Avoid reflection when creating instances of well-known View classes

Closes gh-25847

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/UrlBasedViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -94,9 +94,12 @@ public class UrlBasedViewResolver extends ViewResolverSupport
 
 
 	/**
-	 * Set the view class to instantiate through {@link #createView(String)}.
+	 * Set the view class that should be used to create views.
 	 * @param viewClass a class that is assignable to the required view class
-	 * which by default is AbstractUrlBasedView
+	 * (by default: AbstractUrlBasedView)
+	 * @see #requiredViewClass()
+	 * @see #instantiateView()
+	 * @see AbstractUrlBasedView
 	 */
 	public void setViewClass(@Nullable Class<?> viewClass) {
 		if (viewClass != null && !requiredViewClass().isAssignableFrom(viewClass)) {
@@ -109,21 +112,13 @@ public class UrlBasedViewResolver extends ViewResolverSupport
 
 	/**
 	 * Return the view class to be used to create views.
+	 * @see #setViewClass
 	 */
 	@Nullable
 	protected Class<?> getViewClass() {
 		return this.viewClass;
 	}
 
-	/**
-	 * Return the required type of view for this resolver.
-	 * This implementation returns {@link AbstractUrlBasedView}.
-	 * @see AbstractUrlBasedView
-	 */
-	protected Class<?> requiredViewClass() {
-		return AbstractUrlBasedView.class;
-	}
-
 	/**
 	 * Set the prefix that gets prepended to view names when building a URL.
 	 */
@@ -265,6 +260,29 @@ public class UrlBasedViewResolver extends ViewResolverSupport
 		return (viewNames == null || PatternMatchUtils.simpleMatch(viewNames, viewName));
 	}
 
+	/**
+	 * Return the required type of view for this resolver.
+	 * This implementation returns {@link AbstractUrlBasedView}.
+	 * @see #instantiateView()
+	 * @see AbstractUrlBasedView
+	 */
+	protected Class<?> requiredViewClass() {
+		return AbstractUrlBasedView.class;
+	}
+
+	/**
+	 * Instantiate the specified view class.
+	 * <p>The default implementation uses reflection to instantiate the class.
+	 * @return a new instance of the view class
+	 * @since 5.3
+	 * @see #setViewClass
+	 */
+	protected AbstractUrlBasedView instantiateView() {
+		Class<?> viewClass = getViewClass();
+		Assert.state(viewClass != null, "No view class");
+		return (AbstractUrlBasedView) BeanUtils.instantiateClass(viewClass);
+	}
+
 	/**
 	 * Creates a new View instance of the specified view class and configures it.
 	 * <p>Does <i>not</i> perform any lookup for pre-defined View instances.
@@ -277,10 +295,7 @@ public class UrlBasedViewResolver extends ViewResolverSupport
 	 * @see #applyLifecycleMethods
 	 */
 	protected AbstractUrlBasedView createView(String viewName) {
-		Class<?> viewClass = getViewClass();
-		Assert.state(viewClass != null, "No view class");
-
-		AbstractUrlBasedView view = (AbstractUrlBasedView) BeanUtils.instantiateClass(viewClass);
+		AbstractUrlBasedView view = instantiateView();
 		view.setSupportedMediaTypes(getSupportedMediaTypes());
 		view.setDefaultCharset(getDefaultCharset());
 		view.setUrl(getPrefix() + viewName + getSuffix());

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/freemarker/FreeMarkerViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.result.view.freemarker;
 
+import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
 import org.springframework.web.reactive.result.view.UrlBasedViewResolver;
 
 /**
@@ -57,4 +58,9 @@ public class FreeMarkerViewResolver extends UrlBasedViewResolver {
 		return FreeMarkerView.class;
 	}
 
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == FreeMarkerView.class ? new FreeMarkerView() : super.instantiateView());
+	}
+
 }

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/script/ScriptTemplateViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.result.view.script;
 
+import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
 import org.springframework.web.reactive.result.view.UrlBasedViewResolver;
 
 /**
@@ -61,4 +62,9 @@ public class ScriptTemplateViewResolver extends UrlBasedViewResolver {
 		return ScriptTemplateView.class;
 	}
 
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == ScriptTemplateView.class ? new ScriptTemplateView() : super.instantiateView());
+	}
+
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/view/InternalResourceViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -82,14 +82,6 @@ public class InternalResourceViewResolver extends UrlBasedViewResolver {
 	}
 
 
-	/**
-	 * This resolver requires {@link InternalResourceView}.
-	 */
-	@Override
-	protected Class<?> requiredViewClass() {
-		return InternalResourceView.class;
-	}
-
 	/**
 	 * Specify whether to always include the view rather than forward to it.
 	 * <p>Default is "false". Switch this flag on to enforce the use of a
@@ -101,6 +93,17 @@ public class InternalResourceViewResolver extends UrlBasedViewResolver {
 	}
 
 
+	@Override
+	protected Class<?> requiredViewClass() {
+		return InternalResourceView.class;
+	}
+
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == InternalResourceView.class ? new InternalResourceView() :
+				(getViewClass() == JstlView.class ? new JstlView() : super.instantiateView()));
+	}
+
 	@Override
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
 		InternalResourceView view = (InternalResourceView) super.buildView(viewName);

spring-webmvc/src/main/java/org/springframework/web/servlet/view/UrlBasedViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -144,8 +144,10 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 
 	/**
 	 * Set the view class that should be used to create views.
-	 * @param viewClass class that is assignable to the required view class
-	 * (by default, AbstractUrlBasedView)
+	 * @param viewClass a class that is assignable to the required view class
+	 * (by default: AbstractUrlBasedView)
+	 * @see #requiredViewClass()
+	 * @see #instantiateView()
 	 * @see AbstractUrlBasedView
 	 */
 	public void setViewClass(@Nullable Class<?> viewClass) {
@@ -158,21 +160,13 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 
 	/**
 	 * Return the view class to be used to create views.
+	 * @see #setViewClass
 	 */
 	@Nullable
 	protected Class<?> getViewClass() {
 		return this.viewClass;
 	}
 
-	/**
-	 * Return the required type of view for this resolver.
-	 * This implementation returns AbstractUrlBasedView.
-	 * @see AbstractUrlBasedView
-	 */
-	protected Class<?> requiredViewClass() {
-		return AbstractUrlBasedView.class;
-	}
-
 	/**
 	 * Set the prefix that gets prepended to view names when building a URL.
 	 */
@@ -510,6 +504,29 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		return (viewNames == null || PatternMatchUtils.simpleMatch(viewNames, viewName));
 	}
 
+	/**
+	 * Return the required type of view for this resolver.
+	 * This implementation returns {@link AbstractUrlBasedView}.
+	 * @see #instantiateView()
+	 * @see AbstractUrlBasedView
+	 */
+	protected Class<?> requiredViewClass() {
+		return AbstractUrlBasedView.class;
+	}
+
+	/**
+	 * Instantiate the specified view class.
+	 * <p>The default implementation uses reflection to instantiate the class.
+	 * @return a new instance of the view class
+	 * @since 5.3
+	 * @see #setViewClass
+	 */
+	protected AbstractUrlBasedView instantiateView() {
+		Class<?> viewClass = getViewClass();
+		Assert.state(viewClass != null, "No view class");
+		return (AbstractUrlBasedView) BeanUtils.instantiateClass(viewClass);
+	}
+
 	/**
 	 * Delegates to {@code buildView} for creating a new instance of the
 	 * specified view class. Applies the following Spring lifecycle methods
@@ -547,10 +564,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * @see #loadView(String, java.util.Locale)
 	 */
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
-		Class<?> viewClass = getViewClass();
-		Assert.state(viewClass != null, "No view class");
-
-		AbstractUrlBasedView view = (AbstractUrlBasedView) BeanUtils.instantiateClass(viewClass);
+		AbstractUrlBasedView view = instantiateView();
 		view.setUrl(getPrefix() + viewName + getSuffix());
 		view.setAttributesMap(getAttributesMap());
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/freemarker/FreeMarkerViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.view.freemarker;
 
 import org.springframework.web.servlet.view.AbstractTemplateViewResolver;
+import org.springframework.web.servlet.view.AbstractUrlBasedView;
 
 /**
  * Convenience subclass of {@link org.springframework.web.servlet.view.UrlBasedViewResolver}
@@ -70,4 +71,9 @@ public class FreeMarkerViewResolver extends AbstractTemplateViewResolver {
 		return FreeMarkerView.class;
 	}
 
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == FreeMarkerView.class ? new FreeMarkerView() : super.instantiateView());
+	}
+
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/view/groovy/GroovyMarkupViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -19,6 +19,7 @@ package org.springframework.web.servlet.view.groovy;
 import java.util.Locale;
 
 import org.springframework.web.servlet.view.AbstractTemplateViewResolver;
+import org.springframework.web.servlet.view.AbstractUrlBasedView;
 
 /**
  * Convenience subclass of @link AbstractTemplateViewResolver} that supports
@@ -65,6 +66,11 @@ public class GroovyMarkupViewResolver extends AbstractTemplateViewResolver {
 		return GroovyMarkupView.class;
 	}
 
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == GroovyMarkupView.class ? new GroovyMarkupView() : super.instantiateView());
+	}
+
 	/**
 	 * This resolver supports i18n, so cache keys should contain the locale.
 	 */

spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.servlet.view.script;
 
+import org.springframework.web.servlet.view.AbstractUrlBasedView;
 import org.springframework.web.servlet.view.UrlBasedViewResolver;
 
 /**
@@ -62,4 +63,9 @@ public class ScriptTemplateViewResolver extends UrlBasedViewResolver {
 		return ScriptTemplateView.class;
 	}
 
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == ScriptTemplateView.class ? new ScriptTemplateView() : super.instantiateView());
+	}
+
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/view/tiles3/TilesViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -19,6 +19,7 @@ package org.springframework.web.servlet.view.tiles3;
 import org.apache.tiles.request.render.Renderer;
 
 import org.springframework.lang.Nullable;
+import org.springframework.web.servlet.view.AbstractUrlBasedView;
 import org.springframework.web.servlet.view.UrlBasedViewResolver;
 
 /**
@@ -40,19 +41,14 @@ public class TilesViewResolver extends UrlBasedViewResolver {
 	private Boolean alwaysInclude;
 
 
-	public TilesViewResolver() {
-		setViewClass(requiredViewClass());
-	}
-
-
 	/**
 	 * This resolver requires {@link TilesView}.
 	 */
-	@Override
-	protected Class<?> requiredViewClass() {
-		return TilesView.class;
+	public TilesViewResolver() {
+		setViewClass(requiredViewClass());
 	}
 
+
 	/**
 	 * Set the {@link Renderer} to use. If not specified, a default
 	 * {@link org.apache.tiles.renderer.DefinitionRenderer} will be used.
@@ -74,6 +70,16 @@ public class TilesViewResolver extends UrlBasedViewResolver {
 	}
 
 
+	@Override
+	protected Class<?> requiredViewClass() {
+		return TilesView.class;
+	}
+
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == TilesView.class ? new TilesView() : super.instantiateView());
+	}
+
 	@Override
 	protected TilesView buildView(String viewName) throws Exception {
 		TilesView view = (TilesView) super.buildView(viewName);

spring-webmvc/src/main/java/org/springframework/web/servlet/view/xslt/XsltViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -53,16 +53,14 @@ public class XsltViewResolver extends UrlBasedViewResolver {
 	private boolean cacheTemplates = true;
 
 
+	/**
+	 * This resolver requires {@link XsltView}.
+	 */
 	public XsltViewResolver() {
 		setViewClass(requiredViewClass());
 	}
 
 
-	@Override
-	protected Class<?> requiredViewClass() {
-		return XsltView.class;
-	}
-
 	/**
 	 * Set the name of the model attribute that represents the XSLT Source.
 	 * If not specified, the model map will be searched for a matching value type.
@@ -127,6 +125,16 @@ public class XsltViewResolver extends UrlBasedViewResolver {
 	}
 
 
+	@Override
+	protected Class<?> requiredViewClass() {
+		return XsltView.class;
+	}
+
+	@Override
+	protected AbstractUrlBasedView instantiateView() {
+		return (getViewClass() == XsltView.class ? new XsltView() : super.instantiateView());
+	}
+
 	@Override
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
 		XsltView view = (XsltView) super.buildView(viewName);