一、前言

为何需要混淆呢？简单的说，就是将原本正常的项目文件，对其类，方法，字段，重新命名,a,b,c,d,e,f…之类的字母，达到混淆代码的目的，这样反编译出来，结构乱糟糟的，看了也头大。

另外说明一下，本文的混淆总结基于Android Studio的IDE开发环境。

二、官方默认的混淆配置

其实在android Studio中做混淆，基本就是对Proguard-rules.pro文件的操作。混淆的过程也是有规律可循的。先看看官方的proguard-android.txt文件，位于/tools/proguard目录下，不知道怎么写，可以当成模板，复制一份出来到自己的工程，改成自己项目所需的混淆配置。内容如下：

# This is a configuration file for ProGuard.# http://proguard.sourceforge.net/index.html#manual/usage.html-dontusemixedcaseclassnames-dontskipnonpubliclibraryclasses-verbose# Optimization is turned off by default. Dex does not like code run# through the ProGuard optimize and preverify steps (and performs some# of these optimizations on its own).-dontoptimize-dontpreverify# Note that if you want to enable optimization, you cannot just# include optimization flags in your own project configuration file;# instead you will need to point to the# "proguard-android-optimize.txt" file instead of this one from your# project.properties file.-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 * {    native 
     
      ;}# 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 {   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 {   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);}-keepclassmembers class * implements android.os.Parcelable {  public static final android.os.Parcelable$Creator CREATOR;}-keepclassmembers class **.R$* {    public static 
      
       ;}# 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.**# Understand the @Keep support annotation.-keep class android.support.annotation.Keep-keep @android.support.annotation.Keep class * {*;}-keepclasseswithmembers class * {    @android.support.annotation.Keep 
       
        ;}-keepclasseswithmembers class * {    @android.support.annotation.Keep 
        
         ;}-keepclasseswithmembers class * {    @android.support.annotation.Keep 
         
          (...);}
         
        
       
      
     

这个混淆默认采取一些通用的规则，view，activity，Parcelable，注解，R文件，枚举这类的东西都不会混淆，我们也不能混淆这些，否则release版本会报错。

三、Android Studio开启混淆配置

很简单，只要设置minifyEnabled为true即可。

buildTypes {        release {            minifyEnabled true//true开启混淆配置，false关闭            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'            signingConfig signingConfigs.duqian_android_keystore        }       debug{//省略}}

四、Android混淆的通用规则

1. 系统混淆配置

-dontusemixedcaseclassnames          #混淆时不使用大小写混合类名-dontskipnonpubliclibraryclasses     #不跳过library中的非public的类-verbose                             #打印混淆的详细信息-dontoptimize                        #不进行优化，建议使用此选项，-dontpreverify                       #不进行预校验,Android不需要,可加快混淆速度。-ignorewarnings                      #忽略警告#-optimizationpasses 5               #指定代码的压缩级别

2. 常用的一些混淆配置

-keepattributes Signature #范型#native方法不混淆-keepclasseswithmembernames class * {    native 
     
      ;}#v4包不混淆-keep class android.support.v4.app.** { *; }-keep interface android.support.v4.app.** { *; }#Gson混淆配置-keep class sun.misc.Unsafe { *; }-keep class com.idea.fifaalarmclock.entity.***-keep class com.google.gson.** { *; }#JavaBean-keepclassmembers public class cn.net.duqian.bean.** {   void set*(***);   *** get*();}-keep class com.xx.duqian_cloud.JavaScriptInterface { *; }#webview js#忽略 libiary 混淆-keep class io.vov.vitamio.** { *; }#butterknife不混淆-keep class butterknife.** { *; }-dontwarn butterknife.internal.**-keep class **$$ViewBinder { *; }-keepclasseswithmembernames class * {    @butterknife.* 
      
       ;}-keepclasseswithmembernames class * {    @butterknife.* 
       
        ;}
       
      
     

3. 第三方框架一般不混淆（但也要看具体情况）

-keepclassmembers class * {   public 
     
       (org.json.JSONObject);}#okhttp-dontwarn okhttp3.**-keep class okhttp3.**{*;}-keep interface okhttp3.**{*;}#okio-dontwarn okio.**-keep class okio.**{*;}-keep interface okio.**{*;}-dontwarn retrofit2.**-keep class retrofit2.** { *; }-keepattributes Signature-keepattributes Exceptions-dontwarn rx.**-keep class rx.**{*;}
     

四、Android混淆的方法和通配符对照表

五、不能混淆的情况总结

• Java的反射，为什么不能混淆呢？因为代码混淆，类名、方法名、属性名都改变了，而反射它还是按照原来的名字去反射，结果只射出一个程序崩溃
• 注解用了反射，所以不能混淆。 不混淆任何包含native方法的类的类名以及native方法名，否则找不到本地方法。
• Activity不能混淆，因为AndroidManifest.xml文件中是完整的名字
• 自定义view也是带了包名写在xml布局中，不能混淆

六、混淆后使用时常见问题

当项目中出现so的native代码找不到Java的方法的时候，可以尝试将

-keepclasseswithmembernames class * {    native 
     
      ;}
     

更改为：

-keep class * {    native 
     
      ;}