加固前奏1-替换classloader

使用反射实现替换classLoader
1.获取"android.app.ActivityThread"中的"mPackages" ；

定义为arraymap<String,weakReference<LoadedApk>> mPackages

            c = Class.forName("android.app.ActivityThread");
            Field field1 = c.getDeclaredField("mPackages");
            field1.setAccessible(true);
            Object currentActivityThread = c.getMethod("currentActivityThread").invoke(null);

            ArrayMap map =(ArrayMap) field1.get(currentActivityThread);

2.获取"android.app.LoadedApk"，"mClassLoader"的属性；

将1中的WeakReference获取的对象传递进去获取LoadedApk，设置其值为自定义的dexClassLoader。

            c = Class.forName("android.app.LoadedApk");
            Field field = c.getDeclaredField("mClassLoader");
            field.setAccessible(true);
            field.set(weakReference.get(), classLoader);