Fix ParameterizedType + contextClass support in Jackson converter

Issue: SPR-14470

Author: sdeleuze

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -17,6 +17,7 @@
 package org.springframework.http.converter.json;
 
 import java.io.IOException;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.nio.charset.Charset;
@@ -311,11 +312,37 @@ protected void writeSuffix(JsonGenerator generator, Object object) throws IOExce
 	 */
 	protected JavaType getJavaType(Type type, Class<?> contextClass) {
 		TypeFactory typeFactory = this.objectMapper.getTypeFactory();
-		if (type instanceof TypeVariable && contextClass != null) {
-			ResolvableType resolvedType = resolveVariable(
-					(TypeVariable<?>) type, ResolvableType.forClass(contextClass));
-			if (resolvedType != ResolvableType.NONE) {
-				return typeFactory.constructType(resolvedType.resolve());
+		if (contextClass != null) {
+			ResolvableType resolvedType = ResolvableType.forType(type);
+			if (type instanceof TypeVariable) {
+				ResolvableType resolvedTypeVariable = resolveVariable(
+						(TypeVariable<?>) type, ResolvableType.forClass(contextClass));
+				if (resolvedTypeVariable != ResolvableType.NONE) {
+					return typeFactory.constructType(resolvedTypeVariable.resolve());
+				}
+			}
+			else if (type instanceof ParameterizedType && resolvedType.hasUnresolvableGenerics()) {
+				ParameterizedType parameterizedType = (ParameterizedType) type;
+				Class<?>[] generics = new Class<?>[parameterizedType.getActualTypeArguments().length];
+				Type[] typeArguments = parameterizedType.getActualTypeArguments();
+				for (int i = 0; i < typeArguments.length; i++) {
+					Type typeArgument = typeArguments[i];
+					if (typeArgument instanceof TypeVariable) {
+						ResolvableType resolvedTypeArgument = resolveVariable(
+								(TypeVariable<?>) typeArgument, ResolvableType.forClass(contextClass));
+						if (resolvedTypeArgument != ResolvableType.NONE) {
+							generics[i] = resolvedTypeArgument.resolve();
+						}
+						else {
+							generics[i] = ResolvableType.forType(typeArgument).resolve();
+						}
+					}
+					else {
+						generics[i] = ResolvableType.forType(typeArgument).resolve();
+					}
+				}
+				return typeFactory.constructType(ResolvableType.
+						forClassWithGenerics(resolvedType.getRawClass(), generics).getType());
 			}
 		}
 		return typeFactory.constructType(type);

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestResponseBodyMethodProcessorTests.java

@@ -240,6 +240,29 @@ public void resolveArgumentTypeVariable() throws Exception {
 		assertEquals("Jad", result.getName());
 	}
 
+	@Test  // SPR-14470
+	public void resolveParameterizedWithTypeVariableArgument() throws Exception {
+		Method method = MyParameterizedControllerWithList.class.getMethod("handleDto", List.class);
+		HandlerMethod handlerMethod = new HandlerMethod(new MySimpleParameterizedController(), method);
+		MethodParameter methodParam = handlerMethod.getMethodParameters()[0];
+
+		String content = "[{\"name\" : \"Jad\"}, {\"name\" : \"Robert\"}]";
+		this.servletRequest.setContent(content.getBytes("UTF-8"));
+		this.servletRequest.setContentType(MediaType.APPLICATION_JSON_VALUE);
+
+		List<HttpMessageConverter<?>> converters = new ArrayList<>();
+		converters.add(new MappingJackson2HttpMessageConverter());
+		RequestResponseBodyMethodProcessor processor = new RequestResponseBodyMethodProcessor(converters);
+
+		@SuppressWarnings("unchecked")
+		List<SimpleBean> result = (List<SimpleBean>)
+				processor.resolveArgument(methodParam, container, request, factory);
+
+		assertNotNull(result);
+		assertEquals("Jad", result.get(0).getName());
+		assertEquals("Robert", result.get(1).getName());
+	}
+
 	@Test  // SPR-11225
 	public void resolveArgumentTypeVariableWithNonGenericConverter() throws Exception {
 		Method method = MyParameterizedController.class.getMethod("handleDto", Identifiable.class);
@@ -725,6 +748,17 @@ private interface Identifiable extends Serializable {
 		void setId(Long id);
 	}
 
+	@SuppressWarnings("unused")
+	private static abstract class MyParameterizedControllerWithList<DTO extends Identifiable> {
+
+		public void handleDto(@RequestBody List<DTO> dto) {
+		}
+	}
+
+	@SuppressWarnings("unused")
+	private static class MySimpleParameterizedControllerWithList extends MyParameterizedControllerWithList<SimpleBean> {
+	}
+
 
 	@SuppressWarnings({ "serial" })
 	private static class SimpleBean implements Identifiable {