Friday
Jun 26, 2009
5:05 pm
A Breadcrumb Story
Where I work, one of the site features is a breadcrumb trail on all pages allowing linking through the content hierarchy. All of the breadcrumbs in the breadcrumb trail was generated using a rather lengthy Javascript file. The main reason for the length was due how the folders were named and the number of exceptions or special cases. As a note, for this to work all directory names were CamelCase (lowerCamelCase, to be precise) except where they were legacy items or inconsistently named (increasing the number of special cases that needed handling).
But it worked better than much breadcrumb code I’ve seen, so all was well and good until two things happened. The first was that mysterious 404 errors began to crop up in our logs. I finally traced them back to bots crawling the site, coming across the pieces of the Javascript that constructed the links in the breadcrumbs and indexing them as valid (not processed) links. So our logs were littered with failures to find pages like about_gh/.*/badministrator/b.*)/i, or /health_plans/+howmany[i+2]+. The second thing that occurred was we began developing a new version of one of our sites and it didn’t make sense to use the existing Javascript since the majority of it’s special cases were for our main site. Further, we would just be perpetuating the log errors caused by misbehaving seach engine bots.
So, for the new site, I rewrote the Javascript as a JHTML include. Since we’re using Dynamo and haven’t migrated any of our dynamic pages to be JSP pages (and encountered some problems with that due to the older version we’re running on), I learned some interesting things about using Java inline on a single page like this.
The first part of the page requires declaring any imports, like so:
<java type="import"> java.util.regex.*; </java>
The second part of the page is the main Java code that gets the URL and performs some operations on it:
<java> String originalURL = request.getRequestURL().toString(); if (originalURL.indexOf("somejavaAppPathID") != -1) { if (originalURL.indexOf("javaApp") != -1) { breadcrumbPathString += divider + "<a href=\"/somespecialidentifierParent/index.jhtml\">JavaAppParent</a>" + divider + "<a href=\"/somejavaAppPathID/javaApp/JavaAppMethod?forwardUrl_success=/someAppResultLocation/javaApp/index.jhtml\">JavaApp</a>"; } } else if (originalURL.indexOf("pageNameWithParam.jhtml") != -1) { //itemKey is the parameter that has the path to the content String paramKey = "paramname"; breadcrumbPathString = makeTrail(request.getParameter( paramKey ), baseLoc, divider); } else { breadcrumbPathString = makeTrail(request.getRequestURI(), baseLoc, divider); } breadcrumbPathString = fixDirectories(breadcrumbPathString); out.print(breadcrumbPathString); </java>
Originally, my thought was to use the Request Scheme like this:
String thisRequestScheme = request.getScheme(); if (thisRequestScheme.startsWith("https") == true) { baseLoc ="https://"+ request.getServerName() ; } else{ baseLoc ="http://"+ request.getServerName() ; } if (request.getServerPort() != 0) { baseLoc += ":"+request.getServerPort(); }
But since our server configuration includes F5 load balancers, that was incorrect and the request object contains different information than the URL we’re looking for. I’d prefer to use this implementation, but the previous one starting with request.getRequestURL() will work.
Lastly, I created some methods for handling special cases and doing some other work on the URLs:
<java type="class"> public String makeTrail(String breadCrumb, String urlPath, String thisDivider) throws IOException { urlPath += "/"; String outputString = "<a href=\""+urlPath+"index.jhtml\">Home</a>"; String linkName = ""; String linkString = breadCrumb; breadCrumb = removeDirectories(breadCrumb); if (breadCrumb != null) { String[] breadCrumbArr = breadCrumb.split("/"); String[] linkStringArr = linkString.split("/"); if(breadCrumbArr.length!=0) { for(int i=1; i<linkStringArr.length-1; i++) { urlPath += linkStringArr[i]+"/"; if (breadCrumbArr[i] != null && breadCrumbArr[i].length() > 0) { linkName = makeProper(breadCrumbArr[i]); outputString += thisDivider+"<a href=\""+urlPath+"index.jhtml\">"+linkName+"</a>" ; } } } } return outputString; } public String makeProper(String theString) throws IOException { StringReader in = new StringReader(theString); boolean precededBySpace = true; boolean precededByCap = true; StringBuffer properCase = new StringBuffer(); while(true) { int i = in.read(); if (i == -1) break; char c = (char)i; if (Character.isSpaceChar(c)) { properCase.append(c); precededBySpace = true; } else if (Character.isUpperCase(c)) { if (precededByCap) { properCase.append(c); } else { properCase.append(' '); properCase.append(c); } precededByCap = true; } else if (c == '-'||c == '_') { properCase.append(' '); precededBySpace = true; } else { if (precededBySpace) { properCase.append(Character.toUpperCase(c)); } else { properCase.append(Character.toLowerCase(c)); } precededBySpace = false; precededByCap = false; } } return properCase.toString(); } public String removeDirectories(String theString) { //completely remove these directories from the breadcrumbs theString = replaceWith(theString,"ignore/","/"); theString = replaceWith(theString,"anotherDirectoryToSkip/","/"); return theString; } public String fixDirectories(String theString) { //replace these nonsense names with real words // theString.replaceWith("(?i)\\babout[ _]us\\b","About Us"); //A weird special case since the directory name is not CamelCase theString = replaceWith(theString,"(?i)\\bpeople\\splaces\\b","People & Places"); theString = replaceWith(theString,"(?i)\\babbr\\b","Full Unabbreviated Directory Name"); return theString; } private static String replaceWith(String aPath, String aPattern, String aReplacement ){ Pattern pattern = Pattern.compile(aPattern, Pattern.CASE_INSENSITIVE); Matcher matcher = pattern.matcher(aPath); return matcher.replaceAll(aReplacement); } </java>
In reviewing this code, one thing I was unsure about was whether using
String originalURL = request.getRequestURL().toString();
was the correct way to go or if I should have used
String path = request.getPathTranslated(); path = replaceBacklash(path);
I realized that, for the way the site functions, we may pass an item parameter and we want to properly build the path to that item, not the page rendering the item. Using getRequestURL handles both situations.
