【作者】 李浩；

【导师】 王建新；

【作者基本信息】 中南大学 ， 计算机科学与技术， 2012， 硕士

【摘要】 随着电子信息技术的飞速发展,文件重写技术在商业领域发挥了越来越大的作用,尤其是在SSL VPN网关使用以及软件复用过程中,文件重写技术都有关键应用。因此,针对应用广泛的文件类型,设计和实现一套高效稳定的文件重写系统具有重要意义。本文首先介绍了目前文件重写技术的研究现状,考虑到实际应用背景和理论研究意义,将PDF、Flash和Java Applet三类文件格式选定为重写对象,以超链接为重写目标,分析和研究了PDF、Flash和Java Applet三种文件类型的格式规范。在此基础上,对大量测试用例的字节码进行了分析,确定了三类文件的字节码中的超链接信息及特征。然后,对需求进行深入分析,设计出针对三类文件的文件重写系统。其次,逐步实现了文件重写系统中的文件解压/压缩模块、字节码解析模块、URL重写模块三个核心模块,其中涉及的关键技术包括字节码动态重写技术、字节码校验与纠正技术、反射重写技术、URL还原与属性赋值重写技术、Java Applet重新签名技术、Base64加密/解密和JNI技术等七项技术。在对文件重写系统功能测试的同时,使用性能监测工具TPTP对文件重写系统进行了性能瓶颈分析,根据分析结果优化性能,并对最终的系统进行重写速度测试,结果显示文件重写系统在功能和性能上都达到了实际应用的需求。最后,对本文的研究工作进行了简要总结,并对今后的研究进行了展望。更多还原

【Abstract】 With the increasing development of electronic and information technology, rewriting techniques are becoming increasingly important whether to the significance of software modification and reuse or to the role of commercial fields. Consequently, it is valuable to design and implement some effective rewriting systems for widespread rewriting files.Firstly, this paper introduced the research status of file rewriting technology. According to significance of application and theory, this paper choose three file types as the object of rewriting and the target of hyperlink, such as PDF, Flash and Java applet, which are widely used in web service rewriting. On that basis, after analyzing a large number of byte code of test cases and confirming the hyperlink information and characteristics of three file types in the byte code, this paper respectively designed the three file-rewriting systems for the above three file types in demand. Secondly, this paper gradually completed the three core modules of web service rewriting, for example the file decompression/compression module, byte code parsing module and the URL rewriting module. There were many important technologies for this implementation, such as byte code dynamic rewriting technology, byte code verification and correction techniques, reflection rewriting technology, URL restore and rewriting technology of property assignment, java applets automatic signature technology, Base64encryption/decryption and JNI technology. Thirdly, this paper made a bottleneck analysis with the method of TPTP, then tested the functionality and velocity. The test results showed that it fulfilled requirement. Finally, this paper summarized the current existing issues and provided some more directions.更多还原