如何使用反射检查加载了不同 ClassLoader 的 class 的非静态字段？

Question

我正在使用一个子 URLClassLoader 加载一个 android.jar，它可以在运行时在 Android SDK (sdk/platforms/) 中找到，然后我使用Google 用于检查我加载的新类的反射库。但是，似乎使用以下代码，我只能检查静态字段；我还想检查实例字段。（虽然我对方法没有问题！）

Path jarPath = fs.getPath("/android-sdk-macosx/platforms/android-10/android.jar");
URL[] urls = new URL[]{jarPath.toUri().toURL()};
Reflections r = new Reflections(new ConfigurationBuilder().setUrls(urls).setScanners(
    new SubTypesScanner(false)
));

URLClassLoader cl = URLClassLoader.newInstance(urls, ClassLoader.getSystemClassLoader());
for (String cls : r.getAllTypes()) {
    System.out.println(cls);
    Class<?> c = cl.loadClass(cls);
    Field[] allFields = c.getDeclaredFields();
    for (Field f : allFields) {
        System.out.println('\t' + (f.getModifiers() & Modifier.STATIC) + " " + f.getName());
    }
}

例如，当上面的代码检查android.view.View时，它只打印以下内容：

android.view.View
8 VIEW_LOG_TAG
8 NO_ID
8 VISIBLE
8 INVISIBLE
8 GONE
8 DRAWING_CACHE_QUALITY_LOW
8 DRAWING_CACHE_QUALITY_HIGH
8 DRAWING_CACHE_QUALITY_AUTO
8 SCROLLBARS_INSIDE_OVERLAY
8 SCROLLBARS_INSIDE_INSET
8 SCROLLBARS_OUTSIDE_OVERLAY
8 SCROLLBARS_OUTSIDE_INSET
8 KEEP_SCREEN_ON
8 SOUND_EFFECTS_ENABLED
8 HAPTIC_FEEDBACK_ENABLED
8 FOCUSABLES_ALL
8 FOCUSABLES_TOUCH_MODE
8 FOCUS_BACKWARD
8 FOCUS_FORWARD
8 FOCUS_LEFT
8 FOCUS_UP
8 FOCUS_RIGHT
8 FOCUS_DOWN
8 EMPTY_STATE_SET
8 ENABLED_STATE_SET
8 FOCUSED_STATE_SET
8 SELECTED_STATE_SET
8 WINDOW_FOCUSED_STATE_SET
8 ENABLED_FOCUSED_STATE_SET
8 ENABLED_SELECTED_STATE_SET
8 ENABLED_WINDOW_FOCUSED_STATE_SET
8 FOCUSED_SELECTED_STATE_SET
8 FOCUSED_WINDOW_FOCUSED_STATE_SET
8 SELECTED_WINDOW_FOCUSED_STATE_SET
8 ENABLED_FOCUSED_SELECTED_STATE_SET
8 ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET
8 ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_SELECTED_STATE_SET
8 PRESSED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_FOCUSED_STATE_SET
8 PRESSED_FOCUSED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_FOCUSED_SELECTED_STATE_SET
8 PRESSED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_ENABLED_STATE_SET
8 PRESSED_ENABLED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_ENABLED_SELECTED_STATE_SET
8 PRESSED_ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_ENABLED_FOCUSED_STATE_SET
8 PRESSED_ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET
8 PRESSED_ENABLED_FOCUSED_SELECTED_STATE_SET
8 PRESSED_ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET
8 OVER_SCROLL_ALWAYS
8 OVER_SCROLL_IF_CONTENT_SCROLLS
8 OVER_SCROLL_NEVER

But there is obviously more to it!

我做错了什么？

Answer 1

通过反编译器将 jar 扔掉后，发现 SDK 中的 android.jar 只是一个空的 shell，因此 Eclipse 和 IntelliJ 等 IDE 可以使用较小的 jar 来帮助自动完成。代码很好，但我需要检查完整的罐子。我找到了一个 Github 存储这些完整罐子的存储库：https://github.com/Sable/android-platforms，如果有人感兴趣的话。

如何使用反射检查加载了不同 ClassLoader 的 class 的非静态字段？

How to use Reflection to inspect non-static fields of a class that is loaded with a different ClassLoader?

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