Use buildView() to create MustacheView

Update MustacheViewResolver so that buildView() is called to create
the MustacheView. This sets fields such as `contentType` and allows us
to remove explicit setApplicationContext() and setServletContext()
calls.

Fixes gh-3265

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

@@ -30,20 +30,44 @@ import com.samskivert.mustache.Template;
  * Spring MVC {@link View} using the Mustache template engine.
  *
  * @author Dave Syer
+ * @author Phillip Webb
  * @since 1.2.2
  */
 public class MustacheView extends AbstractTemplateView {
 
-	private final Template template;
+	private Template template;
 
+	/**
+	 * Create a new {@link MustacheView} instance.
+	 * @see #setTemplate(Template)
+	 * @since 1.2.5
+	 */
+	public MustacheView() {
+	}
+
+	/**
+	 * Create a new {@link MustacheView} with the specified template.
+	 * @param template the source template
+	 */
 	public MustacheView(Template template) {
 		this.template = template;
 	}
 
+	/**
+	 * 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,
 			HttpServletRequest request, HttpServletResponse response) throws Exception {
-		this.template.execute(model, response.getWriter());
+		if (this.template != null) {
+			this.template.execute(model, response.getWriter());
+		}
 	}
 
 }

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

@@ -18,6 +18,7 @@ package org.springframework.boot.autoconfigure.mustache.web;
 
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.Reader;
 import java.util.Locale;
 
 import org.springframework.beans.propertyeditors.LocaleEditor;
@@ -35,6 +36,7 @@ import com.samskivert.mustache.Template;
  *
  * @author Dave Syer
  * @author Andy Wilkinson
+ * @author Phillip Webb
  * @since 1.2.2
  */
 public class MustacheViewResolver extends UrlBasedViewResolver {
@@ -44,7 +46,12 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 	private String charset;
 
 	public MustacheViewResolver() {
-		setViewClass(MustacheView.class);
+		setViewClass(requiredViewClass());
+	}
+
+	@Override
+	protected Class<?> requiredViewClass() {
+		return MustacheView.class;
 	}
 
 	/**
@@ -67,31 +74,15 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 		if (resource == null) {
 			return null;
 		}
-		MustacheView view = new MustacheView(createTemplate(resource));
-		view.setApplicationContext(getApplicationContext());
-		view.setServletContext(getServletContext());
-		return view;
-	}
-
-	private Template createTemplate(Resource resource) throws IOException {
-		return this.charset == null ? this.compiler.compile(new InputStreamReader(
-				resource.getInputStream())) : this.compiler
-				.compile(new InputStreamReader(resource.getInputStream(), this.charset));
+		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 String getLocale(Locale locale) {
-		if (locale == null) {
-			return "";
-		}
-		LocaleEditor localeEditor = new LocaleEditor();
-		localeEditor.setValue(locale);
-		return "_" + localeEditor.getAsText();
-	}
-
 	private Resource resolveFromLocale(String viewName, String locale) {
 		Resource resource = getApplicationContext().getResource(
 				getPrefix() + viewName + locale + getSuffix());
@@ -105,4 +96,24 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 		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 {
+		return this.compiler.compile(getReader(resource));
+	}
+
+	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/web/MustacheViewResolverTests.java

@@ -20,12 +20,14 @@ import java.util.Locale;
 
 import org.junit.Before;
 import org.junit.Test;
-import org.springframework.boot.autoconfigure.mustache.web.MustacheViewResolver;
 import org.springframework.mock.web.MockServletContext;
 import org.springframework.web.context.support.StaticWebApplicationContext;
+import org.springframework.web.servlet.View;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
 
 /**
  * Tests for {@link MustacheViewResolver}.
@@ -74,4 +76,12 @@ public class MustacheViewResolverTests {
 		assertNotNull(this.resolver.resolveViewName("foo", new Locale("de")));
 	}
 
+	@Test
+	public void setsContentType() throws Exception {
+		this.resolver.setContentType("application/octet-stream");
+		View view = this.resolver.resolveViewName("foo", null);
+		assertThat(view.getContentType(), equalTo("application/octet-stream"));
+
+	}
+
 }