.Net 用反射实现字符串的格式化输出

Public Function FormatColData(ByVal Source As String, ByVal DataType As String, ByVal DataFormat As String) As String Dim rflag As Boolean = False Dim tflag As Boolean = False Try Dim tt As System.Type = System.Type.GetType(DataType) Dim m As Object = Activator.CreateInstance(tt) Dim myparse As System.Reflection.MethodInfo Dim mytostring As System.Reflection.MethodInfo Dim myMethods() As Object = tt.GetMethods For xx As Integer = 0 To myMethods.Length - 1 If myMethods(xx).Name.ToLower = "parse" And myMethods(xx).GetParameters.Length = 1 Then '查找参数数目为1，且为String型的那个Parse方法 If System.Type.GetTypeCode(myMethods(xx).GetParameters(0).ParameterType) = System.TypeCode.String Then myparse = myMethods(xx) rflag = True End If End If If myMethods(xx).name.tolower = "tostring" And myMethods(xx).getparameters.length = 1 Then '查找参数数目为1，且为String型的那个ToString方法 If System.Type.GetTypeCode(myMethods(xx).GetParameters(0).ParameterType) = System.TypeCode.String Then mytostring = myMethods(xx) tflag = True End If End If If rflag And tflag Then Exit For Next If rflag And tflag Then '查找到对应的方法，则调用该方法返回结果 Dim params(myparse.GetParameters().Length - 1) As Object, params1(mytostring.GetParameters().Length - 1) As Object params(0) = Source params1(0) = DataFormat m = myparse.Invoke(m, params) Return mytostring.Invoke(m, params1) Else '否则直接返回原始数据 Return Source End If Catch ex As Exception '出错，直接返回原始数据 Return Source End Try End Function

 

FormatColData("2010/01/01","System.DateTime","yyyy-MM-dd HH:mm:ss")     返回："2010-01-01 00:00:00"

FormatColData("12345.6","System.Double","￥#,#0.00")    返回："￥12,345.60"

FormatColData("12","System.Int32","00000#")    返回："000012"

 

原理是通过DataType参数找到对应的对象，然后通过Parse方法将Source字符串转成对应的对象，再通过ToString转回指定格式的字符串。

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