Java tutorial
/* * Copyright 2000-2004 The Apache Software Foundation. * * 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. */ /* * * * COMPATIBILITY * * [28.01.2001, RammerI] Tested on W2K, with J2SE, JDK 1.3 * [29.01.2001, RammerI] Tested on W2K, with JDK 1.2.2 * * * * FEATURES * = Rewriting of <A HREFs, <IMG SRCes, <FORM ACTIONs, <TD BACKGROUNDs, * <INPUT SRCs, <APPLET CODEBASEs * = Removal of <SCRIPT>, <STYLE>, <HEAD>, <EMBED>, <OBJECT>, <APPLET>, * <NOSCRIPT> * **** * Please include the following section in the WebPagePortlet documentation **** * <CODE> * * The following describes how HTML tags are rewritten * * <!-- --> (HTML Comments) * o Unless otherwise mentioned, comments are striped. * * <A> * o HREF attribute - URL merged with base URL (See Note 1) * o TARGET attribute - Set to "_BLANK" if it does not exist * and openInNewWindow = TRUE * <AREA> * o HREF attribute - URL merged with base URL (See Note 1) * o TARGET attribute - Set to "_BLANK" if it does not exist * and openInNewWindow = TRUE * <APPLET> * o Optionally included * o CODEBASE attribute - Set to the current path if it does * not exist. * * <BASE> * o <HEAD> does NOT have to be included. * o HREF attribute - Set the Base URL of the page, but the tag * not set in resulting HTML. URL merged with * base URL (See Note 1) * * <BODY> * o Background attribute - Always striped. * * <EMBED> * o May not work. Not supported by JDK 1.3/ * * <FORM> * o ACTION attribute - Set to the current URL if it does * not exist. URL merged with base * URL (See Note 1) * * <IMG> * o SRC attribute - URL merged with base URL (See Note 1) * * <INPUT> * o SRC attribute - URL merged with base URL (See Note 1) * * <LINK> * o HREF attribute - URL merged with base URL (See Note 1) * * <OBJECT> * o Optionally included * o CODEBASE attribute - Set to the current path if it does * not exist. URL merged with base * URL (See Note 1) * * <SCRIPT> * o Optionally included * o Contents may be striped if this tag appears in the <HEAD> * and the contents are NOT in a comment * o SRC attribute - URL merged with base URL (See Note 1) * o Script code that is NOT enclosed in a comment (<!-- -->) * and in the <HEAD> may NOT be in the resulting HTML. This * is related to the HTML parser in included in the JDK * * <TD> * o BACKGROUND attribute - URL merged with base URL (See Note 1) * * Note 1: URL Merging. * This is done because the source of the page sent to the * user's browser is different then source the current page. * Example: * Base URL........ http://jakarta.apache.org/jetspeed * URL............. logo.gif * Resulting URL... http://jakarta.apache.org/jetspeed/logo.gif * * </CODE> * KNOWN PROBLEMS * * * == Seems to have problems with international characters, when the web-pages * are not downloaded from the original URL but taken from the cache. * (To reproduce do the following * 1. create a new portlet from the url http://www.sycom.at/default.htm * 2. stop tomcat & restart tomcat * 3. login and customize your page to include this portlet * 4. everything should appear fine, the webpage will show some german * umlauts * 5. shutdown tomcat and restart it * 6. jetspeed is now taking the HTML not from www.sycom.at, but from the * cache. Instead of the umlauts, you will see weird characters. * * * == Does not yet work with XHTML-Pages but only plain-old HTMLs. I.e. Closed * single tags like <BR /> screw the output up. * * * */ //package org.apache.jetspeed.util; import java.io.Reader; import java.io.StringWriter; import java.net.MalformedURLException; import java.net.URL; import java.util.Enumeration; import javax.swing.text.html.HTML; import javax.swing.text.html.HTMLEditorKit; import javax.swing.text.MutableAttributeSet; /** * * @author Ingo Rammer (rammer@sycom.at) * @author <a href="mailto:sgala@apache.org">Santiago Gala</a> * @author <a href="mailto:paulsp@apache.org">Paul Spencer</a> * @version 0.2 */ public class HTMLRewriter { /** * Static initialization of the logger for this class */ private HTMLRewriter.Callback cb = new HTMLRewriter.Callback(); /** Sets the parameters for the HTMLRewriter * @param removeScript Shall SCRIPT-Tags and their content be removed * @param removeStyle Shall STYLE-Tags and their content be removed * @param removeNoScript Shall NOSCRIPT-Tags and their content be removed * @param removeMeta Shall META-Tags be removed * @param removeApplet Shall APPLET-Tags and their content be removed * @param removeObject Shall OBJECT-Tags and their content be removed * @param removeHead Shall HEAD-Tags and their content be removed * @param removeOnSomething Shall onClick, onBlur, etc. -Attributes be removed */ public HTMLRewriter(boolean removeScript, boolean removeStyle, boolean removeNoScript, boolean removeMeta, boolean removeApplet, boolean removeObject, boolean removeHead, boolean removeOnSomething) { init(removeScript, removeStyle, removeNoScript, removeMeta, removeApplet, removeObject, removeHead, removeOnSomething, false); } /** * Sets the parameters for the HTMLRewriter * @param removeScript Shall SCRIPT-Tags and their content be removed * @param removeStyle Shall STYLE-Tags and their content be removed * @param removeNoScript Shall NOSCRIPT-Tags and their content be removed * @param removeMeta Shall META-Tags be removed * @param removeApplet Shall APPLET-Tags and their content be removed * @param removeObject Shall OBJECT-Tags and their content be removed * @param removeHead Shall HEAD-Tags and their content be removed * @param removeOnSomething Shall onClick, onBlur, etc. -Attributes be removed */ public HTMLRewriter(boolean removeScript, boolean removeStyle, boolean removeNoScript, boolean removeMeta, boolean removeApplet, boolean removeObject, boolean removeHead, boolean removeOnSomething, boolean openInNewWindow) { init(removeScript, removeStyle, removeNoScript, removeMeta, removeApplet, removeObject, removeHead, removeOnSomething, openInNewWindow); } /** * Sets the parameters for the HTMLRewriter * * @param removeScript Shall SCRIPT-Tags and their content be removed * @param removeStyle Shall STYLE-Tags and their content be removed * @param removeNoScript Shall NOSCRIPT-Tags and their content be removed * @param removeMeta Shall META-Tags be removed * @param removeApplet Shall APPLET-Tags and their content be removed * @param removeObject Shall OBJECT-Tags and their content be removed * @param removeHead Shall HEAD-Tags and their content be removed * @param removeOnSomething Shall onClick, onBlur, etc. -Attributes be removed * @param openInNewWindow Shall links set Target="_blank" */ private void init(boolean removeScript, boolean removeStyle, boolean removeNoScript, boolean removeMeta, boolean removeApplet, boolean removeObject, boolean removeHead, boolean removeOnSomething, boolean openInNewWindow) { cb.removeScript = removeScript; cb.removeStyle = removeStyle; cb.removeNoScript = removeNoScript; cb.removeMeta = removeMeta; cb.removeApplet = removeApplet; cb.removeObject = removeObject; cb.removeHead = removeHead; cb.removeOnSomething = removeOnSomething; cb.openInNewWindow = openInNewWindow; } /** * Does the conversion of the HTML * @param HTMLrdr Reader for HTML to be converted * @param BaseUrl URL from which this HTML was taken. We be the base-Url * for all URL-rewritings. * @throws MalformedURLException If the BaseUrl is not a valid URL or if an URL inside * the document could not be converted. Should not happen * normally, even in badly formatted HTML. * @return HTML-String with rewritten URLs and removed (according * to constructor-settings) tags */ public synchronized String convertURLs(Reader HTMLrdr, String BaseUrl) throws MalformedURLException { HTMLEditorKit.Parser parse = new HTMLRewriter.ParserGetter().getParser(); String res = ""; try { if (cb.result != null) { cb.result = null; cb.result = new StringWriter(); } cb.baseUrl = new URL(BaseUrl); parse.parse(HTMLrdr, cb, true); res = cb.getResult(); } catch (Exception e) { //logger.error( "Unable to convertURLS", e ); throw new MalformedURLException(e.toString()); } return res; } /** That Class is needed, because getParser is protected and therefore * only accessibly by a subclass */ class ParserGetter extends HTMLEditorKit { /** This is needed, because getParser is protected * @return Html Parser */ public HTMLEditorKit.Parser getParser() { return super.getParser(); } } class Callback extends HTMLEditorKit.ParserCallback { // the base-url of which the given html comes from. private URL baseUrl; // either handling of <FORM> is buggy, or I made some weird mistake ... // ... JDK 1.3 sends double "</form>"-tags on closing <form> private boolean inForm = false; // when in multi-part ignored tags (like <script> foobar </script>, // <style> foobar </style>, a counter for the nesting-level will be // kept here private int ignoreLevel = 0; private boolean removeScript = true; private boolean removeStyle = true; private boolean removeNoScript = true; private boolean removeMeta = true; private boolean removeApplet = true; private boolean removeObject = true; private boolean removeHead = true; private boolean openInNewWindow = false; // remove the onClick=, onBlur=, etc. - Attributes private boolean removeOnSomething = true; private boolean inScript = false; private boolean inStyle = false; private StringWriter result = new StringWriter(); private Callback() { } private Callback addToResult(Object txt) { // to allow for implementation using Stringbuffer or StringWriter // I don't know yet, which one is better in this case if (ignoreLevel > 0) return this; try { result.write(txt.toString()); } catch (Exception e) { /* ignore */ } return this; } private Callback addToResult(char[] txt) { if (ignoreLevel > 0) return this; try { result.write(txt); } catch (Exception e) { /* ignore */ } return this; } /** Accessor to the Callback's content-String * @return Cleaned and rewritten HTML-Content */ public String getResult() { try { result.flush(); } catch (Exception e) { /* ignore */ } // WARNING: doesn't work, if you remove " " + ... but don't know why String res = " " + result.toString(); return res; } public void flush() throws javax.swing.text.BadLocationException { // nothing to do here ... } /** * Because Scripts and Stlyle sometimes are defined in comments, thoese * will be written. Otherwise comments are removed */ public void handleComment(char[] values, int param) { if (!(inStyle || inScript)) return; try { result.write("<!--"); result.write(values); result.write("-->"); } catch (Exception e) { /* ignore */ } // we ignore them } public void handleEndOfLineString(java.lang.String str) { addToResult("\n"); } public void handleError(java.lang.String str, int param) { // ignored } public void handleSimpleTag(HTML.Tag tag, MutableAttributeSet attrs, int param) { if (removeMeta && (tag == HTML.Tag.META)) { return; } appendTagToResult(tag, attrs); } public void handleStartTag(HTML.Tag tag, MutableAttributeSet attrs, int position) { appendTagToResult(tag, attrs); } public void handleEndTag(HTML.Tag tag, int position) { if ((tag == HTML.Tag.FORM) && (inForm)) { // form handling seems to be buggy addToResult("</").addToResult(tag).addToResult(">"); inForm = false; } else if (tag == HTML.Tag.FORM) { // do nothing! ... i.e. we are now outside of any <FORM>, so a // closing </form> is not really needed ... } else { addToResult("</").addToResult(tag).addToResult(">"); } if ((removeScript == false) && (tag == HTML.Tag.SCRIPT)) { inScript = false; } else if ((removeStyle == false) && (tag == HTML.Tag.STYLE)) { inStyle = false; } if (removeScript && (tag == HTML.Tag.SCRIPT)) { ignoreLevel--; } else if (removeStyle && (tag == HTML.Tag.STYLE)) { ignoreLevel--; } else if (removeHead && (tag == HTML.Tag.HEAD)) { ignoreLevel--; } else if (removeApplet && (tag == HTML.Tag.APPLET)) { ignoreLevel--; } else if (removeObject && (tag == HTML.Tag.OBJECT)) { ignoreLevel--; } else if (removeNoScript && (tag.toString().equalsIgnoreCase("NOSCRIPT"))) { ignoreLevel--; } } private void appendTagToResult(HTML.Tag tag, MutableAttributeSet attrs) { if (tag.toString().equalsIgnoreCase("__ENDOFLINETAG__")) { // jdk 1.2.2 places a tag <__ENDOFLINETAG__> in the result ... // we don't want this one return; } if (tag.toString().equalsIgnoreCase("__IMPLIED__")) { // jdk 1.3 places a tag <__IMPLIED__> in the result ... // we don't want this one return; } convertURLS(tag, attrs); Enumeration e = attrs.getAttributeNames(); if (tag == HTML.Tag.BASE) return; addToResult("<").addToResult(tag); while (e.hasMoreElements()) { Object attr = e.nextElement(); String attrName = attr.toString(); String value = attrs.getAttribute(attr).toString(); // include attribute only when Not(RemoveOnSomething = True and starts with "on") if (!(removeOnSomething && attrName.toLowerCase().startsWith("on") && (attrName.length() > 2))) { // Attribute included addToResult(" ").addToResult(attr).addToResult("=\"").addToResult(value).addToResult("\""); } } addToResult(">"); } /** Here the magic happens. * * If someone wants new types of URLs to be rewritten, add them here * @param tag TAG from the Callback-Interface * @param attrs Attribute-Set from the Callback-Interface */ private void convertURLS(HTML.Tag tag, MutableAttributeSet attrs) { // first we do an URL-rewrite on different tags if (tag == HTML.Tag.A) { if (attrs.getAttribute(HTML.Attribute.HREF) != null) { // ---- CHECKING <A HREF addConvertedAttribute(HTML.Attribute.HREF, attrs); } if ((attrs.getAttribute(HTML.Attribute.TARGET) == null) && cb.openInNewWindow) { attrs.addAttribute(HTML.Attribute.TARGET, "_BLANK"); } } else if (tag == HTML.Tag.AREA) { if (attrs.getAttribute(HTML.Attribute.HREF) != null) { // ---- CHECKING <A HREF addConvertedAttribute(HTML.Attribute.HREF, attrs); } if ((attrs.getAttribute(HTML.Attribute.TARGET) == null) && cb.openInNewWindow) { attrs.addAttribute(HTML.Attribute.TARGET, "_BLANK"); } } else if (((tag == HTML.Tag.IMG) || (tag == HTML.Tag.INPUT) || (tag == HTML.Tag.SCRIPT)) && (attrs.getAttribute(HTML.Attribute.SRC) != null)) { // ---- CHECKING <IMG SRC & <INPUT SRC addConvertedAttribute(HTML.Attribute.SRC, attrs); } else if (tag == HTML.Tag.LINK) { if (attrs.getAttribute(HTML.Attribute.HREF) != null) { // ---- CHECKING <LINK HREF addConvertedAttribute(HTML.Attribute.HREF, attrs); } } else if (tag == HTML.Tag.APPLET) { // ---- CHECKING <APPLET CODEBASE= if (attrs.getAttribute(HTML.Attribute.CODEBASE) == null) { int endOfPath = baseUrl.toString().lastIndexOf("/"); attrs.addAttribute(HTML.Attribute.CODEBASE, baseUrl.toString().substring(0, endOfPath + 1)); } else { addConvertedAttribute(HTML.Attribute.CODEBASE, attrs); } } else if (tag == HTML.Tag.OBJECT) { // ---- CHECKING <OBJECT CODEBASE= if (attrs.getAttribute(HTML.Attribute.CODEBASE) == null) { int endOfPath = baseUrl.toString().lastIndexOf("/"); attrs.addAttribute(HTML.Attribute.CODEBASE, baseUrl.toString().substring(0, endOfPath + 1)); } else { addConvertedAttribute(HTML.Attribute.CODEBASE, attrs); } } else if (tag == HTML.Tag.BODY) { if (attrs.getAttribute(HTML.Attribute.BACKGROUND) != null) { // background images are applied to the ENTIRE page, this remove them! attrs.removeAttribute(HTML.Attribute.BACKGROUND); } } else if (tag == HTML.Tag.BASE) { if (attrs.getAttribute(HTML.Attribute.HREF) != null) { try { baseUrl = new URL(attrs.getAttribute(HTML.Attribute.HREF).toString()); } catch (Throwable t) { // logger.error( "HTMLRewriter: Setting BASE=" // + attrs.getAttribute(HTML.Attribute.HREF).toString() // + t.getMessage()); } attrs.removeAttribute(HTML.Attribute.HREF); } } else if (tag == HTML.Tag.FORM) { // ---- CHECKING <FORM ACTION= inForm = true; // buggy <form> handling in jdk 1.3 if (attrs.getAttribute(HTML.Attribute.ACTION) == null) { //self referencing <FORM> attrs.addAttribute(HTML.Attribute.ACTION, baseUrl.toString()); } else { addConvertedAttribute(HTML.Attribute.ACTION, attrs); } } else if (tag == HTML.Tag.TD) { // ---- CHECKING <TD BACKGROUND= if (!(attrs.getAttribute(HTML.Attribute.BACKGROUND) == null)) { addConvertedAttribute(HTML.Attribute.BACKGROUND, attrs); } } // then we check for ignored tags ... // btw. I know, that this code could be written in a shorter way, but // I think it's more readable like this ... // don't forget to add changes to handleEndTag() as well, else // things will get screwed up! if ((removeScript == false) && (tag == HTML.Tag.SCRIPT)) { inScript = true; } else if ((removeStyle == false) && (tag == HTML.Tag.STYLE)) { inStyle = true; } if (removeScript && (tag == HTML.Tag.SCRIPT)) { ignoreLevel++; } else if (removeStyle && (tag == HTML.Tag.STYLE)) { ignoreLevel++; } else if (removeHead && (tag == HTML.Tag.HEAD)) { ignoreLevel++; } else if (removeApplet && (tag == HTML.Tag.APPLET)) { ignoreLevel++; } else if (removeObject && (tag == HTML.Tag.OBJECT)) { ignoreLevel++; } else if (removeNoScript && (tag.toString().equalsIgnoreCase("NOSCRIPT"))) { ignoreLevel++; } } /** * * Converts the given attribute to base URL, if not null * */ private void addConvertedAttribute(HTML.Attribute attr, MutableAttributeSet attrs) { if (attrs.getAttribute(attr) != null) { String attrSource = attrs.getAttribute(attr).toString(); attrs.addAttribute(attr, generateNewUrl(attrSource)); } } private String generateNewUrl(String oldURL) { try { URL x = new URL(baseUrl, oldURL); return x.toString(); } catch (Throwable t) { if (oldURL.toLowerCase().startsWith("javascript:")) { return oldURL; } //logger.error( "HTMLRewriter: Setting BASE=" //+ baseUrl //+ " Old = " //+ oldURL //+ t.getMessage()); return oldURL; // default behaviour ... } } public void handleText(char[] values, int param) { addToResult(values); } } }