Survey of J2EE open source tools and libraries

I came across this excellent collection of open source tools and tag libraries with a focus on Java / J2EE tools. There are links and reviews of open source AJAX frameworks, content management systems, J2EE Frameworks, JSP tag libraries and a lot of other goodies.
Most of the topic reference links are active and the content is relatively current. Worth bookmarking if you are working in the Java domain and want to see some of the various open-source offerings on a particular subject.

While on the subject of surveying J2EE tools, an interesting book on the market is Java Power Tools. While the book is basically a compendium of 30 tools ranging from version control systems to QA analysis tools, it tends to gravitate a lot towards the use of Unit testing, Continuous Integration and Stress and Volume testing tools. A look at the TOC doesn't reveal much for the experienced developer but for the newbie J2EE guy, this might be a good starting point. I would have liked it a lot more, if it had a chapter on application servers and 'compared' different frameworks (albeit briefly) such as Struts and Tapestry or Struts and Cocoon. I also missed Hibernate in the TOC. :-( But overall, it looks to be a good read for a newbie.

Curvy Corners in Web Pages ..without digital editing

With the influx of 'Web2.0' look and feel web-sites, the prevalence of curvy corners has caught the imagination of web-designers. While the majority of web sites having curvy corners require digital editing. In simple language, you would normally create an image with curved corners, cut off the corners and stick it into your web-page to get the appropriate look. However, if you aren't much of a digital web-designer, you would prefer to go in for curvy corners.

Curvy corners is a free Javascript library that allows you to create on-the-fly DIVs with curved corners. While implementing the library and using it to get the required effect is easy, some tinkering might be required to your own CSS files before you can get it work.
The logic behind curvy corners is that it 'straps' on 20px to your existing DIVs. The additional 20 px inherit the look and feel of the DIV element that you specify and so they look like a natural extension of the same div.

A few problems that you should watch out for is that padding within the specified DIV (that gets curvy corners applied to it) disappears. You can configure the padding parameter to come back on by setting the auto-pad flag to true but it applies padding by implementing a work-around. The 'work-around' is an inner DIV that is created on the fly and all text that was a part of the original DIV gets moved into the inner DIV. Thus, the original DIV becomes a parent of the new 'inner' DIV. In my case, this broke some of the other JavaScript functionality, like my DateTime picker stopped working as it could not figure out the DIV that it belonged to.

To summarise, while Curvy Corners is an excellent snappy script that gives you curvy corners without digital editing, it may mess up some of your existing Javascript libraries so be sure to test your application in FF and IE after applying curvy corners. Happy Rounding Off!!

Implementing pagination in JSPs

I recently implemented Pagination in my JSPs so that if there were several results returned by a query (Search function), the user could view the results in a page-wise format. The image on the right is what I ended up with after implementing pagination through an open-source tag library, displaytags. In this post I will explain the basic steps that I followed in order to install and use the tag library.

While implementing pagination is not a complex task as there are only a few scenarios that need to be taken care off, I preferred to use a taglib to implement the same. While the web and Google will throw up several solutions, I tried implementing the pager taglib available at JSPTags first.

The pager taglib has several look and feel features available, I was not happy with the documentation and examples provided and after struggling with the installation of the taglib, I gave it up in favor of the displayTags taglib. I found this library easy to install and use, with a good mixture of code examples and features. Needless to say, I was able to achieve my objective.

Here I will show you the basic steps of setting up the pagination feature using the displayTags library in a Struts based JSP that is deployed on a JBOSS server (version 4.04) running on Java 1.5. Okay, lets get started. We will do this in steps.

1.Download the displayTags library (At the time of writing version displaytag-1.1.1.jar is the latest jar). In the download, you will also get a WAR file that you can directly drop into your web-server and view the examples. But for setting the tagLib for your own use, you are best off extracting (unzipping) the WAR and using the files inside.

Extract the displaytag-1.1.1.jar and place it into your WEB-INF/lib directory.
I did not need to add a directive in my web.xml as I am using JSP2.0. (Tomcat 5.5)

You will also need to make sure that the commons-* jars that come with the displayTags download are available in the WEB-INF\lib directory.

2. In your JSP,add the following directive:
<%@ taglib uri="http://displaytag.sf.net" prefix="display" %>

3. You may wish to add the CSS styles available in the downloaded displayTags library. There are several theme css files that can be used and I chose to use the file (displaytag.css). Drop this file into your style sheets directory within your WEB-INF and reference it in your JSP.

Be aware that the data that will be displayed by the tagLibrary will be within a table and sometimes nesting a table within a table (if your JSP has one) can cause display problems but in my case, I had a very simple layout so I was fine.

4. Now add the displayTags that will display the data in a paginated format.
Add the following lines to your JSP:
The table name in this case, requestScope.SEARCH_RESULTS_LIST matches the name of a List that has been placed into the request scope by the servlet (Action class) that forwarded to this JSP. So for this table name to be workable, I have a list that I set in the servlet using the following line of code.

request.setAttribute("SEARCH_RESULTS_LIST", searchResults);

In the list, searchResults, I have a row of String data which is named as searchResultRow (set as the property name in line 6 above). The variable base (on line 1) points to the URL that I want page links to forward to.

Lines 3 and 4 are display properties that you can set to control the look and feel of the paginated data results. A more detailed list of what can be done is available here.
Another feature that is advantageous is that data that is presented in a grid layout can have sortable column headers. In other words, clicking on a column will sort the data displayed on the page.

Well, thats it. Build and Deploy your application and if all goes well, you'll have pagination going with no problems. This is what my page looked like, after I finished.