android - 从 sd 卡中的库加载片段时，Android 系统无法在活动娱乐时找到片段？

Question

我已经从外部库中加载了一个片段，成功地在 sd 卡中可用，但是当 android 系统重新创建活动时，我的应用程序崩溃，因为 android 系统无法找到外部库中可用的片段类。

从外部 apk 加载片段的代码。

  final String libPath = Environment.getExternalStorageDirectory() + "/lib.apk";
        final File tmpDir = getDir("dex", 0);

        final File tmpDir1 = new File(libPath);
        Log.d(TAG, ""+tmpDir1.exists());

        final DexClassLoader classloader = new DexClassLoader(libPath, tmpDir.getAbsolutePath(), null, this.getClass().getClassLoader());
        final Class<Fragment> classToLoad = (Class<Fragment>) classloader.loadClass("com.example.sujeetkumarsinha.librarycode2.MyFragment");

错误代码

    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sujeetkumarsinha.dynamic_code_run/com.example.sujeetkumarsinha.myapplication.MainActivity}: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.sujeetkumarsinha.librarycode2.MyFragment: make sure class name exists, is public, and has an empty constructor that is public
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2678)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2743)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4560)
at android.app.ActivityThread.-wrap19(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1496)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6165)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:778)
Caused by: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.sujeetkumarsinha.librarycode2.MyFragment: make sure class name exists, is public, and has an empty constructor that is public
at android.support.v4.app.Fragment.instantiate(Fragment.java:449)
at android.support.v4.app.FragmentContainer.instantiate(FragmentContainer.java:33)
at android.support.v4.app.FragmentState.instantiate(Fragment.java:110)
at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:2940)
at android.support.v4.app.FragmentController.restoreAllState(FragmentController.java:149)
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:287)
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:85)
at com.example.sujeetkumarsinha.myapplication.MainActivity.onCreate(MainActivity.java:26)
at android.app.Activity.performCreate(Activity.java:6687)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1140)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2631)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2743) 
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4560) 
at android.app.ActivityThread.-wrap19(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1496) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6165) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:778) 
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.sujeetkumarsinha.librarycode2.MyFragment" on path: DexPathList[[zip file "/data/app/com.example.sujeetkumarsinha.dynamic_code_run-1/base.apk"],nativeLibraryDirectories=[/data/app/com.example.sujeetkumarsinha.dynamic_code_run-1/lib/arm, /system/lib, /vendor/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.support.v4.app.Fragment.instantiate(Fragment.java:439)
at android.support.v4.app.FragmentContainer.instantiate(FragmentContainer.java:33) 
at android.support.v4.app.FragmentState.instantiate(Fragment.java:110) 
at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:2940) 
at android.support.v4.app.FragmentController.restoreAllState(FragmentController.java:149) 
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:287) 
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:85) 
at com.example.sujeetkumarsinha.myapplication.MainActivity.onCreate(MainActivity.java:26) 
at android.app.Activity.performCreate(Activity.java:6687) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1140) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2631) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2743) 
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4560) 
at android.app.ActivityThread.-wrap19(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1496) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6165) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:778) 

标签： android