fix jni reference leaks (issue #72)

Author: Mihail Slavchev

src/jni/ArgConverter.cpp

@@ -179,9 +179,9 @@ Handle<Array> ArgConverter::ConvertJavaArgsToJsArgs(jobjectArray args)
 	int jArrayIndex = 0;
 	for (int i = 0; i < argc; i++)
 	{
-		jobject argTypeIDObj = env.GetObjectArrayElement(args, jArrayIndex++);
-		jobject arg = env.GetObjectArrayElement(args, jArrayIndex++);
-		jobject argJavaClassPath = env.GetObjectArrayElement(args, jArrayIndex++);
+		JniLocalRef argTypeIDObj(env.GetObjectArrayElement(args, jArrayIndex++));
+		JniLocalRef arg(env.GetObjectArrayElement(args, jArrayIndex++));
+		JniLocalRef argJavaClassPath(env.GetObjectArrayElement(args, jArrayIndex++));
 
 		jint length;
 		jint argTypeID = ObjectToInt(argTypeIDObj);
@@ -246,7 +246,7 @@ Handle<String> ArgConverter::jcharToV8String(jchar value)
 {
 	JEnv env;
 
-	jstring str = env.NewString(&value, 1);
+	JniLocalRef str(env.NewString(&value, 1));
 	jboolean bol = true;
 	const char* resP = env.GetStringUTFChars(str, &bol);
 	auto v8String = ConvertToV8String(resP, 1);

src/jni/ArrayElementAccessor.cpp

@@ -52,7 +52,7 @@ Handle<Value> ArrayElementAccessor::GetArrayElement(const Handle<Object>& array,
 		jcharArray charArr = reinterpret_cast<jcharArray>(arr);
 		jchar charArrValue;
 		env.GetCharArrayRegion(charArr, startIndex, length, &charArrValue);
-		jstring s = env.NewString(&charArrValue, 1);
+		JniLocalRef s(env.NewString(&charArrValue, 1));
 		const char* singleChar = env.GetStringUTFChars(s, &isCopy);
 		value = CheckForArrayAccessException(env, elementSignature, singleChar);
 		env.ReleaseStringUTFChars(s, singleChar);
@@ -129,7 +129,7 @@ void ArrayElementAccessor::SetArrayElement(const Handle<Object>& array, uint32_t
 	else if (elementSignature == "C")
 	{
 		String::Utf8Value utf8(value->ToString());
-		jstring s = env.NewString((jchar*) *utf8, 1);
+		JniLocalRef s(env.NewString((jchar*) *utf8, 1));
 		const char* singleChar = env.GetStringUTFChars(s, &isCopy);
 		jchar charElementValue = *singleChar;
 		env.ReleaseStringUTFChars(s, singleChar);

src/jni/FieldAccessor.cpp

@@ -106,7 +106,7 @@ Handle<Value> FieldAccessor::GetJavaField(const Handle<Object>& target, FieldCal
 					result = env.GetCharField(targetJavaObject, fieldId);
 				}
 
-				jstring str = env.NewString(&result, 1);
+				JniLocalRef str(env.NewString(&result, 1));
 				jboolean bol = true;
 				const char* resP = env.GetStringUTFChars(str, &bol);
 				env.ReleaseStringUTFChars(str, resP);