Android studio利用gradle打jar包并混淆的方法详解

本文主要介绍了android studio利用gradle打jar包并混淆的方法，下面话不多说，来看看详细的介绍吧。

首先打jar包的配置很简单，使用jar的task，可以参考gradle官方文档，具体代码如下：

task buildjar(type: jar, dependson: ['assemblerelease']) {
 destinationdir = file('build/outputs/jar/')
 appendix = ""
 basename = ""
 version = sdk_version
 // manifest信息
 def map = ['version': sdk_version,
  'gradle': project.gradle.gradleversion,
  'vendor': '',
  'date': new date().getdatetimestring()
 ]
 manifest.attributes(map)
 from('build/intermediates/classes/release/')
 exclude('**/buildconfig.class')
 exclude('**/buildconfig\$*.class')
 exclude('**/r.class')
 exclude('**/r\$*.class')
 include('**/*.class')
}

但是发现上面打出来的jar包中的代码没有被混淆，于是加混淆。使用混淆的proguard.gradle.proguardtask task时，发现总是报如下错误：

java.io.ioexception: the output jar [....jar] must be specified after an input jar, or it will be empty.

按照上面的提示，outjars是写在injars后面啊，it will be empty是提示哪里有问题？以为是proguard-rules.pro文件中的配置有问题，结果把文件清空，还是报上面的错误，错误原因不得而知了。在这个问题上耗了很长时间，最终还是没有解决。
突然看到上面的assemblerelease task想起了平常打apk时，会使用到这个task，打出来的apk会自动混淆。

那这个assemblerelease task就会依赖处理混淆的task，于是查看了输出日志：

to honour the jvm settings for this build a new jvm will be forked. please consider using the daemon: https://docs.gradle.org/2.14.1/userguide/gradle_daemon.html.
observed package id 'system-images;android-22;google_apis;x86' in inconsistent location 'android-sdk-windows-studio\system-images\addon-google_apis-google-22
\x86' (expected 'android-sdk-windows-studio\system-images\android-22\google_apis\x86')
observed package id 'system-images;android-22;google_apis;x86' in inconsistent location 'android-sdk-windows-studio\system-images\addon-google_apis-google-22
\x86' (expected 'android-sdk-windows-studio\system-images\android-22\google_apis\x86')
incremental java compilation is an incubating feature.  
:sdk:prebuild up-to-date                  
:sdk:extractproguardfiles
:sdk:prereleasebuild
:sdk:checkreleasemanifest
:sdk:predebugandroidtestbuild up-to-date
:sdk:predebugbuild up-to-date
:sdk:predebugunittestbuild up-to-date
:sdk:prereleaseunittestbuild up-to-date
:sdk:preparecomandroidsupportanimatedvectordrawable2510library up-to-date 
:sdk:preparecomandroidsupportappcompatv72510library up-to-date 
:sdk:preparecomandroidsupportsupportcompat2510library up-to-date
:sdk:preparecomandroidsupportsupportcoreui2510library up-to-date
:sdk:preparecomandroidsupportsupportcoreutils2510library up-to-date
:sdk:preparecomandroidsupportsupportfragment2510library up-to-date 
:sdk:preparecomandroidsupportsupportmediacompat2510library up-to-date 
:sdk:preparecomandroidsupportsupportv42510library up-to-date
:sdk:preparecomandroidsupportsupportvectordrawable2510library up-to-date
:sdk:preparereleasedependencies
:sdk:compilereleaseaidl up-to-date 
:sdk:compilereleasendk up-to-date
:sdk:compilelint up-to-date
:sdk:copyreleaselint up-to-date
:sdk:compilereleaserenderscript up-to-date
:sdk:generatereleasebuildconfig   
:sdk:generatereleaseresvalues up-to-date
:sdk:generatereleaseresources up-to-date
:sdk:mergereleaseresources up-to-date 
:sdk:processreleasemanifest up-to-date
:sdk:processreleaseresources up-to-date 
:sdk:generatereleasesources
:sdk:incrementalreleasejavacompilationsafeguard   
:sdk:compilereleasejavawithjavac   
:sdk:compilereleasejavawithjavac - is not incremental (e.g. outputs have changed, no previous execution, etc.).
注: 某些输入文件使用或覆盖了已过时的 api。                
注: 有关详细信息, 请使用 -xlint:deprecation 重新编译。               
:sdk:extractreleaseannotations   
:sdk:mergereleaseshaders up-to-date 
:sdk:compilereleaseshaders up-to-date
:sdk:generatereleaseassets up-to-date
:sdk:mergereleaseassets up-to-date
:sdk:mergereleaseproguardfiles up-to-date
:sdk:packagereleaserenderscript up-to-date
:sdk:packagereleaseresources up-to-date 
:sdk:processreleasejavares up-to-date
:sdk:transformresourceswithmergejavaresforrelease up-to-date
:sdk:transformclassesandresourceswithproguardforrelease   
proguard, version 5.2.1
reading input...       
reading program directory [sdk\build\intermediates\classes\release] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-media-compat\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-compat\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-fragment\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-core-ui\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\animated-vector-drawable\25.1.0\jars\classes.jar] (filte
red)
reading library jar [android-sdk-windows-studio\extras\android\m2repository\com\android\support\support-annotations\25.1.0\support-annotations-25.1.0.jar] (f
iltered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-v4\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-vector-drawable\25.1.0\jars\classes.jar] (filter
ed)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\appcompat-v7\25.1.0\jars\classes.jar] (filtered)
reading library jar [sdk\build\intermediates\exploded-aar\com.android.support\support-core-utils\25.1.0\jars\classes.jar] (filtered)
reading library jar [\android-sdk-windows-studio\platforms\android-25\android.jar]
reading library jar [\android-sdk-windows-studio\platforms\android-25\optional\org.apache.http.legacy.jar]
note: duplicate definition of library class [android.net.http.httpresponsecache]
note: duplicate definition of library class [android.net.http.sslcertificate$dname]
note: duplicate definition of library class [android.net.http.sslerror]
note: duplicate definition of library class [android.net.http.sslcertificate]
note: duplicate definition of library class [org.apache.http.params.coreconnectionpnames]
note: duplicate definition of library class [org.apache.http.params.httpconnectionparams]
note: duplicate definition of library class [org.apache.http.params.httpparams]
note: duplicate definition of library class [org.apache.http.conn.scheme.socketfactory]
note: duplicate definition of library class [org.apache.http.conn.scheme.layeredsocketfactory]
note: duplicate definition of library class [org.apache.http.conn.scheme.hostnameresolver]
note: duplicate definition of library class [org.apache.http.conn.connecttimeoutexception]
note: there were 11 duplicate class definitions.
 (http://proguard.sourceforge.net/manual/troubleshooting.html#duplicateclass)
initializing...
note: you're ignoring all warnings!     
ignoring unused library classes...     
 original number of library classes: 5857
 final number of library classes: 383
printing kept classes, fields, and methods...
shrinking...
printing usage to [sdk\build\outputs\mapping\release\usage.txt]...
removing unused program classes and class elements...   
 original number of program classes: 52    
 final number of program classes: 48
obfuscating...
printing mapping to [sdk\build\outputs\mapping\release\mapping.txt]...
writing output...
preparing output jar [sdk\build\intermediates\transforms\proguard\release\jars\3\3\main.jar]
 copying resources from program directory [sdk\build\intermediates\classes\release] (filtered)
printing classes to [sdk\build\outputs\mapping\release\dump.txt]...
:sdk:transformclassesandresourceswithsynclibjarsforrelease   
:sdk:mergereleasejnilibfolders up-to-date
:sdk:transformnative_libswithmergejnilibsforrelease up-to-date 
:sdk:transformnative_libswithsyncjnilibsforrelease up-to-date
:sdk:bundlerelease   
:sdk:compilereleasesources
:sdk:assemblerelease
:sdk:buildjar   
  
build successful.

好家伙，被我发现了。其中从:sdk:transformclassesandresourceswithproguardforrelease这个task就可以看到，下面一堆日志是关于proguard混淆工具的，最后可以看到：

preparing output jar [sdk\build\intermediates\transforms\proguard\release\jars\3\3\main.jar]

这个main.jar就是混淆后的jar包，只不过这个jar还包含了r类和buildconfig类的信息，所以将这个信息过滤掉就可以。但问题也来了，jar包都已经打好了，怎么配置混淆？解决方法是只要把jar包当输入就行了，最终配置如下：

task buildjar(type: jar, dependson: ['assemblerelease']) {
 destinationdir = file('build/outputs/jar/')
 appendix = "" // sdk的后缀名称
 basename = "" // sdk名称
 version = sdk_version // 这个常量是在gradle.properties中配置的
 // manifest信息
 def map = ['version': sdk_version,
  'gradle': project.gradle.gradleversion,
  'vendor': '',
  'date': new date().getdatetimestring()
 ]
 manifest.attributes(map)
 from(project.ziptree('build/intermediates/transforms/proguard/release/jars/3/3/main.jar'))
 exclude('**/buildconfig.class')
 exclude('**/buildconfig\$*.class')
 exclude('**/r.class')
 exclude('**/r\$*.class')
 include('**/*.class')
}

总结

ok，任务搞定。以上就是这篇文章的全部内容了，希望本文的内容对各位android开发者们能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对的支持。