摘要:現在局域網已經普遍融入人們的生活，學校，企業都建立了自己的局域網，人們在局域網中的交流也是必不可少的，這時就需要一款安全可靠的局域網聊天軟件了，這也是做本設計的現實目的。

　　本設計是一個基于UDP的局域網聊天軟件,主要使用現在比較普遍和流行的C#語言，采用面向對象的方法，綜合運用數據庫編程技術、多線程開發技術、網絡通訊技術，以Microsoft Visual Studio 2008作為系統前臺應用程序開發工具，Microsoft SQL Server 2005作為后臺數據庫管理系統，在Windows XP平臺下進行開發。本設計的完成主要實現了以下功能：

　　1.實現了用戶注冊、登錄、聊天（加密）、服務器管理等功能

　　2.支持多用戶同時通信

　　3.支持點對點的文件傳輸，語音傳輸

    通過程序反復的測試和運行，本設計安全可靠，完成了本局域網聊天軟件的設計要求。

關鍵詞：局域網；聊天軟件；C#；UDP協議

Abstract:Now,the local area network has been widely integrated into people's lives,the schools,businesses have established their own local area network,the communication is essential for people,so it is necessary to have a secure chat software in lan,it is the objective for the design。

　　The topic of this paper is going to talk about that to design the chat software in lan based on udp. This local area network chat software using the design stream of the software project, using the C# language which is very common and popular, using the object-oriented approach, the technology of the database programming, multi-threading development technology and the network communication technology, makes Microsoft Visual Studio 2008 as the front application design tool, Microsoft SQL Server 2005 are used as the background DBMS( the database management system ), and it was programmed in the Windows XP System. The completion of the design to achieve the following main features：

　　1.Implemented user registration,login,chat(encryption),server management and other functions.

　　2.Communications from multiple users simutaneously.

　　3.Support point to point filetransfer,voice transmission.

    Through the process of repeated tseting and operation,the design is safety and reliable,completed the design requirements for the lan chat software.

Key Words: Local Area Network; Chat Software; C#; UDP protocol