org.springframework.boot.web.reactive.result.view.MustacheView Maven / Gradle / Ivy
/*
* Copyright 2012-2023 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
*
* https://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 org.springframework.boot.web.reactive.result.view;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import com.samskivert.mustache.Mustache.Compiler;
import com.samskivert.mustache.Template;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.io.Resource;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.result.view.AbstractUrlBasedView;
import org.springframework.web.reactive.result.view.View;
import org.springframework.web.server.ServerWebExchange;
/**
* Spring WebFlux {@link View} using the Mustache template engine.
*
* @author Brian Clozel
* @since 2.0.0
*/
public class MustacheView extends AbstractUrlBasedView {
private Compiler compiler;
private String charset;
/**
* Set the JMustache compiler to be used by this view. Typically this property is not
* set directly. Instead a single {@link Compiler} is expected in the Spring
* application context which is used to compile Mustache templates.
* @param compiler the Mustache compiler
*/
public void setCompiler(Compiler compiler) {
this.compiler = compiler;
}
/**
* Set the charset used for reading Mustache template files.
* @param charset the charset to use for reading template files
*/
public void setCharset(String charset) {
this.charset = charset;
}
@Override
public boolean checkResourceExists(Locale locale) throws Exception {
return resolveResource() != null;
}
@Override
protected Mono renderInternal(Map model, MediaType contentType, ServerWebExchange exchange) {
Resource resource = resolveResource();
if (resource == null) {
return Mono
.error(new IllegalStateException("Could not find Mustache template with URL [" + getUrl() + "]"));
}
DataBuffer dataBuffer = exchange.getResponse().bufferFactory().allocateBuffer();
try (Reader reader = getReader(resource)) {
Template template = this.compiler.compile(reader);
Charset charset = getCharset(contentType).orElseGet(this::getDefaultCharset);
try (Writer writer = new OutputStreamWriter(dataBuffer.asOutputStream(), charset)) {
template.execute(model, writer);
writer.flush();
}
}
catch (Exception ex) {
DataBufferUtils.release(dataBuffer);
return Mono.error(ex);
}
return exchange.getResponse().writeWith(Flux.just(dataBuffer));
}
private Resource resolveResource() {
Resource resource = getApplicationContext().getResource(getUrl());
if (resource == null || !resource.exists()) {
return null;
}
return resource;
}
private Reader getReader(Resource resource) throws IOException {
if (this.charset != null) {
return new InputStreamReader(resource.getInputStream(), this.charset);
}
return new InputStreamReader(resource.getInputStream());
}
private Optional getCharset(MediaType mediaType) {
return Optional.ofNullable((mediaType != null) ? mediaType.getCharset() : null);
}
}