Research And Realization On Reversing Techniques For Java

In view of the problems of software engineering development, such as, with the missing and default of some software source code and documents, it becomes more and more difficult for the development and maintenance, also for some legacy system program of understanding and reading. Reverse engineering technology becomes more and more important. Choosing the decompiler or abstract method on the premise to get the original system source code and structure information, which can save the cost of development, and improve the efficiency of the development.The design of previous tools is perfect, but still need to meet different needs according to different occasions in different groups. First of all, many decompiler tools are only for the source code from target executable file; UML class diagram modeling tools are only for objecting files to model, which don’t provide the source code. Secondly, the tools for the majority of new users are more complicated, many reverse tools require complex and special environment as a support, for the students or the new users who contact reverse technology rarely, to select a simple and easy to use is needed. In addition, with the increasingly sophisticated anti-reverse technology, we need methods to solve these, such as confusion, shelling technology. Therefore, a tool which can achieve these requirements and functions is suite our requirement, and it can decompile the file and also can abstract the structure information of the system program, then it not only can use legacy system to restore, but also meet demand of most users, which can realize the simple operation, and set the decompiler and UML class diagram modeling as a whole.The tool is to realize the reverse technology for the object oriented language named Java, which is divided into two functions:the first one is to realize the decompilation of Java class files, through the analysis of the class file structure, setting forth the process of decompilation, generating the system which has the Chinese man-machine interface for most users demand on the basis of the method, indicating the method of decipher obfuscated code, and add new function in the tool, which can realize to delete comments and notes, correspond the decompiled code and line number. The second is to abstract the information for the system after the source code, which is the UML class diagram. Through the analysis of lexical, syntactic and the extraction mechanism, and explain the abstract rules, finally can realize the UML model, which can reflect the overall structure of system program. Based on the two part functions, which is integrated the tool named as MyRec. and finally to prove the feasibility and validity of the reverse engineering tool.