Merge pull request #48347 from ddongjunn

* pr/48347:
  Polish "Use Charset instead of String for Mustache templates support"
  Use Charset instead of String for Mustache templates support

Closes gh-48347

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

@@ -78,7 +78,7 @@ public final class MustacheAutoConfiguration {
 	MustacheResourceTemplateLoader mustacheTemplateLoader() {
 		MustacheResourceTemplateLoader loader = new MustacheResourceTemplateLoader(this.mustache.getPrefix(),
 				this.mustache.getSuffix());
-		loader.setCharset(this.mustache.getCharsetName());
+		loader.setCharset(this.mustache.getCharset());
 		return loader;
 	}
 

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

@@ -124,6 +124,12 @@ public class MustacheProperties {
 		return this.charset;
 	}
 
+	/**
+	 * Return name of the charset.
+	 * @return the charset name
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of {@link #getCharset()}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
 	public String getCharsetName() {
 		return this.charset.name();
 	}

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

@@ -40,7 +40,7 @@ class MustacheReactiveWebConfiguration {
 		map.from(mustache::getSuffix).to(resolver::setSuffix);
 		map.from(mustache::getViewNames).to(resolver::setViewNames);
 		map.from(mustache::getRequestContextAttribute).to(resolver::setRequestContextAttribute);
-		map.from(mustache::getCharsetName).to(resolver::setCharset);
+		map.from(mustache::getCharset).to(resolver::setCharset);
 		map.from(mustache.getReactive()::getMediaTypes).to(resolver::setSupportedMediaTypes);
 		resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
 		return resolver;

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

@@ -18,6 +18,8 @@ package org.springframework.boot.mustache.autoconfigure;
 
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
@@ -45,7 +47,7 @@ public class MustacheResourceTemplateLoader implements TemplateLoader, ResourceL
 
 	private String suffix = "";
 
-	private String charSet = "UTF-8";
+	private Charset charset = StandardCharsets.UTF_8;
 
 	private ResourceLoader resourceLoader = new DefaultResourceLoader(null);
 
@@ -58,11 +60,23 @@ public class MustacheResourceTemplateLoader implements TemplateLoader, ResourceL
 	}
 
 	/**
-	 * Set the charset.
-	 * @param charSet the charset
+	 * Set the {@link Charset} to use.
+	 * @param charset the charset
+	 * @since 4.1.0
 	 */
-	public void setCharset(String charSet) {
-		this.charSet = charSet;
+	public void setCharset(Charset charset) {
+		this.charset = charset;
+	}
+
+	/**
+	 * Set the name of the charset to use.
+	 * @param charset the charset
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of
+	 * {@link #setCharset(Charset)}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
+	public void setCharset(String charset) {
+		this.charset = Charset.forName(charset);
 	}
 
 	/**
@@ -77,7 +91,7 @@ public class MustacheResourceTemplateLoader implements TemplateLoader, ResourceL
 	@Override
 	public Reader getTemplate(String name) throws Exception {
 		return new InputStreamReader(this.resourceLoader.getResource(this.prefix + name + this.suffix).getInputStream(),
-				this.charSet);
+				this.charset);
 	}
 
 }

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

@@ -49,7 +49,7 @@ class MustacheServletWebConfiguration {
 		resolver.setExposeSessionAttributes(mustache.getServlet().isExposeSessionAttributes());
 		resolver.setExposeSpringMacroHelpers(mustache.getServlet().isExposeSpringMacroHelpers());
 		resolver.setRequestContextAttribute(mustache.getRequestContextAttribute());
-		resolver.setCharset(mustache.getCharsetName());
+		resolver.setCharset(mustache.getCharset());
 		resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
 		return resolver;
 	}

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/reactive/view/MustacheView.java

@@ -53,7 +53,7 @@ public class MustacheView extends AbstractUrlBasedView {
 
 	private @Nullable Compiler compiler;
 
-	private @Nullable String charset;
+	private @Nullable Charset charset;
 
 	/**
 	 * Set the JMustache compiler to be used by this view. Typically this property is not
@@ -66,13 +66,25 @@ public class MustacheView extends AbstractUrlBasedView {
 	}
 
 	/**
-	 * Set the charset used for reading Mustache template files.
-	 * @param charset the charset to use for reading template files
+	 * Set the {@link Charset} used for reading Mustache template files.
+	 * @param charset the charset
+	 * @since 4.1.0
 	 */
-	public void setCharset(@Nullable String charset) {
+	public void setCharset(@Nullable Charset charset) {
 		this.charset = charset;
 	}
 
+	/**
+	 * Set the name of the charset used for reading Mustache template files.
+	 * @param charset the charset
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of
+	 * {@link #setCharset(Charset)}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
+	public void setCharset(@Nullable String charset) {
+		setCharset((charset != null) ? Charset.forName(charset) : null);
+	}
+
 	@Override
 	public boolean checkResourceExists(Locale locale) throws Exception {
 		return resolveResource() != null;

module/spring-boot-mustache/src/main/java/org/springframework/boot/mustache/reactive/view/MustacheViewResolver.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.mustache.reactive.view;
 
+import java.nio.charset.Charset;
+
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
 import org.jspecify.annotations.Nullable;
@@ -35,7 +37,7 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 
 	private final Compiler compiler;
 
-	private @Nullable String charset;
+	private @Nullable Charset charset;
 
 	/**
 	 * Create a {@code MustacheViewResolver} backed by a default instance of a
@@ -57,13 +59,25 @@ public class MustacheViewResolver extends UrlBasedViewResolver {
 	}
 
 	/**
-	 * Set the charset.
+	 * Set the {@link Charset} to use.
 	 * @param charset the charset
+	 * @since 4.1.0
 	 */
-	public void setCharset(String charset) {
+	public void setCharset(@Nullable Charset charset) {
 		this.charset = charset;
 	}
 
+	/**
+	 * Set the name of the charset to use.
+	 * @param charset the charset
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of
+	 * {@link #setCharset(Charset)}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
+	public void setCharset(@Nullable String charset) {
+		setCharset((charset != null) ? Charset.forName(charset) : null);
+	}
+
 	@Override
 	protected Class<?> requiredViewClass() {
 		return MustacheView.class;

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

@@ -19,6 +19,7 @@ package org.springframework.boot.mustache.servlet.view;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.nio.charset.Charset;
 import java.util.Locale;
 import java.util.Map;
 
@@ -46,7 +47,7 @@ public class MustacheView extends AbstractTemplateView {
 
 	private @Nullable Compiler compiler;
 
-	private @Nullable String charset;
+	private @Nullable Charset charset;
 
 	/**
 	 * Set the Mustache compiler to be used by this view.
@@ -61,13 +62,25 @@ public class MustacheView extends AbstractTemplateView {
 	}
 
 	/**
-	 * Set the charset used for reading Mustache template files.
-	 * @param charset the charset to use for reading template files
+	 * Set the {@link Charset} used for reading Mustache template files.
+	 * @param charset the charset
+	 * @since 4.1.0
 	 */
-	public void setCharset(@Nullable String charset) {
+	public void setCharset(@Nullable Charset charset) {
 		this.charset = charset;
 	}
 
+	/**
+	 * Set the name of the charset used for reading Mustache template files.
+	 * @param charset the charset
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of
+	 * {@link #setCharset(Charset)}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
+	public void setCharset(@Nullable String charset) {
+		setCharset((charset != null) ? Charset.forName(charset) : null);
+	}
+
 	@Override
 	public boolean checkResource(Locale locale) throws Exception {
 		Resource resource = getResource();

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.mustache.servlet.view;
 
+import java.nio.charset.Charset;
+
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
 import org.jspecify.annotations.Nullable;
@@ -34,7 +36,7 @@ public class MustacheViewResolver extends AbstractTemplateViewResolver {
 
 	private final Mustache.Compiler compiler;
 
-	private @Nullable String charset;
+	private @Nullable Charset charset;
 
 	/**
 	 * Create a {@code MustacheViewResolver} backed by a default instance of a
@@ -61,13 +63,25 @@ public class MustacheViewResolver extends AbstractTemplateViewResolver {
 	}
 
 	/**
-	 * Set the charset.
+	 * Set the {@link Charset} to use.
 	 * @param charset the charset
+	 * @since 4.1.0
 	 */
-	public void setCharset(@Nullable String charset) {
+	public void setCharset(@Nullable Charset charset) {
 		this.charset = charset;
 	}
 
+	/**
+	 * Set the name of the charset to use.
+	 * @param charset the charset
+	 * @deprecated since 4.1.0 for removal in 4.3.0 in favor of
+	 * {@link #setCharset(Charset)}
+	 */
+	@Deprecated(since = "4.1.0", forRemoval = true)
+	public void setCharset(@Nullable String charset) {
+		setCharset((charset != null) ? Charset.forName(charset) : null);
+	}
+
 	@Override
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
 		MustacheView view = (MustacheView) super.buildView(viewName);

module/spring-boot-mustache/src/test/java/org/springframework/boot/mustache/autoconfigure/MustacheAutoConfigurationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.mustache.autoconfigure;
 
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.function.Supplier;
 
@@ -96,7 +97,7 @@ class MustacheAutoConfigurationTests {
 			assertThat(viewResolver).extracting("allowRequestOverride", InstanceOfAssertFactories.BOOLEAN).isFalse();
 			assertThat(viewResolver).extracting("allowSessionOverride", InstanceOfAssertFactories.BOOLEAN).isFalse();
 			assertThat(viewResolver).extracting("cache", InstanceOfAssertFactories.BOOLEAN).isFalse();
-			assertThat(viewResolver).extracting("charset").isEqualTo("UTF-8");
+			assertThat(viewResolver).extracting("charset").isEqualTo(StandardCharsets.UTF_8);
 			assertThat(viewResolver).extracting("contentType").isEqualTo("text/html;charset=UTF-8");
 			assertThat(viewResolver).extracting("exposeRequestAttributes", InstanceOfAssertFactories.BOOLEAN).isFalse();
 			assertThat(viewResolver).extracting("exposeSessionAttributes", InstanceOfAssertFactories.BOOLEAN).isFalse();
@@ -112,7 +113,7 @@ class MustacheAutoConfigurationTests {
 		configure(new ReactiveWebApplicationContextRunner()).run((context) -> {
 			org.springframework.boot.mustache.reactive.view.MustacheViewResolver viewResolver = context
 				.getBean(org.springframework.boot.mustache.reactive.view.MustacheViewResolver.class);
-			assertThat(viewResolver).extracting("charset").isEqualTo("UTF-8");
+			assertThat(viewResolver).extracting("charset").isEqualTo(StandardCharsets.UTF_8);
 			assertThat(viewResolver).extracting("prefix").isEqualTo("classpath:/templates/");
 			assertThat(viewResolver).extracting("requestContextAttribute").isNull();
 			assertThat(viewResolver).extracting("suffix").isEqualTo(".mustache");
@@ -141,7 +142,7 @@ class MustacheAutoConfigurationTests {
 	@ParameterizedTest
 	@EnumSource
 	void charsetCanBeCustomizedOnViewResolver(ViewResolverKind kind) {
-		assertViewResolverProperty(kind, "spring.mustache.charset=UTF-16", "charset", "UTF-16");
+		assertViewResolverProperty(kind, "spring.mustache.charset=UTF-16", "charset", StandardCharsets.UTF_16);
 		if (kind == ViewResolverKind.SERVLET) {
 			assertViewResolverProperty(kind, "spring.mustache.charset=UTF-16", "contentType",
 					"text/html;charset=UTF-16");

module/spring-boot-mustache/src/test/java/org/springframework/boot/mustache/reactive/view/MustacheViewTests.java

@@ -47,7 +47,7 @@ class MustacheViewTests {
 		MustacheView view = new MustacheView();
 		view.setCompiler(Mustache.compiler());
 		view.setUrl("classpath:template.html");
-		view.setCharset(StandardCharsets.UTF_8.displayName());
+		view.setCharset(StandardCharsets.UTF_8);
 		view.setApplicationContext(this.context);
 		view.render(Collections.singletonMap("World", "Spring"), MediaType.TEXT_HTML, exchange)
 			.block(Duration.ofSeconds(30));