Java卡字节码优化方法与研究实践.pdf

华中科技大学硕士学位论文 Java卡字节码优化方法的研究与实践姓名:韩晶申请学位级别:硕士专业:工业工程指导教师:向文 20080529 I 摘要 Java 卡是一种基于 Java 语言的智能卡。 Java 智能卡现已被广泛运用于银行、社会保障等安全性要求很高的领域中。因为智能卡空间和处理器速度的约束,一个应用程序在 Java 卡上运行时,面临的最大问题是存储空间的不足和对程序执行时间的严格限制。因此,对下载到卡中的字节码进行优化是十分必要的。本文在分析了现有方法的特点和不足的基础上, 提出了一种综合使用扩展指令集和分段压缩算法的 Java 卡字节码混合优化方法。本文研究的主要内容是 Java 卡字节码文件的结构特点及其优化方法。首先通过对 Java 卡虚拟机和 Java 卡字节码文件结构的分析, 参考已有的 Java 字节码文件优化方法, 给出一种混合模式的压缩优化算法。通过对字节码文件的优化,得到占用空间较少、且没有降低执行速率的字节码文件。然后通过对应用在 Java 智能卡上运行过程的分析和 Java 卡硬件,设计了一种有效且可行的卡上字节码解压缩方案。最后,详细给出了基于卡外压缩和卡上解压的 Java 卡字节码优化器实现方案,包括开发环境的搭建及 Java 卡虚拟机的改写、卡上及卡下优化器的实现。文章的结尾处,我们通过效率分析和实践给出了结果和讨论,提出了一些改进校验效率的建议和展望。关键词: Java 智能卡字节码优化字节码压缩优化方法 II Abstract As a new kind of smart card based on Java la nguage, Java card is widely used in the highly security fields such as bank, social security etc. An applet executing on a Java card, faces scarce memory resources and fixed executi on time constraints. For this reason, it is extrodinary essential to optimize the cap files which are loaded to the Java card. This paper attempts to design and implement a Java car d bytecode optimizator synthetical used redefining instructions and Basic-p ression based on the anal ysis characteristics and disadvantages of the existing methods. The research key point of this paper is th e structure of the bytecode file and the optimized method. Firstly, we consult the exis ting Java byte code optimization from the analysis of the Java card virtual machine and Java card byte code files construction, and put forward a hybrid pression algorithm optimization based on hybrid model. Then through the optimization we can obtain the byt ecode files which have smaller size with a minimal execution time penalty. Then we analyze the process of the applications running on the Java card and the hardware resources on car d; design a feasible and effective on-card pression algorithm. At last, the details scheme of Java card Optimizator based on off-pression and on-card pression including constructing