Issue 1848 - Clean up local reference handling

jni/JniLogSystem.cpp

Index: jni/JniLogSystem.cpp
diff --git a/jni/JniLogSystem.cpp b/jni/JniLogSystem.cpp
index 275b5ef85b7d0b56a91ba9a02434448db08de437..f3771e08c274bc2f16bd18281ad3314135a42432 100644
--- a/jni/JniLogSystem.cpp
+++ b/jni/JniLogSystem.cpp
@@ -40,8 +40,9 @@ void JniLogSystemCallback::operator()(AdblockPlus::LogSystem::LogLevel logLevel,
 {
   JNIEnvAcquire env(GetJavaVM());
 
-  jclass clazz = env->GetObjectClass(GetCallbackObject());
-  jmethodID method = env->GetMethodID(clazz, "logCallback", "(" TYP("LogSystem$LogLevel") "Ljava/lang/String;Ljava/lang/String;)V");
+  jmethodID method = env->GetMethodID(
+      *JniLocalReference<jclass>(*env, env->GetObjectClass(GetCallbackObject())),
+      "logCallback", "(" TYP("LogSystem$LogLevel") "Ljava/lang/String;Ljava/lang/String;)V");
 
   // TODO: Set log level from Java and handle it here (to reduce C++->Java calls)
 
@@ -73,12 +74,12 @@ void JniLogSystemCallback::operator()(AdblockPlus::LogSystem::LogLevel logLevel,
     if (enumClass)
     {
       jfieldID enumField = env->GetStaticFieldID(enumClass, enumName, TYP("LogSystem$LogLevel"));
-      jobject jLogLevel = env->GetStaticObjectField(enumClass, enumField);
+      JniLocalReference<jobject> jLogLevel(*env, env->GetStaticObjectField(enumClass, enumField));
 
-      jstring jMessage = env->NewStringUTF(message.c_str());
-      jstring jSource = env->NewStringUTF(source.c_str());
+      JniLocalReference<jstring> jMessage(*env, env->NewStringUTF(message.c_str()));
+      JniLocalReference<jstring> jSource(*env, env->NewStringUTF(source.c_str()));
 
-      env->CallVoidMethod(GetCallbackObject(), method, jLogLevel, jMessage, jSource);
+      env->CallVoidMethod(GetCallbackObject(), method, *jLogLevel, *jMessage, *jSource);
     }
 
     CheckAndLogJavaException(*env);