Because the code of Android is managed code on dalvik virtual machine, it can be easily decompiled into code that we can recognize. I wrote an article before, decompiling the apk package of Android into smali file, and then recompiling the signature package to realize the function of tampering with apk. Recently, there is a new method to decompile the dex code of the classes.dex file in the Android apk package directly into java. Class binary code, and then from the. Class binary code to java source code. I don't need to say more. First of all, the tools we need are Dexjar and jd-gui. The first tool is Dexjar, which is used to convert the classex.dex file, that is, the dex binary code, into a standard. Java-like binary code, and then jd-gui decompiles the standard. Class binary code is converted into java source code. First, extract classes.dex from the apk package and put it in the dex2jar directory, and then execute dex2jar.bat classes.dex on the command line. At this point, after successful execution, a classes.dex.dex2jar.jar file will be generated and then opened with jd-gui. The figure below is similar to the source code of this program written by myself. This decompilation method is mainly used for your study and research. If you have any questions, you can discuss them with me by email. I hope you don't engage in malicious activities in this way. After all, it is not easy for others to work hard to write programs. In this way, we can roughly understand the logic and architecture of programs written by others. I hope it helps you. The experience of Android reverse apk program This paper mainly introduces how to reverse an Android APK application, and the methods provided in this paper are only for research and study. The tool needed in this paper is jdk, which is used to build the java runtime environment AxmlPrinter2.jar for reverse. The XML file baksmali.jar is used to reverse the classex.dex file. Because. The apk file of Android is actually a zip file, which can be opened directly with winrar.