Java tutorial
/* * BeanShell Web * Copyright (C) 2012 Stefano Fornari * * This program is free software; you can redistribute it and/or modify it under * the terms of the GNU Affero General Public License version 3 as published by * the Free Software Foundation with the addition of the following permission * added to Section 15 as permitted in Section 7(a): FOR ANY PART OF THE COVERED * WORK IN WHICH THE COPYRIGHT IS OWNED BY Stefano Fornari, Stefano Fornari * DISCLAIMS THE WARRANTY OF NON INFRINGEMENT OF THIRD PARTY RIGHTS. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more * details. * * You should have received a copy of the GNU Affero General Public License * along with this program; if not, see http://www.gnu.org/licenses or write to * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, * MA 02110-1301 USA. */ package ste.web.http.velocity; import java.io.ByteArrayInputStream; import java.io.File; import java.io.IOException; import java.io.OutputStreamWriter; import java.io.Writer; import java.net.URI; import java.net.URISyntaxException; import org.apache.commons.io.output.ByteArrayOutputStream; import org.apache.commons.lang.StringUtils; import org.apache.http.HttpException; import org.apache.http.HttpRequest; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.HttpVersion; import org.apache.http.entity.BasicHttpEntity; import org.apache.http.entity.ContentType; import org.apache.http.protocol.HttpContext; import org.apache.http.protocol.HttpRequestHandler; import org.apache.velocity.Template; import org.apache.velocity.VelocityContext; import org.apache.velocity.app.VelocityEngine; import org.apache.velocity.exception.MethodInvocationException; import org.apache.velocity.exception.ParseErrorException; import org.apache.velocity.exception.ResourceNotFoundException; import static ste.web.beanshell.Constants.*; import ste.web.http.HttpSessionContext; import ste.web.http.QueryString; /** * * @author ste */ public class VelocityHandler implements HttpRequestHandler { // --------------------------------------------------------------- Constants // ------------------------------------------------------------ Private data private VelocityEngine engine; private String viewsFolder; // ------------------------------------------------------------ Constructors public VelocityHandler(final String webroot) { if (webroot == null) { throw new IllegalArgumentException("webroot can not be null"); } engine = new VelocityEngine(); engine.setProperty("file.resource.loader.path", webroot); engine.setProperty("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.FileResourceLoader"); engine.setProperty("resource.loader", "file"); engine.init(); setViewsFolder(null); } public VelocityHandler(final String webroot, final String viewsFolder) { this(webroot); setViewsFolder(viewsFolder); } // ---------------------------------------------------------- Public methods /** * @return the viewsFolder * */ public String getViewsFolder() { return viewsFolder; } /** * Sets the folder where views are located. If the the given value is null, * it defaults to DEFAULT_VIEWS_PREFIX. * * @param viewsFolder the viewsFolder to set - NULL */ public void setViewsFolder(final String viewsFolder) { if (viewsFolder == null) { this.viewsFolder = DEFAULT_VIEWS_PREFIX; } else { // // let's fix a common mistake :) // this.viewsFolder = (!viewsFolder.startsWith("/")) ? ('/' + viewsFolder) : viewsFolder; } } @Override public void handle(HttpRequest request, HttpResponse response, HttpContext context) throws HttpException, IOException { String view = (String) context.getAttribute(ATTR_VIEW); if (view == null) { return; } view = getViewPath(request.getRequestLine().getUri(), view); ByteArrayOutputStream baos = new ByteArrayOutputStream(); Writer out = new OutputStreamWriter(baos); try { Template t = engine.getTemplate(view); t.merge(buildContext(request, (HttpSessionContext) context), out); out.flush(); } catch (ResourceNotFoundException e) { response.setStatusLine(HttpVersion.HTTP_1_1, HttpStatus.SC_NOT_FOUND, "View " + view + " not found."); return; } catch (ParseErrorException e) { throw new HttpException("Parse error evaluating " + view + ": " + e, e); } catch (MethodInvocationException e) { throw new HttpException("Method invocation error evaluating " + view + ": " + e, e); } BasicHttpEntity body = (BasicHttpEntity) response.getEntity(); body.setContentLength(baos.size()); body.setContent(new ByteArrayInputStream(baos.toByteArray())); if ((body.getContentType() == null) || StringUtils.isBlank(body.getContentType().getValue())) { body.setContentType(ContentType.TEXT_HTML.getMimeType()); } } /** * @return the engine */ public VelocityEngine getEngine() { return engine; } // --------------------------------------------------------- Private methods /** * Creates a velocity context filling it with all request parameters and * attributes (the former overwrite the latter). * * @param request the request to create the context upon * * @return the newly created context */ private VelocityContext buildContext(HttpRequest request, HttpSessionContext httpContext) { VelocityContext context = new VelocityContext(); for (String name : httpContext.keySet()) { context.put(name, httpContext.getAttribute(name)); } try { URI uri = new URI(request.getRequestLine().getUri()); QueryString qs = QueryString.parse(uri.getQuery()); for (String name : qs.getNames()) { context.put(name, qs.get(name)); } } catch (URISyntaxException x) { // // if the URL is marformed, there is nothing to do here... // } return context; } private String getViewPath(final String uri, final String view) throws HttpException { try { File uriFile = new File(new URI(uri).getPath()); File viewFile = new File(uriFile.getParent(), new File(viewsFolder, view).getPath()); return viewFile.getPath(); } catch (URISyntaxException x) { throw new HttpException("URI syntax error for '" + uri + "'", x); } } }