Android中的动态类加载答案

【问题标题】：Dynamic class loading in AndroidAndroid中的动态类加载
【发布时间】：2015-12-26 06:08:07
【问题描述】：

我想为我的 Android 应用程序注入功能。但是我一直在遭受'java.lang.ClassNotFoundException'。我错过了什么？

简单的类（只是一个.class文件）
布局和资源
活动

首先我想做1。但是实现的方法太多了，我很困惑如何实现。

假设：

1.文件下载到本地数据仓库。

2.targetClassName 是 com.example.mari.myandroid.TestDinamicLoad。

3.SDK & Build Tools 版本，（无proguard） compileSdkVersion 22 buildToolsVersion "21.1.2"

模式 A：使用 URLClassLoader

编译：gradle 编译，这只是原始类文件

网址：https://drive.google.com/file/d/0B0Hrot21k8nYZ2pWNXBBMU5Qd2M/view?usp=sharing

    private void urlLoader(final File file){
        try {
            URL myurl[] = {new URL("file:" + file.toString())};
            URLClassLoader x = new URLClassLoader(myurl);
            Class c = x.loadClass(this.targetClassName);
            for (Field f : c.getDeclaredFields()) {
                Log.v(TAG, f.getName() + " : " + f.toString());
            }
        }catch(Exception e){
            Log.v(TAG, e.toString());
        }
    }

模式 B：使用 dexLoader

编译：

    javac -classpath /Applications/adt-bundle-mac/sdk/platforms/android-22/android.jar TestDinamicLoad.java
    dx --dex --output TestDinamicLoad.jar TestDinamicLoad.java

网址： https://drive.google.com/file/d/0B0Hrot21k8nYdG9wdHhiOWJIVE0/view?usp=sharing

    private void dexLoader(final File file){
    try {
        Context ctx     = getApplicationContext();
        String         dex_dir = ctx.getDir("dex", 0).getAbsolutePath();
        ClassLoader    parent  = getClass().getClassLoader();
        DexClassLoader loader  = new DexClassLoader(file.getPath(), dex_dir, null, parent);
        Class          c       = loader.loadClass(this.targetClassName);
        Object         o       = c.newInstance();
        Method m       = c.getMethod("func");

        m.invoke(o);
    } catch (Exception e) {
        Log.v(TAG, e.toString());
    }

}

错误：

    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani: urlLoader------
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani: java.lang.ClassNotFoundException: com.example.mari.myandroid.TestDinamicLoad
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.net.URLClassLoader.findClass(URLClassLoader.java:753)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity.urlLoader(MainActivity.java:109)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity.access$200(MainActivity.java:23)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity$1.postExecute(MainActivity.java:69)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.AsyncFileDownload.doInBackground(AsyncFileDownload.java:78)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.AsyncFileDownload.doInBackground(AsyncFileDownload.java:19)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at android.os.AsyncTask$2.call(AsyncTask.java:288)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.Thread.run(Thread.java:818)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:  Suppressed: java.lang.ClassNotFoundException: Didn't find class "com.example.mari.myandroid.TestDinamicLoad" on path: DexPathList[[directory "."],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:          ... 12 more
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:      Suppressed: java.lang.ClassNotFoundException: com.example.mari.myandroid.TestDinamicLoad
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.Class.classForName(Native Method)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:              ... 13 more
    12-26 23:20:34.817 19078-19264/com.example.mari.myandorid2 V/murotani:  Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available


    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani: dexLoader------
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani: java.lang.ClassNotFoundException: Didn't find class "com.example.mari.myandroid.TestDinamicLoad" on path: DexPathList[[zip file "/data/data/com.example.mari.myandorid2/files/TestDinamicLoad.class"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity.dexLoader(MainActivity.java:91)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity.access$300(MainActivity.java:23)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity$1.postExecute(MainActivity.java:70)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.AsyncFileDownload.doInBackground(AsyncFileDownload.java:78)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.AsyncFileDownload.doInBackground(AsyncFileDownload.java:19)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at android.os.AsyncTask$2.call(AsyncTask.java:288)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.Thread.run(Thread.java:818)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:  Suppressed: java.io.IOException: Expected valid zip or dex file: '/data/data/com.example.mari.myandorid2/files/TestDinamicLoad.class'
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexFile.openDexFileNative(Native Method)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexFile.openDexFile(DexFile.java:295)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexFile.<init>(DexFile.java:111)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexFile.loadDex(DexFile.java:151)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexPathList.loadDexFile(DexPathList.java:265)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexPathList.makeDexElements(DexPathList.java:231)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexPathList.<init>(DexPathList.java:109)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.BaseDexClassLoader.<init>(BaseDexClassLoader.java:48)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.DexClassLoader.<init>(DexClassLoader.java:57)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at com.example.mari.myandorid2.MainActivity.dexLoader(MainActivity.java:90)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:          ... 10 more
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:  Suppressed: java.lang.ClassNotFoundException: Didn't find class "com.example.mari.myandroid.TestDinamicLoad" on path: DexPathList[[zip file "/data/app/com.example.mari.myandorid2-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:          ... 12 more
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:      Suppressed: java.lang.ClassNotFoundException: com.example.mari.myandroid.TestDinamicLoad
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.Class.classForName(Native Method)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:     at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:              ... 13 more
    12-26 23:20:34.837 19078-19264/com.example.mari.myandorid2 V/murotani:  Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available

参考： ClassNotFoundException during Dynamic Class loading in android http://tech.co/android-security-2014-07 http://larshamren.blogspot.jp/2012/02/android-dynamically-loading-classes.html

【问题讨论】：

动态加载一个Activity？我不相信这是可能的。
对于第 1 点，请发布异常的完整堆栈跟踪，并说明是针对模式 A 还是 B。关于第 2 点，您可以轻松添加所需的所有 XML 文件和资源, 但在构建过程开始之前执行此操作，因为在 APK XML 资源中是二进制格式。第 3 点，没有技巧是不可能的：安装应用程序时，清单中声明的所有活动都“注册”。因此，如果您在运行时加载安装时清单中不存在的 Activity，您将收到异常。
见dynamic load framework for android
也许这对你有帮助github.com/lukeFalsina/Grab-n-Run

标签： java android

【解决方案1】：

我想你想要的是动态加载一个 apk：

动态负载类
动态加载android资源
动态注册活动

这些现已在Small@github 上提供，您可以尝试并玩得开心。

【讨论】：