apk反编译(6)用ProGuard 混淆、压缩代码，压缩资源。

1.android官方文档

　　https://developer.android.com/studio/build/shrink-code 主要内容如下：

1.1 压缩代码

混淆生成的文件：<module-name>/build/outputs/mapping/release/目录下
自定义要保留的代码,-keep与@keep
解码混淆，使用 <sdk-root>/tools/proguard/ 下的工具。
通过 Instant Run 启用代码压缩

1.2 压缩资源

shrinkResources
自定义要保留的资源
启用严格引用检查
移除未使用的备用资源
合并重复资源
排查资源压缩问题

1.3 官方proguard示例

　　Android SDK/tools/proguard/proguard-android.txt 是默认混淆文件,同目录下的proguard-android-optimize.txt 是优化版本。

　　在proguard/examples下有很多示例，如android.pro：

 #

 # This ProGuard configuration file illustrates how to process Android

 # applications.

 # Usage:

 #     java -jar proguard.jar @android.pro

 #

 # If you're using the Android SDK (version 2.3 or higher), the android tool

 # already creates a file like this in your project, called proguard.cfg.

 # It should contain the settings of this file, minus the input and output paths

 # (-injars, -outjars, -libraryjars, -printmapping, and -printseeds).

 # The generated Ant build file automatically sets these paths.

 # Specify the input jars, output jars, and library jars.

 # Note that ProGuard works with Java bytecode (.class),

 # before the dex compiler converts it into Dalvik code (.dex).

 # -injars  bin/classes

 # -injars  libs

 # -outjars bin/classes-processed.jar

 # -libraryjars /usr/local/android-sdk/platforms/android-9/android.jar

 #-libraryjars /usr/local/android-sdk/add-ons/google_apis-7_r01/libs/maps.jar

 # ...

 # Save the obfuscation mapping to a file, so you can de-obfuscate any stack

 # traces later on.

 -printmapping bin/classes-processed.map

 # You can print out the seeds that are matching the keep options below.

 #-printseeds bin/classes-processed.seeds

 # Preverification is irrelevant for the dex compiler and the Dalvik VM.

 -dontpreverify

 # Reduce the size of the output some more.

 -repackageclasses ''

 -allowaccessmodification

 # Switch off some optimizations that trip older versions of the Dalvik VM.

 -optimizations !code/simplification/arithmetic

 # Keep a fixed source file attribute and all line number tables to get line

 # numbers in the stack traces.

 # You can comment this out if you're not interested in stack traces.

 -renamesourcefileattribute SourceFile

 -keepattributes SourceFile,LineNumberTable

 # RemoteViews might need annotations.

 -keepattributes *Annotation*

 # Preserve all fundamental application classes.

 -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

 # Preserve all View implementations, their special context constructors, and

 # their setters.

 -keep public class * extends android.view.View {

     public <init>(android.content.Context);

     public <init>(android.content.Context, android.util.AttributeSet);

     public <init>(android.content.Context, android.util.AttributeSet, int);

     public void set*(...);

 }

 # Preserve all classes that have special context constructors, and the

 # constructors themselves.

 -keepclasseswithmembers class * {

     public <init>(android.content.Context, android.util.AttributeSet);

 }

 # Preserve all classes that have special context constructors, and the

 # constructors themselves.

 -keepclasseswithmembers class * {

     public <init>(android.content.Context, android.util.AttributeSet, int);

 }

 # Preserve the special fields of all Parcelable implementations.

 -keepclassmembers class * implements android.os.Parcelable {

     static android.os.Parcelable$Creator CREATOR;

 }

 # Preserve static fields of inner classes of R classes that might be accessed

 # through introspection.

 -keepclassmembers class **.R$* {

   public static <fields>;

 }

 # Preserve the required interface from the License Verification Library

 # (but don't nag the developer if the library is not used at all).

 -keep public interface com.android.vending.licensing.ILicensingService

 -dontnote com.android.vending.licensing.ILicensingService

 # The Android Compatibility library references some classes that may not be

 # present in all versions of the API, but we know that's ok.

 -dontwarn android.support.**

 # Preserve all native method names and the names of their classes.

 -keepclasseswithmembernames class * {

     native <methods>;

 }

 # Preserve the special static methods that are required in all enumeration

 # classes.

 -keepclassmembers class * extends java.lang.Enum {

     public static **[] values();

     public static ** valueOf(java.lang.String);

 }

 # Explicitly preserve all serialization members. The Serializable interface

 # is only a marker interface, so it wouldn't save them.

 # You can comment this out if your application doesn't use serialization.

 # If your code contains serializable classes that have to be backward

 # compatible, please refer to the manual.

 -keepclassmembers class * implements java.io.Serializable {

     static final long serialVersionUID;

     static final java.io.ObjectStreamField[] serialPersistentFields;

     private void writeObject(java.io.ObjectOutputStream);

     private void readObject(java.io.ObjectInputStream);

     java.lang.Object writeReplace();

     java.lang.Object readResolve();

 }

 # Your application may contain more items that need to be preserved;

 # typically classes that are dynamically created using Class.forName:

 # -keep public class mypackage.MyClass

 # -keep public interface mypackage.MyInterface

 # -keep public class * implements mypackage.MyInterface

2.proguard官方教程

　　https://www.guardsquare.com/en/products/proguard/manual 包含：

sdk/tools/proguard/bin/proguardgui.sh 界面工具教程
混淆选项列表
混淆示例
解混淆
Gradle plugin 配置教程
等等

　　sdk/tools/proguard/docs/index.html 是官方教程本地版本。

2.1 混淆选项列表

　　官方地址：https://www.guardsquare.com/en/products/proguard/manual/refcard

`@`filename	Short for '`-include` filename'.
`-include` filename	Read configuration options from the given file.
`-basedirectory` directoryname	Specifies the base directory for subsequent relative file names.
`-injars` class_path	Specifies the program jars (or apks, aabs, aars, wars, ears, jmods, zips, or directories).
`-outjars` class_path	Specifies the names of the output jars (or apks, aabs, aars, wars, ears, jmods, zips, or directories).
`-libraryjars` class_path	Specifies the library jars (or apks, aabs, aars, wars, ears, jmods, zips, or directories)
`-skipnonpubliclibraryclasses`	Ignore non-public library classes.
`-dontskipnonpubliclibraryclasses`	Don't ignore non-public library classes (the default).
`-dontskipnonpubliclibraryclassmembers`	Don't ignore package visible library class members.
`-keepdirectories` [directory_filter]	Keep the specified directories in the output jars (or wars, ears, zips, or directories).
`-target` version	Set the given version number in the processed classes.
`-forceprocessing`	Process the input, even if the output seems up to date.
`-keep` [,modifier,...] class_specification	Preserve the specified classes and class members.
`-keepclassmembers` [,modifier,...] class_specification	Preserve the specified class members, if their classes are preserved as well.
`-keepclasseswithmembers` [,modifier,...] class_specification	Preserve the specified classes and class members, if all of the specified class members are present.
`-keepnames` class_specification	Preserve the names of the specified classes and class members (if they aren't removed in the shrinking step).
`-keepclassmembernames`class_specification	Preserve the names of the specified class members (if they aren't removed in the shrinking step).
`-keepclasseswithmembernames`class_specification	Preserve the names of the specified classes and class members, if all of the specified class members are present (after the shrinking step).
`-if` class_specification	Specify classes and class members that must be present to activate the subsequent `keep` option.
`-printseeds` [filename]	List classes and class members matched by the various `-keep` options, to the standard output or to the given file.
`-dontshrink`	Don't shrink the input class files.
`-printusage` [filename]	List dead code of the input class files, to the standard output or to the given file.
`-whyareyoukeeping` class_specification	Print details on why the given classes and class members are being kept in the shrinking step.
`-dontoptimize`	Don't optimize the input class files.
`-optimizations` optimization_filter	The optimizations to be enabled and disabled.
`-optimizationpasses` n	The number of optimization passes to be performed.
`-assumenosideeffects` class_specification	Assume that the specified methods don't have any side effects, while optimizing.
`-assumenoexternalsideeffects`class_specification	Assume that the specified methods don't have any external side effects, while optimizing.
`-assumenoescapingparameters`class_specification	Assume that the specified methods don't let any reference parameters escape to the heap, while optimizing.
`-assumenoexternalreturnvalues`class_specification	Assume that the specified methods don't return any external reference values, while optimizing.
`-assumevalues` class_specification	Assume fixed values or ranges of values for primitive fields and methods, while optimizing.
`-allowaccessmodification`	Allow the access modifiers of classes and class members to be modified,while optimizing.
`-mergeinterfacesaggressively`	Allow any interfaces to be merged, while optimizing.
`-dontobfuscate`	Don't obfuscate the input class files.
`-printmapping` [filename]	Print the mapping from old names to new names for classes and class members that have been renamed, to the standard output or to the given file.
`-applymapping` filename	Reuse the given mapping, for incremental obfuscation.
`-obfuscationdictionary` filename 可自定义混淆字符	Use the words in the given text file as obfuscated field names and method names.
`-classobfuscationdictionary` filename	Use the words in the given text file as obfuscated class names.
`-packageobfuscationdictionary`filename	Use the words in the given text file as obfuscated package names.
`-overloadaggressively`	Apply aggressive overloading while obfuscating.
`-useuniqueclassmembernames`	Ensure uniform obfuscated class member names for subsequent incremental obfuscation.
`-dontusemixedcaseclassnames`	Don't generate mixed-case class names while obfuscating.
`-keeppackagenames` [package_filter]	Keep the specified package names from being obfuscated.
`-flattenpackagehierarchy`[package_name]	Repackage all packages that are renamed into the single given parent package.
`-repackageclasses` [package_name]	Repackage all class files that are renamed into the single given package.
`-keepattributes` [attribute_filter]	Preserve the given optional attributes; typically `可选的属性有：[` `Exceptions`,`InnerClasses`, `Signature`, `Deprecated`, `SourceFile`, `SourceDir`, `LineNumberTable`, `LocalVariableTable`, `LocalVariableTypeTable`, `Synthetic`, `EnclosingMethod`, `Annotation]`.
`-keepparameternames`	Keep the parameter names and types of methods that are kept.
`-renamesourcefileattribute` [string]	Put the given constant string in the `SourceFile`attributes.
`-adaptclassstrings` [class_filter]	Adapt string constants in the specified classes, based on the obfuscated names of any corresponding classes.
`-adaptresourcefilenames` [file_filter]	Rename the specified resource files, based on the obfuscated names of the corresponding class files.
`-adaptresourcefilecontents` [file_filter]	Update the contents of the specified resource files, based on the obfuscated names of the processed classes.
`-dontpreverify`	Don't preverify the processed class files.
`-microedition`	Target the processed class files at Java Micro Edition.
`-android`	Target the processed class files at Android.
`-verbose`	Write out some more information during processing.
`-dontnote` [class_filter]	Don't print notes about potential mistakes or omissions in the configuration.
`-dontwarn` [class_filter]	Don't warn about unresolved references at all.
`-ignorewarnings`	Print warnings about unresolved references, but continue processing anyhow.
`-printconfiguration` [filename]	Write out the entire configuration, in traditional ProGuard style, to the standard output or to the given file.
`-dump` [filename]	Write out the internal structure of the processed class files, to the standard output or to the given file.
`-addconfigurationdebugging`	Instrument the processed code with debugging statements that print out suggestions for missing ProGuard configuration.

2.2 混淆选项通配符

　　Keep 选项后面的匹配条件中，经常需要用到通配符，例如上面默认 proguard-android.txt 规则中的 void set*(***);。

　　常见的通配符如下：

通配符	描述
`<init>`	匹配所有构造函数
`<fields>`	匹配所有字段
`<methods>`	匹配所有方法，不包括构造函数
?	匹配任意单个字符
%	匹配任意原始数据类型，例如 boolean、int，但是不包括 void
*	匹配任意长度字符，但是不包括包名分隔符（ . )，例如 `android.support.*` 不匹配 android.support.annotation.Keep
**	匹配任意长度字符，包括包名分隔符（ . )，例如 `android.support.**` 匹配 support 包下的所有类
***	匹配任意类型，包括原始数据类型、数组
…	匹配任意数量的任意参数类型

2.3 解混淆

debug版本

　　　　如果有异常，直接点击行号就可以了。下图第25行。

release版本：

　　　　找到对应版本的mapping.txt以及对应的异常日志，如果没有日志可以从android studio logcat中复制，

　　　　1.打开ProGuard图形工具，选择左侧ReTrace 栏

　　　　2.在右侧Mapping file中找到对应的mapping.txt

　　　　3.把异常的堆栈信息复制到Obfuscated stack track中，或者点Load stack trace...按钮找到对应的文件。

　　　　4.点右下角ReTrace!按钮。

3.哪些不应该混淆

　　对于某些情况，ProGuard 会移除所有（并且只会移除）未使用的代码。不过，ProGuard 难以对许多情况进行正确分析，可能会移除应用真正需要的代码。

不该混淆	原因
当应用引用的类只来自 `AndroidManifest.xml` 文件时	混淆处理之后，类名就会被篡改，实际使用的类与 `manifest` 中注册的类并不匹配，出错。如android常用4组件和Application类
当应用调用的方法来自 Java 原生接口 (JNI) 时	混淆后，会找不对对应的方法的实现
当应用在运行时（例如使用反射或自检）操作代码时	混淆后，找不到相应的名字，经常发生 `NoSuchMethodException` 和 `NoSuchFiledException` 异常
序列化的类	经过混淆的"洗礼"之后，序列化之后的 `value` 对应的 `key` 已然变为没有意义的字段。同时，反序列化的过程创建对象从根本上来说还是借助于反射，混淆之后 `key`会被改变，所以也会违背我们预期的效果。
枚举	枚举类内部存在 `values` 方法，混淆后该方法会被重新命名，并抛出 `NoSuchMethodException`。 Android 系统默认的混淆规则文件中已经添加了对于枚举类的处理，无需再去做额外工作。
自定义控件不需要被混淆	view的一些回调方法会被修改，导致出错或者显示不正常。
JavaScript 调用 Java 的方法不应混淆	容易找不到方法
第三方库也不建议混淆	通常第3库以jar或者so方式存在，工具很难分析其中的调用关系。容易出错。
注解不能混淆	很多场景下注解被用作在运行时反射确定一些元素的特征，Android工程默认的混淆配置已经包含了保留注解的配置。

4.自定义混淆字典

4.1 以自定义混淆字典选项

-obfuscationdictionary filename 　　混淆属性名、方法名参考的字典
-classobfuscationdictionary filename 混淆类参考的字典
-packageobfuscationdictionary filename 混淆包名参考的字典

4.2 混淆字典规则

一行一个单词
空行、空格忽略，
标点符号无效
重复的字符被忽略　
# 后面的字符忽略
混淆属性和方法时，最好使用类对应的class文件中经存在的字符

4.3 android提供的字典示例

　　在sdk/tools/proguard/examples/dictionaries/ 目录下有字典示例：

4.4 使用混淆字典

　　可把一份字典示例文件（如 windows.txt）或者自定义一个字典文件复制到项目中，与proguard-rules.pro同级。

　　在proguard-rules.pro中添加混淆选项，然后开始生成apk。

 -obfuscationdictionary windows.txt

 -classobfuscationdictionary windows.txt

 -packageobfuscationdictionary windows.txt

　　如：

5.实例

5.1 自定义要保留的类或包

　　打完包后，用android studio分析下它。打开其中的dex文件，选择要保留的类，或者包 -> 右键 -> Generate Proguard keep rule

　　复制其中的内容到 proguard-rules.pro 下。

5.2 配置默认android混淆选项

　　把 sdk/tools/proguard/examples/android.pro 内容复制到 proguard-rules.pro中

　　把不必要的选项关掉。

5.3 打开混淆开关

　　在release配置里打开混淆开关

 1     ...

 2     buildTypes {

 3         release {

 4             minifyEnabled true

 5             shrinkResources true

 6             zipAlignEnabled = true

 7             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'

 8         }

 9         debug{

10             minifyEnabled false

11             shrinkResources false

12 //            useProguard false

13             zipAlignEnabled = true

14             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'

15         }

16     }

17     ...