facade, string sql, params object[] parameters)
  4         {
  5             using (var conn = new MySqlConnection(facade.GetDbConnection().ConnectionString))
  6             {
  7                 conn.Open();
  8                 var ds = new DataSet();
  9                 using (var da = new MySqlDataAdapter(sql, conn.ConnectionString))
 10                 {
 11                     if (parameters.Any())
 12                     {
 13                         da.SelectCommand.Parameters.AddRange(parameters);
 14                     }
 15                     da.Fill(ds);
 16                 }
 17 
 18                 conn.Close();
 19                 if (ds.Tables.Count > 0)
 20                 {
 21                     return ToDataList<T>(ds.Tables[0]);
 22                 }
 23                 else
 24                 {
 25                     return new List<T>();
 26                 }
 27             }
 28         }
 29         /// <summary>
 30         /// 返回首行首列
 31         /// </summary>
 32         /// <typeparam name="T"></typeparam>
 33         /// <param name="facade"></param>
 34         /// <param name="sql"></param>
 35         /// <param name="parameters"></param>
 36         /// <returns></returns>
 37         public static T SqlCount<T>(this DatabaseFacade facade, string sql, params object[] parameters)
 38         {
 39             using (var conn = new MySqlConnection(facade.GetDbConnection().ConnectionString))
 40             {
 41                 conn.Open();
 42                 T result;
 43                 var ds = new DataSet();
 44 
 45                 using (var commend = new MySqlCommand(sql, conn))
 46                 {
 47                     if (parameters.Any())
 48                         commend.Parameters.AddRange(parameters);
 49                     result = (T)commend.ExecuteScalar();
 50                 }
 51 
 52                 conn.Close();
 53 
 54                 return result;
 55 
 56             }
 57 
 58         }
 59 
 60 
 61         /// <summary>
 62         /// DataTable转成List
 63         /// </summary>
 64         /// <typeparam name="T"></typeparam>
 65         /// <param name="dt"></param>
 66         /// <returns></returns>
 67         public static List<T> ToDataList<T>(this DataTable dt)
 68         {
 69             var list = new List<T>();
 70             var plist = new List<PropertyInfo>(typeof(T).GetProperties());
 71             if (typeof(T) == typeof(string))
 72             {
 73                 foreach (DataRow givenObject in dt.Rows)
 74                 {
 75                     for (int i = 0; i < dt.Columns.Count; i++)
 76                     {
 77                         if (givenObject != DBNull.Value && givenObject != null)
 78                         {
 79                             var instance = givenObject.ToString();  // Your custom conversion to string.
 80                             list.Add((T)(object)instance);
 81                         }
 82                         else
 83                         {
 84                             list.Add((T)(object)null);
 85                         }
 86                     }
 87                 }
 88             }
 89             else if (typeof(T).IsClass)
 90             {
 91                 foreach (DataRow item in dt.Rows)
 92                 {
 93                     T s = Activator.CreateInstance<T>();
 94                     for (int i = 0; i < dt.Columns.Count; i++)
 95                     {
 96                         PropertyInfo info = plist.Find(p => p.Name.ToUpper() == dt.Columns.ColumnName.ToUpper());
 97                         if (info != null)
 98                         {
 99                             try
100                             {
101                                 if (!Convert.IsDBNull(item))
102                                 {
103                                     object v = null;
104                                     if (info.PropertyType.ToString().Contains("System.Nullable"))
105                                     {
106                                         v = Convert.ChangeType(item, Nullable.GetUnderlyingType(info.PropertyType));
107                                     }
108                                     else
109                                     {
110                                         if (info.PropertyType.BaseType != null && info.PropertyType.BaseType.ToString().Contains("System.Enum"))
111                                         {
112                                             //将字符串转换为枚举对象
113                                             //v = Enum.Parse(info.PropertyType, item.ToString());
114                                             v = int.Parse(item.ToString());
115                                         }
116                                         else
117                                         {
118                                             v = Convert.ChangeType(item, info.PropertyType);
119                                         }
120                                     }
121                                     info.SetValue(s, v, null);
122                                 }
123                             }
124                             catch (Exception ex)
125                             {
126                                 throw new Exception("字段[" + info.Name + "]转换出错," + ex.Message);
127                             }
128                         }
129                     }
130                     list.Add(s);
131                 }
132             }
133             else if (typeof(T).BaseType == typeof(System.ValueType))
134             {
135                 try
136                 {
137                     foreach (DataRow item in dt.Rows)
138                     {
139                         for (int i = 0; i < dt.Columns.Count; i++)
140                         {
141                             if (item != DBNull.Value && item != null)
142                             {
143                                 if (plist.Count > 0)
144                                 {
145                                     list.Add((T)((object)Convert.ChangeType(item, plist.LastOrDefault()?.PropertyType)));
146                                 }
147                                 else
148                                 {
149                                     if (item.GetType().ToString() == "System.Int64" && typeof(T).FullName == "System.Int32")
150                                     {
151                                         list.Add((T)((object)int.Parse(item.ToString())));
152                                     }
153                                     else
154                                     {
155                                         list.Add((T)((object)item));
156                                     }
157                                 }
158                             }
159                             else
160                             {
161                                 list.Add((T)(object)null);
162                             }
163                         }
164                     }
165                 }
166                 catch (Exception ex)
167                 {
168                     throw new Exception("类型[" + typeof(T) + "]转换出错," + ex.Message);
169                 }
170             }
171             return list;
172         }
173 
174     }

 

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