Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.kylin.common.util; import java.io.StringWriter; import java.io.Writer; import java.util.Map; import org.apache.commons.lang.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import freemarker.template.Configuration; import freemarker.template.Template; /** * Use a key to find a template for email. * * The template file is [KEY].ftl file under /mail_templates directory with classloader. */ public class MailTemplateProvider { private static final Logger logger = LoggerFactory.getLogger(MailTemplateProvider.class); private static MailTemplateProvider DEFAULT_INSTANCE = new MailTemplateProvider(); public static MailTemplateProvider getInstance() { return DEFAULT_INSTANCE; } private final Configuration configuration; private MailTemplateProvider() { configuration = new Configuration(Configuration.getVersion()); configuration.setClassForTemplateLoading(MailTemplateProvider.class, "/mail_templates"); configuration.setDefaultEncoding("UTF-8"); } public String buildMailContent(String tplKey, Map<String, Object> data) { try { Template template = getTemplate(tplKey); if (template == null) { return "Cannot find email template for " + tplKey; } try (Writer out = new StringWriter()) { template.process(data, out); return out.toString(); } } catch (Throwable e) { return e.getLocalizedMessage(); } } private Template getTemplate(String tplKey) throws Throwable { if (StringUtils.isEmpty(tplKey)) { return null; } return configuration.getTemplate(tplKey + ".ftl"); } }