Support stub APK loading down to Android 5.0

stub/src/main/java/com/topjohnwu/magisk/ClassLoaders.java

@@ -0,0 +1,33 @@
+package com.topjohnwu.magisk;
+
+import com.topjohnwu.magisk.utils.DynamicClassLoader;
+
+import java.io.File;
+
+class InjectedClassLoader extends DynamicClassLoader {
+
+    InjectedClassLoader(File apk) {
+        super(apk,
+                /* Use the base classloader as we do not want stub
+                 * APK classes accessible from the main app */
+                Object.class.getClassLoader());
+    }
+
+    @Override
+    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+        return super.loadClass(Mapping.get(name), resolve);
+    }
+}
+
+class RedirectClassLoader extends ClassLoader {
+
+    RedirectClassLoader() {
+        super(RedirectClassLoader.class.getClassLoader());
+    }
+
+    @Override
+    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+        Class<?> clz = Mapping.internalMap.get(name);
+        return clz == null ? super.loadClass(name, resolve) : clz;
+    }
+}