Add spring-webflux compatibility to handlebars-springmvc (#642)

handlebars-springmvc/pom.xml

@@ -26,6 +26,16 @@
       <artifactId>spring-webmvc</artifactId>
     </dependency>
 
+    <dependency>
+      <groupId>org.springframework</groupId>
+      <artifactId>spring-webflux</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.apache.commons</groupId>
+      <artifactId>commons-lang3</artifactId>
+    </dependency>
+
     <!-- Servlet API -->
     <dependency>
       <groupId>javax.servlet</groupId>

handlebars-springmvc/src/main/java/com/github/jknack/handlebars/springmvc/HandlebarsViewResolver.java

@@ -17,6 +17,7 @@
  */
 package com.github.jknack.handlebars.springmvc;
 
+import static com.github.jknack.handlebars.springmvc.SpringUtils.createI18nSource;
 import static java.util.Objects.requireNonNull;
 
 import java.io.File;
@@ -26,10 +27,7 @@
 import java.net.URI;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.Enumeration;
 import java.util.List;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.ResourceBundle;
@@ -264,33 +262,6 @@ public void afterPropertiesSet() {
     handlebars.setCharset(charset);
   }
 
-  /**
-   * Creates a new i18n source.
-   *
-   * @param context The application context.
-   * @return A new i18n source.
-   */
-  private static I18nSource createI18nSource(final ApplicationContext context) {
-    return new I18nSource() {
-      @Override
-      public String message(final String key, final Locale locale, final Object... args) {
-        return context.getMessage(key, args, locale);
-      }
-
-      @Override
-      public String[] keys(final String basename, final Locale locale) {
-        ResourceBundle bundle = ResourceBundle.getBundle(basename, locale);
-        Enumeration<String> keys = bundle.getKeys();
-        List<String> result = new ArrayList<String>();
-        while (keys.hasMoreElements()) {
-          String key = keys.nextElement();
-          result.add(key);
-        }
-        return result.toArray(new String[result.size()]);
-      }
-    };
-  }
-
   /**
    * Creates a new {@link Handlebars} object using the parameter {@link TemplateLoader}.
    *

handlebars-springmvc/src/main/java/com/github/jknack/handlebars/springmvc/SpringUtils.java

@@ -0,0 +1,64 @@
+/**
+ * Copyright (c) 2012-2015 Edgar Espina
+ *
+ * This file is part of Handlebars.java.
+ *
+ * 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 com.github.jknack.handlebars.springmvc;
+
+import java.util.ArrayList;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.Locale;
+import java.util.ResourceBundle;
+
+import org.springframework.context.ApplicationContext;
+
+import com.github.jknack.handlebars.helper.I18nSource;
+
+/**
+ * @author OhChang Kwon([email protected])
+ */
+public final class SpringUtils {
+  /** private constructor for Util class. */
+  private SpringUtils() {
+  }
+
+  /**
+   * Creates a new i18n source.
+   *
+   * @param context The application context.
+   * @return A new i18n source.
+   */
+  public static I18nSource createI18nSource(final ApplicationContext context) {
+    return new I18nSource() {
+      @Override
+      public String message(final String key, final Locale locale, final Object... args) {
+        return context.getMessage(key, args, locale);
+      }
+
+      @Override
+      public String[] keys(final String basename, final Locale locale) {
+        ResourceBundle bundle = ResourceBundle.getBundle(basename, locale);
+        Enumeration<String> keys = bundle.getKeys();
+        List<String> result = new ArrayList<>();
+        while (keys.hasMoreElements()) {
+          String key = keys.nextElement();
+          result.add(key);
+        }
+        return result.toArray(new String[0]);
+      }
+    };
+  }
+}

handlebars-springmvc/src/main/java/com/github/jknack/handlebars/springmvc/webflux/ReactiveHandlebarsView.java

@@ -0,0 +1,127 @@
+/**
+ * Copyright (c) 2012-2015 Edgar Espina
+ *
+ * This file is part of Handlebars.java.
+ *
+ * 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 com.github.jknack.handlebars.springmvc.webflux;
+
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.Charset;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.http.MediaType;
+import org.springframework.util.MimeType;
+import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
+import org.springframework.web.server.ServerWebExchange;
+
+import com.github.jknack.handlebars.Context;
+import com.github.jknack.handlebars.Template;
+import com.github.jknack.handlebars.ValueResolver;
+
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+/**
+ * A handlebars reactive view implementation.
+ *
+ * @author OhChang Kwon([email protected])
+ */
+public class ReactiveHandlebarsView extends AbstractUrlBasedView {
+
+  /**
+   * The compiled template.
+   */
+  private Template template;
+
+  /**
+   * The value's resolvers.
+   */
+  private ValueResolver[] valueResolvers;
+
+  /**
+   * Set the value resolvers.
+   *
+   * @param valueResolvers The value resolvers. Required.
+   * @throws IllegalArgumentException If the value resolvers are null or empty.
+   */
+  void setValueResolvers(final ValueResolver... valueResolvers) {
+    if (ArrayUtils.isEmpty(valueResolvers)) {
+      throw new IllegalArgumentException("At least one value-resolver must be present.");
+    } else {
+      this.valueResolvers = valueResolvers;
+    }
+  }
+
+  /**
+   * @return The underlying template for this view.
+   */
+  public Template getTemplate() {
+    return this.template;
+  }
+
+  /**
+   * Set the compiled template.
+   *
+   * @param template The compiled template. Required.
+   */
+  void setTemplate(final Template template) {
+    this.template = Objects.requireNonNull(template,
+        "A handlebars template is required.");
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean checkResourceExists(final Locale locale) {
+    return template != null;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  protected Mono<Void> renderInternal(final Map<String, Object> renderAttributes,
+                                      final MediaType contentType,
+                                      final ServerWebExchange exchange) {
+    final Context context = Context.newBuilder(renderAttributes)
+        .resolver(valueResolvers)
+        .build();
+
+    final DataBuffer dataBuffer = exchange.getResponse().bufferFactory().allocateBuffer();
+    final Charset charset = Optional.ofNullable(contentType).map(MimeType::getCharset)
+        .orElse(getDefaultCharset());
+
+    try (final Writer writer = new OutputStreamWriter(dataBuffer.asOutputStream(), charset)) {
+      template.apply(context, writer);
+      writer.flush();
+    } catch (IOException e) {
+      DataBufferUtils.release(dataBuffer);
+      return Mono.error(e);
+    } finally {
+      context.destroy();
+    }
+
+    return exchange.getResponse().writeWith(Flux.just(dataBuffer));
+  }
+}