Design And Implement Of Semi-Custom Batch VAT Invoicing System On C# And GoF Design Pattern

With the development of enterprises,the VAT invoice is also increasing.However,against the background of increasing labor cost,the increase of the invoice volume can not be completely solved by only relying on the new VAT invoice staff.Moreover,it is easy to make a mistake and low efficiency on fill in the VAT invoice by manual.Therefore in the increasing VAT invoice,it is of great practical significance to study the realization of rapid and accurate batch VAT invoicing through computer software system.The batch VAT invoicing system by converting the source data into the SAT's(The State Administration of Taxation)invoice standard file and import this file through SAT's interface to SAT's invoicing software for batch invoicing.A well-designed system of batch VAT invoicing is not only batch realize batch invoicing,compatible with multiple customers and various different source data formats,but also have short delivery time and low R&D cost.However,most of the current batch VAT invoicing system are customized by the ERP system developers,it requires to be familiar with SAT's standard that resulting in slower delivery time,high cost,and does not support various customers.In view of the above questions,this dissertation mainly studies using the GoF design pattern to improve code reuse and implement a batch VAT invoicing system for various customers,The main work and innovations of the dissertation is as follows:1)Proposing a "semi-customized" batch VAT invoice solution,which can share the common function modules,and customize the customer's individual needs to reduce the system cost.2)Using GoF factory design pattern to support enterprises' various source data and less code line.An enterprise customer only a implementation class,less than 500 code lines be completed.3)When dealing with abnormal invoice data,this dissertation apply the GoF Decorate Pattern to realize flexible calling of non-mandatory abnormal invoice data processing.4)In response to the differences type of SAT's invoice file standard,this dissertation apply the GoF template method pattern,summarize the generic step for SAT's invoice file standard,and override the special requirements for each type file which can improve code reuse.5)Opening invoicing and invoice processing APIs by "plugins" to extend the system function for enterprise's developer.Finally,the system is implemented by C# language,and tested and applied in 10 Foshan enterprise customers.The result shows that the system functions to meet customer demands,accurately,greatly improve the VAT invoicing efficiency.