android 扫描某个包下的全部class文件

public static List<Class<?>> scan(Context ctx, String entityPackage) {		List<Class<?>> classes = new ArrayList<Class<?>>();		try {			PathClassLoader classLoader = (PathClassLoader) Thread					.currentThread().getContextClassLoader();			DexFile dex = new DexFile(ctx.getPackageResourcePath());			Enumeration<String> entries = dex.entries();			while (entries.hasMoreElements()) {				String entryName = entries.nextElement();				if (entryName.contains(entityPackage)) {					Class<?> entryClass = Class.forName(entryName, true,classLoader);//疑问：Class.forName(entryName);这种方式不知道为什么返回null，哪位大神知道原因，请指点一下小弟吧  感激不尽					DatabaseTable annotation = entryClass.getAnnotation(DatabaseTable.class);					if (annotation != null) {						classes.add(entryClass);					}				}			}		} catch (Exception e) {			e.printStackTrace();		}		return classes;	}

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