在Android4.0之前的版本建的工程中有一个proguard.cfg文件，混淆时直接将混淆代码加进去，然后在 project.properties这个文件底下加入proguard.config=proguard.cfg这句话就可以了；
在4.0版本建的工程中发现proguard.cfg没了，多了proguard-project.txt这个文件。反正我没管，直接将 proguard.cfg这个文件拷过去用了，没发现什么问题，下面是混淆时proguard.cfg 中的代码：
-optimizationpasses 5
-dontusemixedcaseclassnames
-dontskipnonpubliclibraryclasses
-dontpreverify
-verbose
-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*
-keepattributes *Annotation*
-keepattributes JavascriptInterface
-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 *;
}
//这些需要说明，这是工程中引入的第三方的类库，不需要我们做混淆，因为人家已经做过混淆处理了 ，-keep关键字修饰的一些都是不需要混淆处理的
-libraryjarslibs/android-support-v4.jar
-libraryjarslibs/commons-io-1.3.2.jar
-libraryjarslibs/library.jar
-libraryjarslibs/pushservice-2.4.0.jar
-libraryjarslibs/nineoldandroids-2.4.0.jar
## commons-io-1.3.2.jar
-keep public class org.apache.commons.** {*;}
## support-v4
-dontwarn android.support.v4.**
-keep class android.support.v4.** { *; }
-keep interface android.support.v4.app.** { *; }
-keep public class * extends android.support.v4.**
-keep public class * extends android.app.Fragment
## annotations.jar
-keep public class android.annotation {*;}
## pushservice-2.4.0.jar
-keep public class android.content.pm {*;}
-keep public class android.baidu.** {*;}
## nineoldandroids-2.4.0.jar
-keep public class com.nineoldandroids.** {*;}
## library.jar
-keep public class com.nostra13.universalimageloader.** {*;}
## kxml2-min-2.3.0.jar
-keep public class org.** {*;}
最后别忘了将proguard.config=proguard.cfg这句话加入到project.properties这个文件下面
