泛型反射常见应用，通过类型创建实例，通过反射实现增删改查

Posted 2021-03-18 davidhuatit

public class Test
    {


        public void MyObj<T>() where T : class
        {
            //T t = new T();
            T t =System.Activator.CreateInstance<T>();
            //获取类型跟字段然后拿到对应名字方法跟字段就可以了
        }
    }

　　

微信官方创建实体的方法,通过泛型类型创建实例
System.Activator.CreateInstance<T>();





新增：

public static void Add<T>(T model)
        {
            Type t = typeof(T);
            string TableName = GetTableName(t);
            PropertyInfo[] pps = t.GetProperties();
            StringBuilder sb = new StringBuilder("insert into"+ TableName + "(");
            StringBuilder sbColumns = new StringBuilder();
            StringBuilder sbValues = new StringBuilder();
            foreach (PropertyInfo item in pps)
            {
                if (!IsNotMapper(item)&& !IsKey(item))
                {
                    sbColumns.Append(item.Name+",");
                    if (IsNoStr(item.PropertyType))
                    {
                        
                        if (item.GetValue(model)==null|| string.IsNullOrEmpty(item.GetValue(model).ToString()))
                        {
                            sbValues.Append("null,");
                        }
                        else
                        {
                            
                            if (IsBoolean(item.PropertyType))
                            {
                                bool bvalue = (bool)item.GetValue(model);
                                sbValues.Append((bvalue?1:0) + ",");
                            }
                            else
                            {
                                sbValues.Append(item.GetValue(model) + ",");
                            }
                            
                        }
                    }
                    else
                    {
                        sbValues.Append("‘"+item.GetValue(model) + "‘,");
                    }
                    
                }
            }
            string sql = string.Format("insert into " + TableName + "({0}) values({1})",sbColumns.ToString().TrimEnd(‘,‘), sbValues.ToString().TrimEnd(‘,‘));
            connection.Execute(sql);
        }

　　

修改：

public static void Update<T>(T model)
        {
            Type t = typeof(T);
            string TableName = GetTableName(t);
            PropertyInfo[] pps = t.GetProperties();
            StringBuilder sb = new StringBuilder();
            string where = "";
            foreach (PropertyInfo item in pps)
            {
                if (!IsNotMapper(item))
                {
                    string column = item.Name;
                    string value = item.GetValue(model).ToString();
                    if (!IsKey(item))
                    {
                        if (IsNoStr(item.PropertyType))
                        {
                            if (IsBoolean(item.PropertyType))
                            {
                                bool bvalue = (bool)item.GetValue(model);
                                value = bvalue ? "1" : "0";
                            }
                            sb.Append(column + "=" + value + ",");
                        }
                        else
                        {
                            sb.Append(column + "=‘" + value + "‘,");
                        }
                    }
                    else
                    {
                        where = column + "=" + value;
                    }
                }
            }

            string sql = string.Format("update {0} set {1} where {2} ",TableName,sb.ToString().TrimEnd(‘,‘),where);
        }

　　

 

 

 

删除：

public static void Delete<Key, T>(Key id)
        {
            Type tp = typeof(T);
            PropertyInfo[] pps = tp.GetProperties();
            string KeyName = "";
            Key Value = id;
            foreach (PropertyInfo item in pps)
            {
                if (!IsNotMapper(item)&& IsKey(item))
                {
                    KeyName = item.Name;
                }
            }
            if (IsNoStr(typeof(Key)))
            {
                string sql = "delete " + GetTableName(tp) + " where " + KeyName + "=" + Value;
            }
            else
            {
                string sql = "delete " + GetTableName(tp) + " where " + KeyName + "=‘" + Value + "‘";
            }
        }

　　

 

判断字段或类是否包含特性：

/// <summary>
        /// 是否包含该特性
        /// </summary>
        /// <param name="item"></param>
        /// <param name="tp"></param>
        /// <returns></returns>
        private static bool IsAttribute(PropertyInfo item, Type tp)
        {
            var attr = item.GetCustomAttributes(tp, true);
            if (attr.Length <= 0)
                return false;
            return true;
        }

　　

 

 

抓取指定特性值（如表名，子段说明等特殊的属性）：

/// <summary>
        /// 查询表名
        /// </summary>
        /// <param name="t"></param>
        /// <returns></returns>
        private static string GetTableName(Type t)
        {
            string Name = t.Name;
            object[] os = t.GetCustomAttributes(typeof(TablNameAttribute), true);
            if (os.Length > 0)
            {
                TablNameAttribute ta = os[0] as TablNameAttribute;
                Name = ta.TableName;
            }
            return Name;
        }

　　

 

泛型反射是我们在做系统架构时需要经常用到的，如果能熟练应用到项目中可以对业务开发起到约束和管控的作用。