Android 代码混淆proguard技术介绍

由于各种反编译工具的泛滥，作为Android程序员在2.3版本以前只能通过手动添加proguard来实现代码混淆

proguard这个工具是一个java代码混淆的工具

在2.3版本的sdk中 我们可以看到在android-sdk-windows/tools/下面多了一个proguard文件夹
google已经把proguard技术放在了android sdk里面 可以通过正常的编译方式也能实现代码混淆了
[img]http://dl2.iteye.com/upload/attachment/0091/0331/0d3bd7d7-cab5-30c4-b902-0daad7a5eb9d.gif[/img]
可以看见新建一个工程里面有default.properties和proguard.cfg

默认的default.properties代码如下

# This file is automatically generated by Android Tools.  
# Do not modify this file -- YOUR CHANGES WILL BE ERASED!  
#  
# This file must be checked in Version Control Systems.  
#  
# To customize properties used by the Ant build system use,  
# "build.properties", and override values to adapt the script to your  
# project structure.  
# Project target.  
target=android-9

我们可以看到proguard.cfg已经帮我们写好了优化代码脚本

-optimizationpasses 5
-dontusemixedcaseclassnames
-dontskipnonpubliclibraryclasses
-dontpreverify
-verbose
-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*
-keep public class * extends android.app.Activity
-keep public class * extends android.app.Application
-keep public class * extends android.app.Service
-keep public class * extends android.content.BroadcastReceiver
-keep public class * extends android.content.ContentProvider
-keep public class com.android.vending.licensing.ILicensingService
-keepclasseswithmembernames class * {
    native <methods>;
}
-keepclasseswithmembernames class * {
    public <init>(android.content.Context, android.util.AttributeSet);
}
-keepclasseswithmembernames class * {
    public <init>(android.content.Context, android.util.AttributeSet, int);
}
-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}
-keep class * implements android.os.Parcelable {
  public static final android.os.Parcelable$Creator *;
}

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。)

接下来 按照google帮助文档里说的

[quote]To enable ProGuard so that it runs as part of an Ant or Eclipse build, set the proguard.config property in the <project_root>/default.properties file. The path can be an absolute path or a path relative to the project's root.[/quote]

所以我们修改default.properties file

加上一句

proguard.config=proguard.cfg

如下

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

然后正常的编译签名即可

然后用Android Tools生成一个发布的apk即可

[img]http://dl2.iteye.com/upload/attachment/0091/0333/3eb8d8f9-507c-343a-9994-579bc337b4bb.gif[/img]

然后用反编译工具查看dex文件

最后导出反编译之后的混淆代码如下图

[img]http://dl2.iteye.com/upload/attachment/0091/0335/c09065b0-39b7-3d4b-8bbd-fa688379ce3a.gif[/img]

是不是很轻松加愉快!希望各位程序员都能保护好自己的Android代码!