Java tutorial
/* * Copyright (C) 2012 Facebook, Inc. * * 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.facebook.swift.generator.util; import com.google.common.base.Charsets; import com.google.common.io.InputSupplier; import com.google.common.io.Resources; import org.antlr.stringtemplate.StringTemplate; import org.antlr.stringtemplate.StringTemplateErrorListener; import org.antlr.stringtemplate.StringTemplateGroup; import org.antlr.stringtemplate.language.AngleBracketTemplateLexer; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; public class TemplateLoader { private static final Logger LOG = LoggerFactory.getLogger(TemplateLoader.class); private final StringTemplateErrorListener ERROR_LISTENER = new LoaderErrorListener(); private final String templateFileName; private volatile StringTemplateGroup stg = null; public TemplateLoader(final String templateFileName) { this.templateFileName = templateFileName; } public StringTemplate load(final String templateName) throws IOException { final StringTemplateGroup stg = getTemplateGroup(); return stg.getInstanceOf(templateName); } protected StringTemplateGroup getTemplateGroup() throws IOException { if (stg == null) { final URL resourceUrl = Resources.getResource(this.getClass(), "/templates/" + templateFileName); final InputSupplier<InputStreamReader> is = Resources.newReaderSupplier(resourceUrl, Charsets.UTF_8); stg = new StringTemplateGroup(is.getInput(), AngleBracketTemplateLexer.class, ERROR_LISTENER); } return stg; } private static class LoaderErrorListener implements StringTemplateErrorListener { @Override public void error(String arg0, Throwable arg1) { LOG.error(String.format("%s: %s", arg0, arg1)); } @Override public void warning(String arg0) { LOG.warn(arg0); } } }