Android 混淆机制
一、为什么要加入混淆机制？
为了防止apk被反编译后，很容易被其他人看懂。
混淆机制的本质是什么？
把原来有具体含义的类名，变量名，方法名，修改成让人看不懂的名字，例如方法名getUserName编程了方法名a
二、如何混淆代码
Android工程目录下有两个文件，project.properties，proguard-project.txt
1、project.properties（工程目录下）内容如下：
# 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 edit
# "ant.properties", and override values to adapt the script to your
# project structure.
#
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
# proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
# Project target.
target=android-18
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
也就是说，如果你要混淆和压缩代码，那么就取消下面一行的注释。
proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
此行指定了混淆代码的配置文件，是/home/jltxgcy/android-sdk-linux/tools/proguard/proguard-android.txt。如果想优化你的代码，配置文件换成/home/jltxgcy/android-sdk-linux/tools/proguard/proguard-android-optimize.txt。
冒号后面就是自定义混淆规则文件，如下：
2、proguard-project.txt（工程目录下）
# To enable ProGuard in your project, edit project.properties
# to define the proguard.config property as described in that file.
#
# Add project specific ProGuard rules here.
# By default, the flags in this file are appended to flags specified
# in ${sdk.dir}/tools/proguard/proguard-android.txt
# You can edit the include path and order by changing the ProGuard
# include property in project.properties.
#
# For more details, see
# http://developer.android.com/guide/developing/tools/proguard.html
# Add any project specific keep options here:
# If your project uses WebView with JS, uncomment the following
# and specify the fully qualified class name to the JavaScript interface
# class:
#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
# public *;
#}
# Add project specific ProGuard rules here.
# By default, the flags in this file are appended to flags specified
# in ${sdk.dir}/tools/proguard/proguard-android.txt 增加自定义混淆机制，默认情况下，这里的规则会被附加到
/home/jltxgcy/android-sdk-linux/tools/proguard/proguard-android.txt后面。
3、导出混淆后的apk
默认的debug版本的apk是不包含混淆信息的，所以要产生release版本的apk，点击右键，选择Android Tools->Export Signed Application Package，此时导出的apk是包含混淆信息的。
三、实例分析
1、project.properties如下：
# This file is automatically generated by Android Tools.
# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
#
# This file must be checked in Version Control Systems.
#
# To customize properties used by the Ant build system edit
# "ant.properties", and override values to adapt the script to your
# project structure.
#
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
proguard.config=${sdk.dir}/tools/proguard/proguard-android-optimize.txt:proguard-project.txt
# Project target.
target=android-18
2、 proguard-project.txt如下：
# To enable ProGuard in your project, edit project.properties
# to define the proguard.config property as described in that file.
#
# Add project specific ProGuard rules here.
# By default, the flags in this file are appended to flags specified
# in ${sdk.dir}/tools/proguard/proguard-android.txt
# You can edit the include path and order by changing the ProGuard
# include property in project.properties.
#
# For more details, see
# http://developer.android.com/guide/developing/tools/proguard.html
# Add any project specific keep options here:
# If your project uses WebView with JS, uncomment the following
# and specify the fully qualified class name to the JavaScript interface
# class:
#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
# public *;
#}
-keep public class * extends android.app.Activity #保留继承Activity类的类名
-keep public class * extends android.app.Application #保留继承Application类的类名
#-keepclassmembers class com.jltxgcy.crack.MainActivity$SNChecker {
# public boolean isRegistered();
#}
-keep class android.support.v4.** { *; }//保留这个第三方jar包不被混淆
-keep interface android.support.v4.** { *; }
3、/home/jltxgcy/android-sdk-linux/tools/proguard/proguard-android-optimize.txt如下：
# This is a configuration file for ProGuard.
# http://proguard.sourceforge.net/index.html#manual/usage.html
# Optimizations: If you don't want to optimize, use the
# proguard-android.txt configuration file instead of this one, which
# turns off the optimization flags. Adding optimization introduces
# certain risks, since for example not all optimizations performed by
# ProGuard works on all versions of Dalvik. The following flags turn
# off various optimizations known to have issues, but the list may not
# be complete or up to date. (The "arithmetic" optimization can be
# used if you are only targeting Android 2.0 or later.) Make sure you
# test thoroughly if you go this route.
-optimizations !code/simplification/arithmetic,!code/simplification/cast,!field/*,!class/merging/*
-optimizationpasses 5
-allowaccessmodification
-dontpreverify
# The remainder of this file is identical to the non-optimized version
# of the Proguard configuration file (except that the other file has
# flags to turn off optimization).
-dontusemixedcaseclassnames
-dontskipnonpubliclibraryclasses
-verbose
-keepattributes *Annotation*
-keep public class com.google.vending.licensing.ILicensingService
-keep public class com.android.vending.licensing.ILicensingService
# For native methods, see http://proguard.sourceforge.net/manual/examples.html#native
-keepclasseswithmembernames class * { #保留native的方法的方法名和包含native方法的类的类名不变
native <methods>;
}
# keep setters in Views so that animations can still work.
# see http://proguard.sourceforge.net/manual/examples.html#beans
-keepclassmembers public class * extends android.view.View {#保留继承于View的类中set*和get*方法的方法名不变
void set*(***);
*** get*();
}
# We want to keep methods in Activity that could be used in the XML attribute onClick
-keepclassmembers class * extends android.app.Activity { #保留继承于Activity的类中以View为参数，返回值是void的方法的方法名
public void *(android.view.View);
}
# For enumeration classes, see http://proguard.sourceforge.net/manual/examples.html#enumerations
-keepclassmembers enum * {
public static **[] values();
public static ** valueOf(java.lang.String);
}
-keep class * implements android.os.Parcelable { #保留实现了Parcelable接口的类的类名以及Parcelable$Createor内部类的类名
public static final android.os.Parcelable$Creator *;
}
-keepclassmembers class **.R$* { #保留R$*类中静态字段的字段名
public static <fields>;
}
# The support library contains references to newer platform versions.
# Don't warn about those in case this app is linking against an older
# platform version. We know about them, and they are safe.
-dontwarn android.support.**
4、导出签名的apk，命名为CrackApk01.apk。
5、在proguard-project.txt中去掉注释
-keepclassmembers class com.jltxgcy.crack.MainActivity$SNChecker {
public boolean isRegistered();
} 再次导出签名的apk，命名为CrackApk02.apk。
四、proguard-android-optimize.txt和proguard-project.txt说明
-keep class 保留类名
-keepclassmembers 保留类中的方法或者字段名
-keepclasseswithmembernames 保留类名和类中的方法或者字段名
此部分详见：http://proguard.sourceforge.net/index.html#manual/examples.html
五、工程源码下载
http://download.csdn.net/detail/jltxgcy/7125411