Deconstructed APK prototyping

apk/hijack/org/chromium/deconstructed/Reflect.java

+package org.chromium.deconstructed;
+
+import java.lang.reflect.Array;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+
+public class Reflect {
+    public static Object invokeMethod(Object instance, String name, Object... params)
+            throws NoSuchMethodException, InvocationTargetException {
+        return invokeMethodInternal(instance.getClass(), instance, name, params);
+    }
+
+    public static Object invokeStaticMethod(String className, String name, Object... params)
+            throws NoSuchMethodException, InvocationTargetException, ClassNotFoundException {
+        Class<?> clazz = Class.forName(className);
+        return invokeMethodInternal(clazz, null, name, params);
+    }
+
+    public static Object newInstance(ClassLoader loader, String className, Object... params)
+            throws NoSuchMethodException, InstantiationException, InvocationTargetException {
+        Class clazz = (Class)invokeMethod(loader, "findClass", className);
+        Constructor constructor = findConstructor(clazz, params);
+        try {
+            constructor.setAccessible(true);
+            return constructor.newInstance(params);
+        } catch (IllegalAccessException e) {
+            // This shouldn't happen.
+        }
+        return null;
+    }
+
+    public static void setField(Object instance, String name, Object val)
+            throws NoSuchFieldException {
+        Field field = findField(instance, name);
+        try {
+            field.setAccessible(true);
+            field.set(instance, val);
+        } catch (IllegalAccessException e) {
+            // This shouldn't happen.
+        }
+    }
+
+    public static Object getField(Object instance, String name) throws NoSuchFieldException {
+        Field field = findField(instance, name);
+        try {
+            field.setAccessible(true);
+            return field.get(instance);
+        } catch (IllegalAccessException e) {
+            // This shouldn't happen.
+        }
+        return null;
+    }
+
+    public static Object[] concatArrays(Object[] left, Object[] right) {
+        Object[] result = (Object[]) (Array.newInstance(
+                left.getClass().getComponentType(), left.length + right.length));
+        System.arraycopy(left, 0, result, 0, left.length);
+        System.arraycopy(right, 0, result, left.length, right.length);
+        return result;
+    }
+
+    private static Object invokeMethodInternal(Class<?> clazz, Object instance, String name, Object... params)
+            throws NoSuchMethodException, InvocationTargetException {
+        Method method = findMethod(clazz, name, params);
+        try {
+            method.setAccessible(true);
+            return method.invoke(instance, params);
+        } catch (IllegalAccessException e) {
+            // This shouldn't happen.
+        }
+        return null;
+    }
+
+    private static Method findMethod(Class<?> clazz, String name, Object... params)
+            throws NoSuchMethodException {
+        for (; clazz != null; clazz = clazz.getSuperclass()) {
+            for (Method method : clazz.getDeclaredMethods()) {
+                if (method.getName().equals(name) && isMethodCallableWith(method, params)) {
+                    return method;
+                }
+            }
+        }
+        throw new NoSuchMethodException("Method " + name + " with parameters "
+                + Arrays.asList(params) + " not found in " + clazz);
+    }
+
+    private static boolean isMethodCallableWith(Method method, Object... params) {
+        Class<?>[] parameterTypes = method.getParameterTypes();
+        if (params.length != parameterTypes.length) return false;
+        for (int i = 0; i < params.length; i++) {
+            if (!parameterTypes[i].isAssignableFrom(params[i].getClass())) return false;
+        }
+        return true;
+    }
+
+    private static Constructor findConstructor(Class clazz, Object... params)
+            throws NoSuchMethodException {
+        for (Constructor constructor : clazz.getDeclaredConstructors()) {
+            if (isConstructorCallableWith(constructor, params)) {
+                return constructor;
+            }
+        }
+        throw new NoSuchMethodException("Constructor with parameters " + Arrays.asList(params)
+                + " not found in " + clazz);
+    }
+
+    private static boolean isConstructorCallableWith(Constructor constructor, Object... params) {
+        Class<?>[] parameterTypes = constructor.getParameterTypes();
+        if (params.length != parameterTypes.length) return false;
+        for (int i = 0; i < params.length; i++) {
+            if (!parameterTypes[i].isAssignableFrom(params[i].getClass())) return false;
+        }
+        return true;
+    }
+
+    private static Field findField(Object instance, String name) throws NoSuchFieldException {
+        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
+            try {
+                return clazz.getDeclaredField(name);
+            } catch (NoSuchFieldException e) {
+            }
+        }
+        throw new NoSuchFieldException("Field " + name + " not found in " + instance.getClass());
+    }
+}