/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* 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.alibaba.citrus.service.freemarker.impl;
import static com.alibaba.citrus.service.freemarker.FreeMarkerConfiguration.*;
import static com.alibaba.citrus.util.StringUtil.*;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Locale;
import com.alibaba.citrus.service.AbstractService;
import com.alibaba.citrus.service.configuration.ProductionModeAware;
import com.alibaba.citrus.service.freemarker.FreeMarkerEngine;
import com.alibaba.citrus.service.template.TemplateContext;
import com.alibaba.citrus.service.template.TemplateException;
import com.alibaba.citrus.util.i18n.LocaleUtil;
import freemarker.core.Environment;
import freemarker.core.ParseException;
import freemarker.log.Logger;
import freemarker.template.Template;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.ResourceLoader;
/**
* FreeMarker模板引擎。
*
* @author Michael Zhou
*/
public class FreeMarkerEngineImpl extends AbstractService<FreeMarkerEngine>
implements FreeMarkerEngine, ResourceLoaderAware, ProductionModeAware {
private final FreeMarkerConfigurationImpl configuration = new FreeMarkerConfigurationImpl(getLogger());
// 初始化slf4j日志。
static {
try {
Logger.selectLoggerLibrary(Logger.LIBRARY_SLF4J);
Logger.setCategoryPrefix("");
} catch (Throwable ee) {
}
}
public FreeMarkerConfigurationImpl getConfiguration() {
return configuration;
}
public void setResourceLoader(ResourceLoader loader) {
configuration.setResourceLoader(loader);
}
public void setProductionMode(boolean productionMode) {
configuration.setProductionMode(productionMode);
}
/** 初始化engine。 */
@Override
protected void init() {
configuration.init();
getLogger().debug("FreeMarker Engine Configurations: {}", configuration);
}
/**
* 取得默认的模板名后缀列表。
* <p>
* 当<code>TemplateService</code>没有指定到当前engine的mapping时，将取得本方法所返回的后缀名列表。
* </p>
*/
public String[] getDefaultExtensions() {
return new String[] { "ftl" };
}
/** 判定模板是否存在。 */
public boolean exists(String templateName) {
try {
return configuration.getTemplateLoader().findTemplateSource(templateName) != null;
} catch (IOException e) {
return false;
}
}
/** 渲染模板，并以字符串的形式取得渲染的结果。 */
public String getText(String templateName, TemplateContext context) throws TemplateException, IOException {
StringWriter out = new StringWriter();
render(templateName, context, out, null, null, null);
return out.toString();
}
/** 渲染模板，并将渲染的结果送到字节输出流中。 */
public void writeTo(String templateName, TemplateContext context, OutputStream ostream) throws TemplateException,
IOException {
render(templateName, context, null, ostream, null, null);
}
/** 渲染模板，并将渲染的结果送到字符输出流中。 */
public void writeTo(String templateName, TemplateContext context, Writer writer) throws TemplateException,
IOException {
render(templateName, context, writer, null, null, null);
}
public String mergeTemplate(String templateName, Object context, String inputCharset) throws TemplateException,
IOException {
StringWriter out = new StringWriter();
render(templateName, context, out, null, inputCharset, null);
return out.toString();
}
public void mergeTemplate(String templateName, Object context, OutputStream ostream, String inputCharset,
String outputCharset) throws TemplateException, IOException {
render(templateName, context, null, ostream, inputCharset, outputCharset);
}
public void mergeTemplate(String templateName, Object context, Writer out, String inputCharset)
throws TemplateException, IOException {
render(templateName, context, out, null, inputCharset, null);
}
/** 渲染模板到指定输出流。 */
private void render(String templateName, Object context, Writer writer, OutputStream ostream, String inputCharset,
String outputCharset) throws TemplateException, IOException {
Locale locale = LocaleUtil.getContext().getLocale();
// inputCharset依次为：指定值、engine初始化时的默认值、DEFAULT_CHARSET
if (isEmpty(inputCharset)) {
inputCharset = configuration.getConfiguration().getDefaultEncoding();
}
inputCharset = defaultIfEmpty(inputCharset, DEFAULT_CHARSET);
// outputCharset依次为：指定值、engine初始化时的默认值、DEFAULT_CHARSET
if (isEmpty(outputCharset)) {
outputCharset = configuration.getConfiguration().getOutputEncoding();
}
outputCharset = defaultIfEmpty(outputCharset, DEFAULT_CHARSET);
if (writer == null) {
if (ostream == null) {
throw new IllegalArgumentException("missing output writer");
}
writer = new OutputStreamWriter(ostream, outputCharset);
}
try {
Template template = configuration.getConfiguration().getTemplate(templateName, locale, inputCharset);
Environment env = template.createProcessingEnvironment(context, writer);
env.setLocale(locale);
env.setOutputEncoding(outputCharset);
env.process();
} catch (freemarker.template.TemplateException e) {
error(templateName, e);
} catch (ParseException e) {
error(templateName, e);
}
}
private void error(String templateName, Throwable e) {
throw new TemplateException("Error rendering FreeMarker template: " + templateName, e);
}
}