Use a Java trampoline when calling Java code from JNI.

This prevents the "null caller frame" error in recent
JDKs. Additionally, if running on JDK 9+, search class hierarchy for a
accessible method to invoke. This makes Arrays.asList(...).toArray()
work.

Author: LeviticusMB

src-java/node/CastingUtils.class

@@ -0,0 +1,56 @@
+package node;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+
+public abstract class MethodCallBaton {
+    public static Object newInstance(Constructor<?> ctor, Object[] args) throws Exception {
+        return ctor.newInstance(args);
+    }
+
+    public static Object invokeMethod(Method func, Object obj, Object[] args) throws Exception {
+        func.setAccessible(true);
+        return func.invoke(obj, args);
+    }
+
+    public static Object invokeMethod9(Method func, Object obj, Object[] args) throws Exception {
+        if (!func.canAccess(obj)) {
+            Method accessible = findAccessible(func, obj, func.getDeclaringClass());
+
+            if (accessible != null) {
+                func = accessible;
+            }
+        }
+
+        return func.invoke(obj, args);
+    }
+
+    private static Method findAccessible(Method func, Object obj, Class<?> clazz) {
+        Method accessible = null;
+
+        if (clazz != null) {
+            try {
+                accessible = clazz.getMethod(func.getName(), func.getParameterTypes());
+                accessible = accessible.canAccess(obj) ? accessible : null;
+            } catch (Exception ignored) {
+                accessible = null;
+            }
+
+            if (accessible == null) {
+                accessible = findAccessible(func, obj, clazz.getSuperclass());
+            }
+
+            if (accessible == null) {
+                for (Class<?> iface : clazz.getInterfaces()) {
+                    accessible = findAccessible(func, obj, iface);
+
+                    if (accessible != null) {
+                        break;
+                    }
+                }
+            }
+        }
+
+        return accessible;
+    }
+}

src-java/node/MethodCallBaton.class

@@ -119,13 +119,12 @@ v8::Local<v8::Value> MethodCallBaton::resultsToV8(JNIEnv *env) {
 }
 
 void NewInstanceBaton::ExecuteInternal(JNIEnv* env) {
-  jclass constructorClazz = env->FindClass("java/lang/reflect/Constructor");
-  jmethodID constructor_newInstance = env->GetMethodID(constructorClazz, "newInstance", "([Ljava/lang/Object;)Ljava/lang/Object;");
-
-  //printf("invoke: %s\n", javaMethodCallToString(env, m_method, constructor_newInstance, m_args).c_str());
+  jclass batonClazz = env->FindClass("node/MethodCallBaton");
+  jmethodID newInstance = env->GetStaticMethodID(batonClazz, "newInstance", "(Ljava/lang/reflect/Constructor;[Ljava/lang/Object;)Ljava/lang/Object;");
 
   jarray args = javaGetArgsForConstructor(env, m_method, m_args);
-  jobject result = env->CallObjectMethod(m_method, constructor_newInstance, args);
+  jobject result = env->CallStaticObjectMethod(batonClazz, newInstance, m_method, args);
+
   if(env->ExceptionCheck()) {
     jthrowable ex = env->ExceptionOccurred();
     env->ExceptionClear();
@@ -138,8 +137,6 @@ void NewInstanceBaton::ExecuteInternal(JNIEnv* env) {
 }
 
 void StaticMethodCallBaton::ExecuteInternal(JNIEnv* env) {
-  jmethodID method_invoke = getMethodInvokeMethodId(env);
-
   /*
   printf("calling %s\n", javaObjectToString(env, m_method).c_str());
   printf("arguments\n");
@@ -150,8 +147,11 @@ void StaticMethodCallBaton::ExecuteInternal(JNIEnv* env) {
   }
   */
 
+  jclass batonClazz = env->FindClass("node/MethodCallBaton");
+  jmethodID invokeMethod = env->GetStaticMethodID(batonClazz, env->GetVersion() >= 0x90000 ? "invokeMethod9" : "invokeMethod", "(Ljava/lang/reflect/Method;Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;");
+
   jarray args = javaGetArgsForMethod(env, m_method, m_args);
-  jobject result = env->CallObjectMethod(m_method, method_invoke, NULL, args);
+  jobject result = env->CallStaticObjectMethod(batonClazz, invokeMethod, m_method, NULL, args);
 
   if(env->ExceptionCheck()) {
     jthrowable ex = env->ExceptionOccurred();
@@ -165,18 +165,19 @@ void StaticMethodCallBaton::ExecuteInternal(JNIEnv* env) {
 }
 
 void InstanceMethodCallBaton::ExecuteInternal(JNIEnv* env) {
-  jmethodID method_invoke = getMethodInvokeMethodId(env);
-
   /*
   printf("calling %s\n", javaObjectToString(env, m_method).c_str());
   printf("arguments\n");
   for(int i=0; i<env->GetArrayLength(m_args); i++) {
     printf("  %s\n", javaObjectToString(env, env->GetObjectArrayElement((jobjectArray)m_args, i)).c_str());
   }
   */
-  
+
+  jclass batonClazz = env->FindClass("node/MethodCallBaton");
+  jmethodID invokeMethod = env->GetStaticMethodID(batonClazz, env->GetVersion() >= 0x90000 ? "invokeMethod9" : "invokeMethod", "(Ljava/lang/reflect/Method;Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;");
+
   jarray args = javaGetArgsForMethod(env, m_method, m_args);
-  jobject result = env->CallObjectMethod(m_method, method_invoke, m_javaObject->getObject(), args);
+  jobject result = env->CallStaticObjectMethod(batonClazz, invokeMethod, m_method, m_javaObject->getObject(), args);
 
   if(env->ExceptionCheck()) {
     jthrowable ex = env->ExceptionOccurred();