Activator.CreateInstance 方法 (Type)和Class1 obj=new Class1()方法实例化

需要动态的创建一个实例模型的时候，就用Activator.CreateInstance(Type type);

如果是明确的知道要创建哪个实例的模型，就可以用 new Class1()了。

也可以通过程序集Assembly.CreateInstance()来创建，不过其实程序集创建也是调用的Activator.CreateInstance(Type type)。

public static object GetFromDataTable(DataTable dt, Type objectType, int row)
        {
            if (dt == null)
            {
                return null;
            }
            if (dt.Rows.Count <= row)
            {
                return null;
            }

            object obj = Activator.CreateInstance(objectType);

            PropertyInfo[] props = objectType.GetProperties(BindingFlags.Public | BindingFlags.Instance);

            foreach (DataColumn dc in dt.Columns)
            {
                foreach (PropertyInfo p in props)
                {
                    if (p.Name.Equals(dc.ColumnName, StringComparison.OrdinalIgnoreCase))
                    {
                        if (!dt.Rows[row].IsNull(dc.ColumnName))
                        {
                            object destObj = dt.Rows[row][dc.ColumnName];

                            bool succ = false;

                            if (p.PropertyType == destObj.GetType())
                            {
                                succ = true;
                            }
                            else
                            {
                                if (p.PropertyType == typeof(int))
                                {
                                    succ = true;
                                    int tmpInt = 0;
                                    int.TryParse(destObj.ToString(), out tmpInt);
                                    destObj = tmpInt;
                                }
                                else if (p.PropertyType == typeof(long))
                                {
                                    succ = true;
                                    long tmpLong = 0;
                                    long.TryParse(destObj.ToString(), out tmpLong);
                                    destObj = tmpLong;
                                }
                                else if (p.PropertyType == typeof(bool))
                                {
                                    succ = true;
                                    bool tmpBool = false;
                                    bool.TryParse(destObj.ToString(), out tmpBool);
                                    destObj = tmpBool;
                                }
                                else if (p.PropertyType == typeof(DateTime))
                                {
                                    succ = true;
                                    DateTime tmpDateTime;
                                    DateTime.TryParse(destObj.ToString(), out tmpDateTime);
                                    destObj = tmpDateTime;
                                }
                                else if (p.PropertyType == typeof(float))
                                {
                                    succ = true;
                                    float tmpFloat;
                                    float.TryParse(destObj.ToString(), out tmpFloat);
                                    destObj = tmpFloat;
                                }
                                else if (p.PropertyType == typeof(decimal))
                                {
                                    succ = true;
                                    decimal tmpDecimal;
                                    decimal.TryParse(destObj.ToString(), out tmpDecimal);
                                    destObj = tmpDecimal;
                                }
                                else if (p.PropertyType == typeof(double))
                                {
                                    succ = true;
                                    double tmpDouble;
                                    double.TryParse(destObj.ToString(), out tmpDouble);
                                    destObj = tmpDouble;
                                }
                                else if (p.PropertyType == typeof(char))
                                {
                                    succ = true;
                                    char tmpChar;
                                    char.TryParse(destObj.ToString(), out tmpChar);
                                    destObj = tmpChar;
                                }
                                else if (p.PropertyType == typeof(Int16))
                                {
                                    succ = true;
                                    Int16 tmpInt16;
                                    Int16.TryParse(destObj.ToString(), out tmpInt16);
                                    destObj = tmpInt16;
                                }
                                else
                                {
                                    succ = false;
                                }
                            }
                            if(succ)
                            {
                                p.SetValue(obj, destObj, null);
                            }
                        }
                    }
                }
            }

            return obj;
        }