android怎么代码混淆

从SDK2.3开始我们可以看到在android-sdk-windows\tools\下面多了一个proguard文件夹proguard是一个java代码混淆的工具，通过proguard，别人即使反编译你的apk包，也只会看到一些让人很难看懂的代码，从而达到保护代码的作用。

来看看android-sdk-windows\tools\lib\proguard.cfg的内容：

Java代码??

1. -optimizationpasses?5??
2. -dontusemixedcaseclassnames??
3. -dontskipnonpubliclibraryclasses??
4. -dontpreverify??
5. -verbose??
6. -optimizations?!code/simplification/arithmetic,!field/*,!class/merging/*??
7. ??
8. -keep?public?class?*?extends?android.app.Activity??
9. -keep?public?class?*?extends?android.app.Application??
10. -keep?public?class?*?extends?android.app.Service??
11. -keep?public?class?*?extends?android.content.BroadcastReceiver??
12. -keep?public?class?*?extends?android.content.ContentProvider??
13. -keep?public?class?*?extends?android.app.backup.BackupAgentHelper??
14. -keep?public?class?*?extends?android.preference.Preference??
15. -keep?public?class?com.android.vending.licensing.ILicensingService??
16. ??
17. -keepclasseswithmembernames?class?*?{??
18. ????native?<methods>;??
19. }??
20. ??
21. -keepclasseswithmembernames?class?*?{??
22. ????public?<init>(android.content.Context,?android.util.AttributeSet);??
23. }??
24. ??
25. -keepclasseswithmembernames?class?*?{??
26. ????public?<init>(android.content.Context,?android.util.AttributeSet,?int);??
27. }??
28. ??
29. -keepclassmembers?enum?*?{??
30. ????public?static?**[]?values();??
31. ????public?static?**?valueOf(java.lang.String);??
32. }??
33. ??
34. -keep?class?*?implements?android.os.Parcelable?{??
35. ??public?static?final?android.os.Parcelable$Creator?*;??
36. }??

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从脚本中可以看到，混淆中保留了继承自Activity、Service、Application、BroadcastReceiver、ContentProvider等基本组件以及com.android.vending.licensing.ILicensingService，

并保留了所有的Native变量名及类名，所有类中部分以设定了固定参数格式的构造函数，枚举等等。(详细信息请参考<proguard_path>/examples中的例子及注释。)

让proguard.cfg起作用的做法很简单，就是在eclipse自动生成的default.properties文件中加上一句“proguard.config=proguard.cfg”就可以了

完整的default.properties文件应该如下：

?

Java代码??

1. #?This?file?is?automatically?generated?by?Android?Tools.??
2. #?Do?not?modify?this?file?--?YOUR?CHANGES?WILL?BE?ERASED!??
3. #??
4. #?This?file?must?be?checked?in?Version?Control?Systems.??
5. #??
6. #?To?customize?properties?used?by?the?Ant?build?system?use,??
7. #?"build.properties",?and?override?values?to?adapt?the?script?to?your??
8. #?project?structure.??
9. ??
10. #?Project?target.??
11. target=android-9??
12. proguard.config=proguard.cfg??

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大功告成，正常的编译签名后就可以防止代码被反编译了。反编译经过代码混淆的apk得到的代码应该类似于下面的效果，是很难看懂的：

?如果您使用的是2.3之前的SDK版本也没关系，把上面的proguard.cfg文件复制一份放到项目中，然后进行相同的操作即可