好处：
1 防止反编译
2 可以压缩代码大小
如果需要对项目进行全局混码，只需要进行一步操作：
将project.properties的中
“# proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt”的“#”去掉就可以
project.properties
# This file is automatically generated by Android Tools.
# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
#
# This file must be checked in Version Control Systems.
#
# To customize properties used by the Ant build system edit
# "ant.properties", and override values to adapt the script to your
# project structure.
#
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
# Project target.
target=android-19
如果有一些代码不能被混淆，比如需要加入了so文件，需要调用里面的方法，
那么调用JNI访问so文件的方法就不能被混码。在导出的时候，可能不会报错。
但是在手机上运行的时候，需要调用so文件的时候，就会报某某方法无法找到。
这个时候就需要用到proguard-project.txt。
在老版本中，创建项目的时候，会给出proguard.cfg，但是在的新版中创建项目则不会有任何提示。
这个时候需要只要将proguard.cfg的内容加入到proguard-project.txt中，
再根据自己的需要进行编辑即可。
proguard-project.txt
# 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 ${sdk.dir}/tools/proguard/proguard-android.txt
# You can edit the include path and order by changing the ProGuard
# include property in project.properties.
#
# For more details, see
# http://developer.android.com/guide/developing/tools/proguard.html
# Add any project specific keep options here:
-optimizationpasses 5
-dontusemixedcaseclassnames
-dontskipnonpubliclibraryclasses
-dontpreverify
-verbose
-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*
-keep public class * extends android.app.Activity
-keep public class * extends android.app.Application
-keep public class * extends android.app.Service
-keep public class * extends android.content.BroadcastReceiver
-keep public class * extends android.content.ContentProvider
-keep public class * extends android.app.backup.BackupAgentHelper
-keep public class * extends android.preference.Preference
-keep public class com.android.vending.licensing.ILicensingService
-keepclasseswithmembernames class * {
native <methods>;
}
-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet);
}
-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet, int);
}
-keepclassmembers class * extends android.app.Activity {
public void *(android.view.View);
}
-keepclassmembers enum * {
public static **[] values();
public static ** valueOf(java.lang.String);
}
-keep class * implements android.os.Parcelable {
public static final android.os.Parcelable$Creator *;
}
-keep class MD5
# 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 *;
#}
/**
配置解释
*/
-optimizationpasses 5 压缩的级别
-dontusemixedcaseclassnames Ab Fe A a adb adc 不使用大小写混合
-dontskipnonpubliclibraryclasses 三方.jar
-dontpreverify 要不要使用预校验
-verbose 在混淆的时候是否记录日志
-optimizations !code/simplification/arithmetic,!field/*,!class/merging/* 压缩的算法
保持那些类不被混淆 四大组件都不能被混淆
-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 * extends android.app.backup.BackupAgentHelper
-keep public class * extends android.preference.Preference
-keep public class com.android.vending.licensing.ILicensingService
-keepclasseswithmembernames class * {
native <methods>; jni java nativew interface
}
自定义控件也不能被混淆
-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet);
}
-keepclasseswithmembers class * {
public <init>(android.content.Context, android.util.AttributeSet, int);
}
-keepclassmembers class * extends android.app.Activity {
public void *(android.view.View);
}
枚举
-keepclassmembers enum * {
public static **[] values();
public static ** valueOf(java.lang.String);
}
-keep class * implements android.os.Parcelable {
public static final android.os.Parcelable$Creator *;
}
-keep class MD5