Refactor Mustache views support in Spring MVC

This commit simplifies the Mustache support for Spring MVC and removes
the included (view-based) i18n support in favor of more idiomatic
constructs like Mustache lambdas.

Fixes gh-8941

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mustache/MustacheAutoConfiguration.java

@@ -114,10 +114,9 @@ public class MustacheAutoConfiguration {
 		@Bean
 		@ConditionalOnMissingBean(MustacheViewResolver.class)
 		public MustacheViewResolver mustacheViewResolver(Compiler mustacheCompiler) {
-			MustacheViewResolver resolver = new MustacheViewResolver();
+			MustacheViewResolver resolver = new MustacheViewResolver(mustacheCompiler);
 			this.mustache.applyToViewResolver(resolver);
 			resolver.setCharset(this.mustache.getCharsetName());
-			resolver.setCompiler(mustacheCompiler);
 			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
 			return resolver;
 		}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mustache/servlet/MustacheView.java

@@ -16,58 +16,84 @@
 
 package org.springframework.boot.autoconfigure.mustache.servlet;
 
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.util.Locale;
 import java.util.Map;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Template;
 
+import org.springframework.core.io.Resource;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.view.AbstractTemplateView;
 
 /**
  * Spring MVC {@link View} using the Mustache template engine.
  *
+ * @author Brian Clozel
  * @author Dave Syer
  * @author Phillip Webb
- * @since 1.2.2
+ * @since 2.0.0
  */
 public class MustacheView extends AbstractTemplateView {
 
-	private Template template;
+	private Mustache.Compiler compiler;
+
+	private String charset;
 
 	/**
-	 * Create a new {@link MustacheView} instance.
+	 * Set the Mustache compiler to be used by this view.
-	 * @since 1.2.5
+	 * <p>Typically this property is not set directly. Instead a single
-	 * @see #setTemplate(Template)
+	 * {@link Mustache.Compiler} is expected in the Spring application context
+	 * which is used to compile Mustache templates.
+	 * @param compiler the Mustache compiler
 	 */
-	public MustacheView() {
+	public void setCompiler(Mustache.Compiler compiler) {
+		this.compiler = compiler;
 	}
 
 	/**
-	 * Create a new {@link MustacheView} with the specified template.
+	 * Set the charset used for reading Mustache template files.
-	 * @param template the source template
+	 * @param charset the charset to use for reading template files
 	 */
-	public MustacheView(Template template) {
+	public void setCharset(String charset) {
-		this.template = template;
+		this.charset = charset;
-	}
-
-	/**
-	 * Set the Mustache template that should actually be rendered.
-	 * @param template the mustache template
-	 * @since 1.2.5
-	 */
-	public void setTemplate(Template template) {
-		this.template = template;
 	}
 
 	@Override
-	protected void renderMergedTemplateModel(Map<String, Object> model,
+	public boolean checkResource(Locale locale) throws Exception {
-			HttpServletRequest request, HttpServletResponse response) throws Exception {
+		Resource resource = getApplicationContext().getResource(this.getUrl());
-		if (this.template != null) {
+		return (resource != null && resource.exists());
-			this.template.execute(model, response.getWriter());
+	}
+
+	@Override
+	protected void renderMergedTemplateModel(Map<String, Object> model, HttpServletRequest request,
+			HttpServletResponse response) throws Exception {
+		Template template = createTemplate(getApplicationContext().getResource(this.getUrl()));
+		if (template != null) {
+			template.execute(model, response.getWriter());
 		}
 	}
 
+	private Template createTemplate(Resource resource) throws IOException {
+		Reader reader = getReader(resource);
+		try {
+			return this.compiler.compile(reader);
+		}
+		finally {
+			reader.close();
+		}
+	}
+
+	private Reader getReader(Resource resource) throws IOException {
+		if (this.charset != null) {
+			return new InputStreamReader(resource.getInputStream(), this.charset);
+		}
+		return new InputStreamReader(resource.getInputStream());
+	}
 }

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mustache/servlet/MustacheViewResolver.java

@@ -16,36 +16,40 @@
 
 package org.springframework.boot.autoconfigure.mustache.servlet;
 
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.io.Reader;
-import java.util.Locale;
-
 import com.samskivert.mustache.Mustache;
-import com.samskivert.mustache.Mustache.Compiler;
-import com.samskivert.mustache.Template;
 
-import org.springframework.beans.propertyeditors.LocaleEditor;
-import org.springframework.core.io.Resource;
-import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.view.AbstractTemplateViewResolver;
+import org.springframework.web.servlet.view.AbstractUrlBasedView;
 
 /**
  * Spring MVC {@link ViewResolver} for Mustache.
  *
- * @author Dave Syer
+ * @author Brian Clozel
- * @author Andy Wilkinson
+ * @since 2.0.0
- * @author Phillip Webb
- * @since 1.2.2
  */
 public class MustacheViewResolver extends AbstractTemplateViewResolver {
 
-	private Compiler compiler = Mustache.compiler();
+	private final Mustache.Compiler compiler;
 
 	private String charset;
 
+	/**
+	 * Create a {@code MustacheViewResolver} backed by a default
+	 * instance of a {@link Mustache.Compiler}.
+	 */
 	public MustacheViewResolver() {
+		this.compiler = Mustache.compiler();
+		setViewClass(requiredViewClass());
+	}
+
+	/**
+	 * Create a {@code MustacheViewResolver} backed by a custom
+	 * instance of a {@link Mustache.Compiler}.
+	 * @param compiler the Mustache compiler used to compile templates
+	 */
+	public MustacheViewResolver(Mustache.Compiler compiler) {
+		this.compiler = compiler;
 		setViewClass(requiredViewClass());
 	}
 
@@ -54,14 +58,6 @@ public class MustacheViewResolver extends AbstractTemplateViewResolver {
 		return MustacheView.class;
 	}
 
-	/**
-	 * Set the compiler.
-	 * @param compiler the compiler
-	 */
-	public void setCompiler(Compiler compiler) {
-		this.compiler = compiler;
-	}
-
 	/**
 	 * Set the charset.
 	 * @param charset the charset
@@ -71,57 +67,11 @@ public class MustacheViewResolver extends AbstractTemplateViewResolver {
 	}
 
 	@Override
-	protected View loadView(String viewName, Locale locale) throws Exception {
+	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
-		Resource resource = resolveResource(viewName, locale);
+		MustacheView view = (MustacheView) super.buildView(viewName);
-		if (resource == null) {
+		view.setCompiler(this.compiler);
-			return null;
+		view.setCharset(this.charset);
-		}
+		return view;
-		MustacheView mustacheView = (MustacheView) super.loadView(viewName, locale);
-		mustacheView.setTemplate(createTemplate(resource));
-		return mustacheView;
-	}
-
-	private Resource resolveResource(String viewName, Locale locale) {
-		return resolveFromLocale(viewName, getLocale(locale));
-	}
-
-	private Resource resolveFromLocale(String viewName, String locale) {
-		Resource resource = getApplicationContext()
-				.getResource(getPrefix() + viewName + locale + getSuffix());
-		if (resource == null || !resource.exists()) {
-			if (locale.isEmpty()) {
-				return null;
-			}
-			int index = locale.lastIndexOf("_");
-			return resolveFromLocale(viewName, locale.substring(0, index));
-		}
-		return resource;
-	}
-
-	private String getLocale(Locale locale) {
-		if (locale == null) {
-			return "";
-		}
-		LocaleEditor localeEditor = new LocaleEditor();
-		localeEditor.setValue(locale);
-		return "_" + localeEditor.getAsText();
-	}
-
-	private Template createTemplate(Resource resource) throws IOException {
-		Reader reader = getReader(resource);
-		try {
-			return this.compiler.compile(reader);
-		}
-		finally {
-			reader.close();
-		}
-	}
-
-	private Reader getReader(Resource resource) throws IOException {
-		if (this.charset != null) {
-			return new InputStreamReader(resource.getInputStream(), this.charset);
-		}
-		return new InputStreamReader(resource.getInputStream());
 	}
 
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mustache/servlet/MustacheViewResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -16,23 +16,14 @@
 
 package org.springframework.boot.autoconfigure.mustache.servlet;
 
-import java.io.ByteArrayInputStream;
-import java.io.InputStream;
-import java.util.Locale;
-
 import org.junit.Before;
 import org.junit.Test;
 
-import org.springframework.core.io.Resource;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.mock.web.MockServletContext;
-import org.springframework.web.context.support.StaticWebApplicationContext;
 import org.springframework.web.servlet.View;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.mockito.BDDMockito.given;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link MustacheViewResolver}.
@@ -46,7 +37,9 @@ public class MustacheViewResolverTests {
 
 	@Before
 	public void init() {
-		this.resolver.setApplicationContext(new StaticWebApplicationContext());
+		GenericApplicationContext applicationContext = new GenericApplicationContext();
+		applicationContext.refresh();
+		this.resolver.setApplicationContext(applicationContext);
 		this.resolver.setServletContext(new MockServletContext());
 		this.resolver.setPrefix("classpath:/mustache-templates/");
 		this.resolver.setSuffix(".html");
@@ -58,32 +51,10 @@ public class MustacheViewResolverTests {
 	}
 
 	@Test
-	public void resolveNullLocale() throws Exception {
+	public void resolveExisting() throws Exception {
 		assertThat(this.resolver.resolveViewName("foo", null)).isNotNull();
 	}
 
-	@Test
-	public void resolveDefaultLocale() throws Exception {
-		assertThat(this.resolver.resolveViewName("foo", Locale.US)).isNotNull();
-	}
-
-	@Test
-	public void resolveDoubleLocale() throws Exception {
-		assertThat(this.resolver.resolveViewName("foo", Locale.CANADA_FRENCH))
-				.isNotNull();
-	}
-
-	@Test
-	public void resolveTripleLocale() throws Exception {
-		assertThat(this.resolver.resolveViewName("foo", new Locale("en", "GB", "cy")))
-				.isNotNull();
-	}
-
-	@Test
-	public void resolveSpecificLocale() throws Exception {
-		assertThat(this.resolver.resolveViewName("foo", new Locale("de"))).isNotNull();
-	}
-
 	@Test
 	public void setsContentType() throws Exception {
 		this.resolver.setContentType("application/octet-stream");
@@ -92,24 +63,4 @@ public class MustacheViewResolverTests {
 
 	}
 
-	@Test
-	public void templateResourceInputStreamIsClosed() throws Exception {
-		final Resource resource = mock(Resource.class);
-		given(resource.exists()).willReturn(true);
-		InputStream inputStream = new ByteArrayInputStream(new byte[0]);
-		InputStream spyInputStream = spy(inputStream);
-		given(resource.getInputStream()).willReturn(spyInputStream);
-		this.resolver = new MustacheViewResolver();
-		this.resolver.setApplicationContext(new StaticWebApplicationContext() {
-
-			@Override
-			public Resource getResource(String location) {
-				return resource;
-			}
-
-		});
-		this.resolver.loadView("foo", null);
-		verify(spyInputStream).close();
-	}
-
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mustache/servlet/MustacheViewTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -55,12 +55,12 @@ public class MustacheViewTests {
 
 	@Test
 	public void viewResolvesHandlebars() throws Exception {
-		MustacheView view = new MustacheView(
+		MustacheView view = new MustacheView();
-				Mustache.compiler().compile("Hello {{msg}}"));
+		view.setCompiler(Mustache.compiler());
+		view.setUrl("classpath:/mustache-templates/foo.html");
 		view.setApplicationContext(this.context);
-		view.render(Collections.singletonMap("msg", "World"), this.request,
+		view.render(Collections.singletonMap("World", "Spring"), this.request, this.response);
-				this.response);
+		assertThat(this.response.getContentAsString()).isEqualTo("Hello Spring");
-		assertThat(this.response.getContentAsString()).isEqualTo("Hello World");
 	}
 
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mustache/servlet/MustacheWebIntegrationTests.java

@@ -120,12 +120,12 @@ public class MustacheWebIntegrationTests {
 
 		@Bean
 		public MustacheViewResolver viewResolver() {
-			MustacheViewResolver resolver = new MustacheViewResolver();
+			Mustache.Compiler compiler = Mustache.compiler()
+					.withLoader(new MustacheResourceTemplateLoader("classpath:/mustache-templates/",
+							".html"));
+			MustacheViewResolver resolver = new MustacheViewResolver(compiler);
 			resolver.setPrefix("classpath:/mustache-templates/");
 			resolver.setSuffix(".html");
-			resolver.setCompiler(
-					Mustache.compiler().withLoader(new MustacheResourceTemplateLoader(
-							"classpath:/mustache-templates/", ".html")));
 			return resolver;
 		}