Add filter to AbstractCachingViewResolver

This commit introduces a filter that specifies whether a View should be
cached by the AbstractCachingViewResolver or not.

Closes gh-22391

spring-webmvc/src/test/java/org/springframework/web/servlet/view/ViewResolverCacheFilterTest.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.servlet.view;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.util.Locale;
+import org.junit.Test;
+import org.springframework.web.servlet.View;
+
+public class ViewResolverCacheFilterTest {
+
+	private interface ViewLoader {
+		View load(String viewName);
+	}
+
+	private static class TestViewResolver extends AbstractCachingViewResolver {
+
+		private final ViewLoader viewLoader;
+
+		private TestViewResolver(ViewLoader viewLoader) {
+			this.viewLoader = viewLoader;
+		}
+
+		@Override
+		protected View loadView(String viewName, Locale locale) {
+			return viewLoader.load(viewName);
+		}
+	}
+
+	private final static String VIEW_NAME = "name";
+	private final ViewLoader viewLoader = mock(ViewLoader.class);
+	private final TestViewResolver resolver = new TestViewResolver(viewLoader);
+
+	@Test
+	public void viewWillBePlacedInCache() throws Exception {
+		resolver.setViewCacheFilter((n, v, l) -> true);
+
+		resolver.resolveViewName(VIEW_NAME, Locale.ENGLISH);
+		resolver.resolveViewName(VIEW_NAME, Locale.ENGLISH);
+
+		verify(viewLoader, times(1)).load(any());
+	}
+
+	@Test
+	public void viewWillNotBePlacedInCached() throws Exception {
+		resolver.setViewCacheFilter((n, v, l) -> false);
+
+		resolver.resolveViewName(VIEW_NAME, Locale.ENGLISH);
+		resolver.resolveViewName(VIEW_NAME, Locale.ENGLISH);
+
+		verify(viewLoader, times(2)).load(any());
+	}
+
+	@Test
+	public void verifyPassedParamsToFilter() throws Exception {
+		View view = mock(View.class);
+		when(viewLoader.load(any())).thenReturn(view);
+
+		ViewCacheFilter filter = mock(ViewCacheFilter.class);
+		resolver.setViewCacheFilter(filter);
+
+		resolver.resolveViewName(VIEW_NAME, Locale.ENGLISH);
+
+		verify(filter, times(1)).filter(eq(VIEW_NAME), eq(view), eq(Locale.ENGLISH));
+	}
+}