attempt to keep responseBodyAdvice intact on handler using reflection…

… as the API is really strict

monitorjbl#55

spring-json-view/src/main/java/com/monitorjbl/json/JsonViewResponseProcessor.java

@@ -1,12 +1,13 @@
 package com.monitorjbl.json;
 
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor;
 
 import java.util.List;
 
 public class JsonViewResponseProcessor extends RequestResponseBodyMethodProcessor {
-  public JsonViewResponseProcessor(List<HttpMessageConverter<?>> messageConverters) {
-    super(messageConverters);
+  public JsonViewResponseProcessor(List<HttpMessageConverter<?>> messageConverters, List<Object> responseBodyAdvice) {
+    super(messageConverters, null, responseBodyAdvice);
   }
 }

spring-json-view/src/main/java/com/monitorjbl/json/JsonViewReturnValueHandler.java

@@ -16,8 +16,8 @@ public class JsonViewReturnValueHandler implements HandlerMethodReturnValueHandl
   private final HandlerMethodReturnValueHandler delegate;
   private final DefaultView defaultView;
 
-  public JsonViewReturnValueHandler(List<HttpMessageConverter<?>> converters, DefaultView defaultView) {
-    this.delegate = new JsonViewResponseProcessor(converters);
+  public JsonViewReturnValueHandler(HandlerMethodReturnValueHandler delegate, DefaultView defaultView) {
+    this.delegate = delegate;
     this.defaultView = defaultView;
   }
 

spring-json-view/src/main/java/com/monitorjbl/json/JsonViewSupportFactoryBean.java

@@ -1,5 +1,6 @@
 package com.monitorjbl.json;
 
+import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
@@ -80,13 +81,33 @@ private void decorateHandlers(List<HandlerMethodReturnValueHandler> handlers) {
       int index = handlers.indexOf(handler);
       if(handler instanceof HttpEntityMethodProcessor) {
         handlers.set(index, new JsonViewHttpEntityMethodProcessor(converters));
-      } else if(handler instanceof RequestResponseBodyMethodProcessor) {
-        handlers.set(index, new JsonViewReturnValueHandler(converters, defaultView));
+      } else if(handler instanceof HandlerMethodReturnValueHandler) {
+        HandlerMethodReturnValueHandler valueHandler = handlers.get(index);
+        List<Object> responseBodyAdvice = (List<Object>) get(valueHandler,"advice");
+        HandlerMethodReturnValueHandler delegate = new JsonViewResponseProcessor(converters, responseBodyAdvice);
+        handlers.set(index, new JsonViewReturnValueHandler(delegate,  defaultView));
         break;
       }
     }
   }
 
+  //reflection unfortunately
+  public static Object get(Object obj, String fieldName) {
+    Class<?> clazz = obj.getClass();
+    while (clazz != null) {
+      try {
+        Field field = clazz.getDeclaredField(fieldName);
+        field.setAccessible(true);
+        return field.get(obj);
+      } catch (NoSuchFieldException e) {
+        clazz = clazz.getSuperclass();
+      } catch (Exception e) {
+        throw new IllegalStateException(e);
+      }
+    }
+    return null;
+  }
+
 
   /**
    * Registering custom serializer allows to the JSonView to deal with custom serializations for certains field types.<br>