Review TemplateRenderer abstraction

Closes gh-818

initializr-generator/src/main/java/io/spring/initializr/generator/io/template/MustacheTemplateRenderer.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2012-2019 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.
+ * 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 io.spring.initializr.generator.io.template;
+
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import java.util.function.Function;
+
+import com.samskivert.mustache.Mustache;
+import com.samskivert.mustache.Mustache.Compiler;
+import com.samskivert.mustache.Mustache.TemplateLoader;
+import com.samskivert.mustache.Template;
+
+import org.springframework.cache.Cache;
+import org.springframework.cache.Cache.ValueRetrievalException;
+import org.springframework.core.io.DefaultResourceLoader;
+import org.springframework.core.io.ResourceLoader;
+
+/**
+ * A {@link TemplateRenderer} using Mustache.
+ *
+ * @author Stephane Nicoll
+ */
+public class MustacheTemplateRenderer implements TemplateRenderer {
+
+	private final Compiler mustache;
+
+	private final Function<String, String> keyGenerator;
+
+	private final Cache templateCache;
+
+	public MustacheTemplateRenderer(String resourcePrefix, Cache templateCache) {
+		String prefix = (resourcePrefix.endsWith("/") ? resourcePrefix
+				: resourcePrefix + "/");
+		this.mustache = Mustache.compiler().withLoader(mustacheTemplateLoader(prefix));
+		this.keyGenerator = (name) -> String.format("%s%s", prefix, name);
+		this.templateCache = templateCache;
+	}
+
+	public MustacheTemplateRenderer(String resourcePrefix) {
+		this(resourcePrefix, null);
+	}
+
+	private static TemplateLoader mustacheTemplateLoader(String prefix) {
+		ResourceLoader resourceLoader = new DefaultResourceLoader();
+		return (name) -> {
+			String location = prefix + name + ".mustache";
+			return new InputStreamReader(
+					resourceLoader.getResource(location).getInputStream(),
+					StandardCharsets.UTF_8);
+		};
+	}
+
+	@Override
+	public String render(String templateName, Map<String, ?> model) throws IOException {
+		Template template = getTemplate(templateName);
+		return template.execute(model);
+	}
+
+	private Template getTemplate(String name) {
+		try {
+			if (this.templateCache != null) {
+				try {
+					return this.templateCache.get(this.keyGenerator.apply(name),
+							() -> loadTemplate(name));
+				}
+				catch (ValueRetrievalException ex) {
+					throw ex.getCause();
+				}
+			}
+			return loadTemplate(name);
+		}
+		catch (Throwable ex) {
+			throw new IllegalStateException("Cannot load template " + name, ex);
+		}
+	}
+
+	private Template loadTemplate(String name) throws Exception {
+		Reader template = this.mustache.loader.getTemplate(name);
+		return this.mustache.compile(template);
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/io/template/TemplateRenderer.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2019 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.
+ * 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 io.spring.initializr.generator.io.template;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * Template rendering abstraction.
+ *
+ * @author Stephane Nicoll
+ */
+@FunctionalInterface
+public interface TemplateRenderer {
+
+	/**
+	 * Render the template with the specified name and the specified model.
+	 * @param templateName the name of the template
+	 * @param model the model to use
+	 * @return the rendering result
+	 * @throws IOException if rendering the template failed
+	 */
+	String render(String templateName, Map<String, ?> model) throws IOException;
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/io/template/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2019 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.
+ * 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.
+ */
+
+/**
+ * Template rendering abstraction.
+ */
+package io.spring.initializr.generator.io.template;

initializr-generator/src/main/java/io/spring/initializr/util/TemplateRenderer.java

@@ -1,108 +0,0 @@
-/*
- * Copyright 2012-2018 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.
- * 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 io.spring.initializr.util;
-
-import java.io.InputStreamReader;
-import java.io.Reader;
-import java.nio.charset.Charset;
-import java.util.Map;
-import java.util.concurrent.ConcurrentMap;
-
-import com.samskivert.mustache.Mustache;
-import com.samskivert.mustache.Mustache.Compiler;
-import com.samskivert.mustache.Mustache.TemplateLoader;
-import com.samskivert.mustache.Template;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import org.springframework.core.io.DefaultResourceLoader;
-import org.springframework.core.io.ResourceLoader;
-import org.springframework.util.ConcurrentReferenceHashMap;
-
-/**
- * A template renderer backed by Mustache.
- *
- * @author Dave Syer
- */
-public class TemplateRenderer {
-
-	private static final Logger log = LoggerFactory.getLogger(TemplateRenderer.class);
-
-	private boolean cache = true;
-
-	private final Compiler mustache;
-
-	private final ConcurrentMap<String, Template> templateCaches = new ConcurrentReferenceHashMap<>();
-
-	public TemplateRenderer() {
-		this(mustacheCompiler());
-	}
-
-	public TemplateRenderer(Compiler mustache) {
-		this.mustache = mustache;
-	}
-
-	public boolean isCache() {
-		return this.cache;
-	}
-
-	public void setCache(boolean cache) {
-		this.cache = cache;
-	}
-
-	public String process(String name, Map<String, ?> model) {
-		try {
-			Template template = getTemplate(name);
-			return template.execute(model);
-		}
-		catch (Exception ex) {
-			log.error("Cannot render: " + name, ex);
-			throw new IllegalStateException("Cannot render template", ex);
-		}
-	}
-
-	public Template getTemplate(String name) {
-		if (this.cache) {
-			return this.templateCaches.computeIfAbsent(name, this::loadTemplate);
-		}
-		return loadTemplate(name);
-	}
-
-	protected Template loadTemplate(String name) {
-		try {
-			Reader template;
-			template = this.mustache.loader.getTemplate(name);
-			return this.mustache.compile(template);
-		}
-		catch (Exception ex) {
-			throw new IllegalStateException("Cannot load template " + name, ex);
-		}
-	}
-
-	private static Compiler mustacheCompiler() {
-		return Mustache.compiler().withLoader(mustacheTemplateLoader());
-	}
-
-	private static TemplateLoader mustacheTemplateLoader() {
-		ResourceLoader resourceLoader = new DefaultResourceLoader();
-		String prefix = "classpath:/templates/";
-		Charset charset = Charset.forName("UTF-8");
-		return (name) -> new InputStreamReader(
-				resourceLoader.getResource(prefix + name).getInputStream(), charset);
-	}
-
-}

initializr-generator/src/test/java/io/spring/initializr/generator/io/template/MustacheTemplateRendererTests.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2019 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.
+ * 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 io.spring.initializr.generator.io.template;
+
+import java.io.IOException;
+import java.util.Collections;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.cache.Cache;
+import org.springframework.cache.concurrent.ConcurrentMapCache;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+/**
+ * Tests for {@link MustacheTemplateRenderer}.
+ *
+ * @author Stephane Nicoll
+ */
+class MustacheTemplateRendererTests {
+
+	private final Cache templatesCache = new ConcurrentMapCache("test");
+
+	@Test
+	void renderTemplate() throws IOException {
+		MustacheTemplateRenderer render = new MustacheTemplateRenderer(
+				"classpath:/templates/mustache", this.templatesCache);
+		assertThat(this.templatesCache.get("classpath:/templates/mustache/test"))
+				.isNull();
+		assertThat(render.render("test", Collections.singletonMap("key", "value")))
+				.isEqualTo("value");
+		assertThat(this.templatesCache.get("classpath:/templates/mustache/test"))
+				.isNotNull();
+	}
+
+	@Test
+	void renderTemplateWithoutCache() throws IOException {
+		MustacheTemplateRenderer render = new MustacheTemplateRenderer(
+				"classpath:/templates/mustache");
+		assertThat(render.render("test", Collections.singletonMap("key", "value")))
+				.isEqualTo("value");
+	}
+
+	@Test
+	void renderUnknownTemplate() {
+		MustacheTemplateRenderer render = new MustacheTemplateRenderer(
+				"classpath:/templates/mustache", this.templatesCache);
+		assertThatExceptionOfType(IllegalStateException.class)
+				.isThrownBy(() -> render.render("does-not-exist", Collections.emptyMap()))
+				.withMessageContaining("Cannot load template")
+				.withMessageContaining("does-not-exist");
+	}
+
+}

initializr-generator/src/test/resources/templates/mustache/test.mustache

@@ -0,0 +1 @@
+{{key}}