/// <summary>
/// 将ExcelDataRow快速转换为指定类型
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dataRow"></param>
/// <returns></returns>
public static T FastConvert <T>(ExcelDataRow dataRow)
{
//利用表达式树，动态生成委托并缓存，得到接近于硬编码的性能
//最终生成的代码近似于(假设T为Person类)
//Func<ExcelDataRow,Person>
// new Person(){
// Name = Convert(ChangeType(dataRow.DataCols.SingleOrDefault(c=>c.PropertyName == prop.Name).ColValue,prop.PropertyType),prop.ProertyType),
// Age = Convert(ChangeType(dataRow.DataCols.SingleOrDefault(c=>c.PropertyName == prop.Name).ColValue,prop.PropertyType),prop.ProertyType)
// }
// }
string propertyNames = string.Empty;
dataRow.DataCols.ForEach(c => propertyNames += c.PropertyName + "_");
var key = typeof(T).FullName + "_" + propertyNames.Trim('_');
if (!Table.ContainsKey(key))
{
List <MemberBinding> memberBindingList = new List <MemberBinding>();
MethodInfo singleOrDefaultMethod = typeof(Enumerable)
.GetMethods()
.Single(m => m.Name == "SingleOrDefault" && m.GetParameters().Count() == 2)
.MakeGenericMethod(new[] { typeof(ExcelDataCol) });
foreach (var prop in typeof(T).GetProperties())
{
Expression <Func <ExcelDataCol, bool> > lambdaExpr = c => c.PropertyName == prop.Name;
MethodInfo changeTypeMethod = typeof(ExpressionMapper).GetMethods().Where(m => m.Name == "ChangeType").First();
Expression expr =
Expression.Convert(
Expression.Call(changeTypeMethod
, Expression.Property(
Expression.Call(
singleOrDefaultMethod
, Expression.Constant(dataRow.DataCols)
, lambdaExpr)
, typeof(ExcelDataCol), "ColValue"), Expression.Constant(prop.PropertyType))
, prop.PropertyType);
memberBindingList.Add(Expression.Bind(prop, expr));
}
MemberInitExpression memberInitExpression = Expression.MemberInit(Expression.New(typeof(T)), memberBindingList.ToArray());
Expression <Func <ExcelDataRow, T> > lambda = Expression.Lambda <Func <ExcelDataRow, T> >(memberInitExpression, new ParameterExpression[]
{
Expression.Parameter(typeof(ExcelDataRow), "p")
});
Func <ExcelDataRow, T> func = lambda.Compile();//拼装是一次性的
Table[key] = func;
}
var ss = (Func <ExcelDataRow, T>)Table[key];
return(((Func <ExcelDataRow, T>)Table[key]).Invoke(dataRow));
}
/// <summary>
/// 设置Excel行的校验结果
/// </summary>
/// <param name="row"></param>
/// <param name="isValid"></param>
/// <param name="col"></param>
/// <param name="errorMsg"></param>
public static void SetNotValid(this ExcelDataRow row, bool isValid, ExcelDataCol dataCol, string errorMsg)
{
if (!isValid)
{
row.IsValid = false;
row.ErrorMsg += dataCol.ColName + errorMsg + ";";
}
}
/// 直接反射
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="row"></param>
/// <returns></returns>
//public static T Convert<T>(this ExcelDataRow row)
//{
// return Convert<T>(row, GetValue);
//}
/// <summary>
/// 将ExcelDataRow转换为指定类型
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="row"></param>
/// <returns></returns>
private static T Convert <T>(this ExcelDataRow row, Func <ExcelDataRow, Type, string, object> func)
{
Type t = typeof(T);
object o = Activator.CreateInstance(t);
t.GetProperties().ToList().ForEach(p =>
{
if (p.IsDefined(typeof(ColNameAttribute)))
{
p.SetValue(o, func(row, p.PropertyType, p.GetCustomAttribute <ColNameAttribute>().ColName));
}
});
return((T)o);
}
/// <summary>
/// 利用反射将ExcelDataRow转换为制定类型，性能较差
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="row"></param>
/// <returns></returns>
//public static T ConvertByRefelection<T>(this ExcelDataRow row)
//{
// Type t = typeof(T);
// object o = Activator.CreateInstance(t);
// t.GetProperties().ToList().ForEach(p => {
// if (p.IsDefined(typeof(ColNameAttribute)))
// {
// ExcelDataCol col = row.DataCols.SingleOrDefault(c => c.ColName == p.GetCustomAttribute<ColNameAttribute>().ColName);
// if (col != null)
// {
// p.SetValue(o, ExpressionMapper.ChangeType(col.ColValue, p.PropertyType));
// }
// }
// });
// return (T)o;
//}
/// <summary>
/// 利用表达式树，将ExcelDataRow快速转换为指定类型
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="row"></param>
/// <returns></returns>
public static T FastConvert <T>(this ExcelDataRow row)
{
return(ExpressionMapper.FastConvert <T>(row));
}
