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.shindig.gadgets.rewrite; import org.apache.commons.io.IOUtils; import org.apache.commons.lang.StringUtils; import org.apache.shindig.common.uri.Uri; import org.apache.shindig.gadgets.GadgetException; import org.apache.shindig.gadgets.http.HttpRequest; import org.apache.shindig.gadgets.http.HttpResponse; import org.apache.shindig.gadgets.parse.caja.CajaCssLexerParser; import org.w3c.dom.Element; import java.io.IOException; import java.io.Reader; import java.io.StringReader; import java.io.StringWriter; import java.io.Writer; import java.util.Collections; import java.util.List; import java.util.logging.Level; import java.util.logging.Logger; import com.google.caja.lexer.ParseException; import com.google.common.collect.Lists; import com.google.inject.Inject; /** * Rewrite links to referenced content in a stylesheet */ public class CssRequestRewriter implements RequestRewriter { private static final Logger logger = Logger.getLogger(CssRequestRewriter.class.getName()); private final ContentRewriterFeatureFactory rewriterFeatureFactory; private final CajaCssLexerParser cssParser; private final ProxyingLinkRewriterFactory proxyingLinkRewriterFactory; @Inject public CssRequestRewriter(ContentRewriterFeatureFactory rewriterFeatureFactory, CajaCssLexerParser cssParser, ProxyingLinkRewriterFactory proxyingLinkRewriterFactory) { this.rewriterFeatureFactory = rewriterFeatureFactory; this.cssParser = cssParser; this.proxyingLinkRewriterFactory = proxyingLinkRewriterFactory; } public boolean rewrite(HttpRequest request, HttpResponse original, MutableContent content) { if (!RewriterUtils.isCss(request, original)) { return false; } ContentRewriterFeature feature = rewriterFeatureFactory.get(request); String css = content.getContent(); StringWriter sw = new StringWriter((css.length() * 110) / 100); rewrite(new StringReader(css), request.getUri(), proxyingLinkRewriterFactory.create(request.getGadget(), feature, request.getContainer(), false, request.getIgnoreCache()), sw, false); content.setContent(sw.toString()); return true; } /** * Rewrite the given CSS content and optionally extract the import references. * @param content CSS content * @param source Uri of content * @param rewriter Rewrite urls * @param writer Output * @param extractImports If true remove the import statements from the output and return their * referenced URIs. * @return Empty list of extracted import URIs. */ public List<String> rewrite(Reader content, Uri source, LinkRewriter rewriter, Writer writer, boolean extractImports) { try { String original = IOUtils.toString(content); try { List<Object> stylesheet = cssParser.parse(original); List<String> stringList = rewrite(stylesheet, source, rewriter, extractImports); // Serialize the stylesheet cssParser.serialize(stylesheet, writer); return stringList; } catch (GadgetException ge) { if (ge.getCause() instanceof ParseException) { logger.log(Level.WARNING, "Caja CSS parse failure: " + ge.getCause().getMessage() + " for " + source); writer.write(original); return Collections.emptyList(); } else { throw new RuntimeException(ge); } } } catch (IOException ioe) { throw new RuntimeException(ioe); } } /** * Rewrite the CSS content in a style DOM node. * @param styleNode Rewrite the CSS content of this node * @param source Uri of content * @param rewriter Rewrite urls * @param extractImports If true remove the import statements from the output and return their * referenced URIs. * @return Empty list of extracted import URIs. */ public List<String> rewrite(Element styleNode, Uri source, LinkRewriter rewriter, boolean extractImports) { try { List<Object> stylesheet = cssParser.parse(styleNode.getTextContent()); List<String> imports = rewrite(stylesheet, source, rewriter, extractImports); // Write the rewritten CSS back into the element String content = cssParser.serialize(stylesheet); if (StringUtils.isEmpty(content) || StringUtils.isWhitespace(content)) { // Remove the owning node styleNode.getParentNode().removeChild(styleNode); } else { styleNode.setTextContent(content); } return imports; } catch (GadgetException ge) { if (ge.getCause() instanceof ParseException) { logger.log(Level.WARNING, "Caja CSS parse failure: " + ge.getCause().getMessage() + " for " + source); return Collections.emptyList(); } else { throw new RuntimeException(ge); } } } /** * Rewrite the CSS DOM in place. * @param styleSheet To rewrite * @param source Uri of content * @param rewriter Rewrite urls * @param extractImports If true remove the import statements from the output and return their * referenced URIs. * @return Empty list of extracted import URIs. */ public static List<String> rewrite(List<Object> styleSheet, final Uri source, final LinkRewriter rewriter, final boolean extractImports) { final List<String> imports = Lists.newLinkedList(); for (int i = styleSheet.size() - 1; i >= 0; i--) { if (styleSheet.get(i) instanceof CajaCssLexerParser.ImportDecl) { if (extractImports) { imports.add(0, ((CajaCssLexerParser.ImportDecl) styleSheet.get(i)).getUri()); styleSheet.remove(i); } else { CajaCssLexerParser.ImportDecl importDecl = (CajaCssLexerParser.ImportDecl) styleSheet.get(i); importDecl.setUri(rewriter.rewrite(importDecl.getUri(), source)); } } else if (styleSheet.get(i) instanceof CajaCssLexerParser.UriDecl) { CajaCssLexerParser.UriDecl uriDecl = (CajaCssLexerParser.UriDecl) styleSheet.get(i); uriDecl.setUri(rewriter.rewrite(uriDecl.getUri(), source)); } } return imports; } }