Android 应用插件

Jacqueline季 · 发表于 2021-1-26 16:21

最近为了解一个盒子上app在我们平台上无法工作的问题，去浅尝了反编译apk并在smali中注入代码，推荐一个叫Android Killer的IDE工具，几乎集成了所有反编译和打包的功能。同时也了解该app使用的插件加载，之所以会使用到插件来完成该功能，因为该app涉及到底层的audio实现，audio在framework会在各家平台有不同定制，利用插件就能保证对主程序来说平台都一样，而插件就根据各个平台的不同去做不同实现。
下面简要介绍一下该app的插件实现方法：
1、插件也是以apk的形式存在的
先来看看插件的Manifest
<?xml version=&#34;1.0&#34; encoding=&#34;utf-8&#34;?>
<manifest android:versionCode=&#34;1&#34; android:versionName=&#34;1.0&#34; package=&#34;com.kelvinwu.earlycmccplugin&#34; platformBuildVersionCode=&#34;19&#34; platformBuildVersionName=&#34;4.4.2-1456859&#34;
  xmlns:android=&#34;http://schemas.android.com/apk/res/android&#34;>
<application>
      <meta-data android:name=&#34;IPlugin&#34; android:value=&#34;com.kelvinwu.cmccplugin.EarlyAppEvent&#34; />
      <meta-data android:name=&#34;IMicrophone&#34; android:value=&#34;com.kelvinwu.cmccplugin.MicrophoneController&#34; />
      <meta-data android:name=&#34;IKaraoke&#34; android:value=&#34;com.kelvinwu.cmccplugin.EarlyISingEvent&#34; />
      <meta-data android:name=&#34;IAudioTrack&#34; android:value=&#34;com.kelvinwu.cmccplugin.AudioTracker&#34; />
      <meta-data android:name=&#34;IAudioTrackProfile&#34; android:value=&#34;com.kelvinwu.cmccplugin.AudioTrackProfile&#34; />
      <meta-data android:name=&#34;HardWareLevel&#34; android:value=&#34;2&#34; />
      <meta-data android:name=&#34;Manufacturer&#34; android:value=&#34;kelvinwu&#34; />
      <service android:name=&#34;com.kelvinwu.cmccplugin.PluginService&#34;>
         <intent-filter>
            <action android:name=&#34;com.cmcc.karaoke.plugin&#34; />
         </intent-filter>
      </service>
</application>
</manifest>
可以看到application下有两类tag：meta-data和service
meta-data：标签中name是接口的名字，value是实现该接口的具体实现类的名字，主程序中可以根据需要实现的接口去拿实现类的对象。
service：定义了一个有很特殊的名字的action，这个的作用是针对已经安装好的插件，主app能够通过pm去查询这样的一个service，用于辨别哪些package是插件。
这里的插件有两种存在方式：1、被安装（通过特殊的service去查询即可） 2、未安装（apk包中asset自带）
app会优先去查找系统中已经安装过的，如果找不到会用apk包中带的插件包。
2、如何使用插件中的类
app中提供了一个插件工具类，主要功能就是根据我们需要的接口类，根据插件创建出具体的实现类。
InterfaceClass I = function(InterfaceClass.class);
对外就这样封装使用很简单方便，下面看看代码实现，因为是反编译的就不是很好看，基本原理很简单。
final class d
  implements b
{
  private static final String b = MainApplication.b().getApplicationInfo().dataDir;
  private static final String c = b + &#34;/plugin/asset.apk&#34;;
  private static final String d = b + &#34;/plugin/asset.cfg&#34;;
  private static final String e = b + &#34;/plugin/libs&#34;;
  private static final String f = b + &#34;/plugin/opt&#34;;
  HashMap<String, ClassLoader> a = new HashMap();
  private ApplicationInfo g = null;

/*
返回一个可用的插件的application
*/
  private ApplicationInfo a()
  {
Object localObject2;
StringBuilder localStringBuilder;
if (this.g == null)
{
//优先查找已经安装的package
   localObject1 = new ArrayList();
   localObject2 = com.iflytek.app.b.b().getPackageManager().queryIntentServices(new Intent(&#34;com.cmcc.karaoke.plugin&#34;), 128).iterator();
   while (((Iterator)localObject2).hasNext()) {
      ((ArrayList)localObject1).add(((ResolveInfo)((Iterator)localObject2).next()).serviceInfo.applicationInfo);
   }
//从已经安装的package中找到第一个能满足需求的package的applicationinfo
   this.g = a((List)localObject1);
   localObject2 = com.iflytek.log.b.a(this);
   localStringBuilder = new StringBuilder(&#34;verify installed packages pass = &#34;);
   if (this.g == null)
   {
      localObject1 = &#34;null&#34;;
      ((com.iflytek.log.b)localObject2).c((String)localObject1);
   }
}
else if (this.g == null)
{
//其次查找asset中自带的插件
   this.g = b();
   localObject2 = com.iflytek.log.b.a(this);
   localStringBuilder = new StringBuilder(&#34;verify assets packages pass = &#34;);
   if (this.g != null) {
      break label233;
   }
}
label233:
for (Object localObject1 = &#34;null&#34;;; localObject1 = this.g.packageName)
{
   ((com.iflytek.log.b)localObject2).c((String)localObject1);
   if (this.g == null)
   {
      this.g = d(&#34;empty.apk&#34;);
      com.iflytek.log.b.a(this).c(&#34;use empty package = &#34; + this.g.packageName);
   }
   return this.g;
   localObject1 = this.g.packageName;
   break;
}
  }

/*
参数1：apk绝对路径
参数2：native lib库路径
*/
  private static ApplicationInfo a(String paramString1, String paramString2)
  {
PackageInfo localPackageInfo = MainApplication.b().getPackageManager().getPackageArchiveInfo(paramString1, 128);
if (localPackageInfo != null)
{
   localPackageInfo.applicationInfo.sourceDir = paramString1;
   localPackageInfo.applicationInfo.nativeLibraryDir = paramString2;
   return localPackageInfo.applicationInfo;
}
return null;
  }

/*
选出符合要求的application
*/
  private ApplicationInfo a(List<ApplicationInfo> paramList)
  {
paramList = paramList.iterator();
while (paramList.hasNext())
{
   ApplicationInfo localApplicationInfo = (ApplicationInfo)paramList.next();
   if (a(localApplicationInfo)) {
      return localApplicationInfo;
   }
}
return null;
  }

  private Object a(ApplicationInfo paramApplicationInfo, String paramString)
  {
try
{
   String str1 = paramApplicationInfo.packageName;
   String str2 = paramApplicationInfo.sourceDir;
   String str3 = paramApplicationInfo.nativeLibraryDir;
   ClassLoader localClassLoader = (ClassLoader)this.a.get(str1);
   paramApplicationInfo = localClassLoader;
   if (localClassLoader == null)
   {
      paramApplicationInfo = new File(f);
      if (!paramApplicationInfo.exists()) {
      paramApplicationInfo.mkdirs();
      }
      paramApplicationInfo = new DexClassLoader(str2, f, str3, MainApplication.b()getClassLoader());
      this.a.put(str1, paramApplicationInfo);
   }
   paramApplicationInfo = Class.forName(paramString, true, paramApplicationInfo).newInstance();
   return paramApplicationInfo;
}
catch (Exception paramApplicationInfo)
{
   paramApplicationInfo.printStackTrace();
}
return null;
  }

  private <T> T a(ApplicationInfo paramApplicationInfo, String paramString, Class<T> paramClass)
  {
paramApplicationInfo = a(paramApplicationInfo, paramString);
if ((paramApplicationInfo != null) && (paramClass.isInstance(paramApplicationInfo))) {
   return paramApplicationInfo;
}
throw new InstantiationError(&#34;pluginClassName：&#34; + paramString + &#34;Instance fail&#34;);
  }
/*
判断系统是否满足底层需求，判断的方法存在于插件当中
*/
  private boolean a(ApplicationInfo paramApplicationInfo)
  {
String str = paramApplicationInfo.metaData.getString(&#34;IPlugin&#34;);
if (str == null) {
   return false;
}
paramApplicationInfo = (IPlugin)a(paramApplicationInfo, str, IPlugin.class);
if (paramApplicationInfo == null) {
   return false;
}
return paramApplicationInfo.isSupport(MainApplication.b());
  }

/*
参数1：插件包
参数2：配置里写入的package名
*/
  private static boolean a(File paramFile, String paramString)
  {
try
{
   boolean bool = Arrays.equals(com.iflytek.utils.hash.b.a(MainApplication.b().getAssets().open(paramString)), com.iflytek.utils.hash.b.a(paramFile));
   return bool;
}
catch (Exception paramFile) {}
return false;
  }

  private ApplicationInfo b()
  {
int i = 0;
Object localObject1 = new File(c);
Object localObject2 = new File(d);
if ((((File)localObject1).exists()) && (((File)localObject2).exists()))
{
   localObject2 = e.b((File)localObject2);
   if (TextUtils.isEmpty((CharSequence)localObject2)) {}
}
for (boolean bool = a((File)localObject1, &#34;plugin/&#34; + (String)localObject2); bool; bool = false)
{
   localObject1 = a(c, e);
   if ((localObject1 == null) || (!a((ApplicationInfo)localObject1))) {
      break;
   }
   return localObject1;
}
for (;;)
{
   try
   {
      localObject1 = new File(d);
      e.a((File)localObject1);
      localObject2 = MainApplication.b().getAssets().list(&#34;plugin&#34;);
      int j = localObject2.length;
      if (i < j)
      {
      String str = localObject2;
      if ((!str.endsWith(&#34;.apk&#34;)) || (str.equals(&#34;empty.apk&#34;))) {
         break label217;
      }
      ApplicationInfo localApplicationInfo = d(str);
      if ((localApplicationInfo == null) || (!a(localApplicationInfo))) {
         break label217;
      }
      e.a((File)localObject1, Arrays.asList(new String[] { str }));
      return localApplicationInfo;
      }
   }
   catch (IOException localIOException)
   {
      localIOException.printStackTrace();
   }
   return null;
   label217:
   i += 1;
}
  }

  private static ApplicationInfo d(String paramString)
  {
String str1 = c;
String str2 = e;
File localFile = new File(f);
e.a(new File(str2));
e.a(localFile);
localFile.mkdirs();
com.iflytek.aichang.util.b.a(MainApplication.b(), &#34;plugin/&#34; + paramString, str1);
a.a(str1, str2);
return a(str1, str2);
  }

/*
这个是核心的接口，构造需求的接口类
*/
  public final <T> T a(Class<T> paramClass)
  {
ApplicationInfo localApplicationInfo = a();
return a(localApplicationInfo, localApplicationInfo.metaData.getString(paramClass.getSimpleName()), paramClass);
  }

/*
对外获取manifest中对应的meta-deta
*/
  public final String a(String paramString)
  {
return a().metaData.getString(paramString);
  }

  public final int b(String paramString)
  {
return a().metaData.getInt(paramString);
  }

  public final boolean c(String paramString)
  {
return a().metaData.getBoolean(paramString);
  }
}
中间都是一些跟package和application相关的API，这里就不多说了插件的两个基本核心就是，插件apk的设计和插件的工具类的实现。

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