The Broken-point Continuingly Transferring And Multi-thread Download Component Based On HTTP/FTP Protocol

Human has entered the information age, the network communication is reflected in thevarious fields. The inevitable trend of the information age is how to make a full use ofnetwork bandwidth to get the fastest download speed, so as to reach the unity of time andspace and efficiency. Now the file transfer between people become more and more frequently,however, the file transfer may be interrupted by some accident, such as network interruptionor computer power failure. In order to respond to these emergencies, this article develop adownload software with the functions of broken-point continuingly transfer and multi-threaddownload, this download software can accelerate download speed, at the same time avoid thewaste of resources. In addition, the advantages of this software are fresh interface, occupysmall memory, quick start, detailed download information and set download parameters.The programming of this paper is based on VC++MFC framework, the software hasgood stability because of the MFC features of package and inherit, at the same time, the MFCpackage the CSocket class that related to network programming, so can use socket to program,and transport large quantities of dates. The socket programming is not only support transferprotocol, but also ensure the transmission is error-free and no repeat.This paper described the download process of client and server through the study ofmulti-thread technology, and realized the calls of multi-thread functions based on thedownload process. The Synchronous objects of thread class ensure the coordination betweeneach thread after threads are created, at the same time call the priority function, suspendfunction and resume function to complete the management between each thread. After eachthread download completed, then combine temporary files of each thread into a wholedownload file though the read and write operation.Finally, this paper tests the software functions, at the beginning tests the broken-pointcontinuingly transferring function in power-off and network interruption respectively, theresults verify this function has implemented. The test of the multi-thread function uses thecontrastive method, let the software work in single-thread and multi-thread respectively, theresult show the download speed in multi-thread is faster than single-thread. The implementation of the software draws a conclusion that multi-threadcommunications are useful in high efficiency fields. The multi-thread technology can be usedin the engineering control field, open one main thread to complete some initialization andcoordinate each auxiliary thread, then the auxiliary thread can complete some time-consumingtask in the background, so it can implement efficiently through the management of threadpriority.