The Design And Implementation Of The Android-based Instant Messaging System

With the rapid development of computer technology,IM(Instant Messaging)software has become the essential software on the phone,such as QQ,WeChat,etc.The rapid development and the large area coverage of the wireless local area network offer the opportunities to achieve the audio and video calls on the phone.Under the conditions,the IM's features are particularly prominent which is convenient,quick and stylish,and IM has become a mainstream moment of communication.Android,a mobile operating system based on the Linux,has been widely used because of its open source and easily development,so IM software has a good application prospect based on Android.The method and process of the IM system based on Android are studied in this paper.It briefly introduces the basis of relevant knowledge of the stream media real-time transfer protocol and the audio video coding standard,etc.The IM system which is based on Android mainly achieves online users obtain,instant messages(including chat,group chat,multiplayer chat and file transfer),the mechanism of session management,audio and video calls,etc.The software designs the network communications protocol based on UDP,realizes the data communication for every client in local area network that is fast and accurate.At the same time,the system designs the simple mechanism including reply messages,the retransmission of data package and slide window to make sure of credibility in transport.In order to ensure the quality and efficiency in file transfer,the system adds the function of breakpoint continuingly.In the mechanism of session management,it lays the foundation for realizing the three party services by the rational control of the call status of every client in the process of audio and video calls.During the development process,the system adopts multi-thread technology to receive and dispatch data,uses the class and interface files from the Libstreaming library to finish the encoding and build the session of audio and video.It is convenient and fast for people to chat,file transfer,group chat,multiplayer chat and audio & video calls in the same wireless local area network through this instant messaging software.At the same time,it works well with a good user experience,and has a certain use value.