The BalusC Code

Welcome

3000-01-01T02:01:00.006-04:00

Welcome at The BalusC Code! This website (let's call it "blog" for now) was originated at a site called "The BalusC Server" which existed since may 1999 and was available on http://balusc.xs4all.nl since june 2001. At 31 august 2007 that site was stopped due to the emigration plans of BalusC and its family from The Netherlands to Curaçao. That site was hosted at a private webserver which was

Communication in JSF 2.0

2011-09-16T19:22:00.057-04:00

Fast menu Introduction Managed bean names Managed bean scopes Injecting managed beans in each other Injecting request parameters in a view scoped bean @ViewScoped fails in tag handlers Implicit navigation Implicit EL objects Implicit output text Normal (synchronous) POST form Ajax (asynchronous) POST form Ajax validation Ajax rendering of content outside form Ajax rendering of content which

JSF 2.0 tutorial with Eclipse and Glassfish

2011-01-30T23:24:00.031-04:00

Fast menu Introduction Preparing Download and install Java SE 6 JDK Download and install Java EE 6 Web Profile SDK Download and install Eclipse Helios 3.6 SR1 Run and configure Eclipse Integrate Glassfish in Eclipse Prepare JSF web project in Eclipse Create JSF hello world in Eclipse - The model Create JSF hello world in Eclipse - The controller Create JSF hello world

Internationalization in JSF with UTF-8 encoded properties files

2010-10-29T12:23:00.003-04:00

For my current employer I get paid to -among others of course- write blogs for the local development team. Those blogs are fortunately available online for everyone. So, here's just a link instead of a copypaste ;) Internationalization in JSF with UTF-8 encoded properties files I must admit that I miss the lack of syntax highlighting over there as well, we would need to look for a Wordpress

Disadvantages of JSF, a bit of history

2010-09-05T14:13:00.001-04:00

This is a copy of my answer on stackoverflow.com. JSF 2.0 disadvantages? Honestly, no serious disadvantages comes to mind. JSF in its current release still need to get rid of the negative imago as it was grown during the early ages. In the history there were indeed several serious disadvantages. JSF 1.0 (March 2004) This was the initial release. It was cluttered of bugs in both the core and

Using the MVC design pattern with JSP/Servlet

2010-08-22T00:33:00.004-04:00

This is a copy of my answer on stackoverflow. A bit decent webapplication exist of a mix of design patterns. I'll mention only the most important ones. Model View Controller pattern The core (architectural) design pattern you'd like to use is the Model-View-Controller pattern. The Controller is to be represented by a Servlet which (in)directly creates/uses a specific Model and View based

Using HTML in JSF messages

2010-07-29T17:53:00.004-04:00

A common question which keeps returning is "How to display HTML in ?". One would logically think to add an escape="false" attribute to the component, like as you would do in a . Unfortunately, this is not possible in the standard JSF implementation. The component and the renderer does officially not support this attribute. The and are as far

How to avoid Java code in JSP files?

2010-07-05T10:19:00.002-04:00

This is a copy of my answer on stackoverflow.com. The use of scriptlets (those <% %> things) is indeed highly discouraged since the birth of taglibs (like JSTL) and EL (Expression Language, those ${} things) over a decade ago. The major disadvantages of scriptlets are: Reusability: you can't reuse scriptlets. Replaceability: you can't make scriptlets abstract. OO-ability: you can't make use

Servlet lifecycle and multithreading

2010-06-24T10:41:00.000-04:00

This is a copy of my answer on stackoverflow.com. ServletContext When the servletcontainer (like Apache Tomcat) starts up, it will deploy and load all webapplications. When a webapplication get loaded, the servletcontainer will create the ServletContext once and keep in server's memory. The webapp's web.xml will be parsed and every Servlet, Filter and Listener found in web.xml will be created

The benefits and pitfalls of @ViewScoped

2010-06-05T23:18:00.051-04:00

Fast menu Introduction Really simple CRUD Really simple CRUD, now without DataModel! Hey, there's "pitfalls" in the title? Introduction To prepare for a new set of JSF 2.0 targeted articles (have patience, I'd like to wait for Eclipse Helios and Tomcat 7 to be finished), I've played intensively with JSF 2.0 and Facelets the last

Real world Java examples of GoF design patterns

2010-04-25T01:51:00.007-04:00

This is a copy of my answer on stackoverflow. GoF stands for Gang of Four, referring the four authors of the Design Patterns book. You can find an overview of a lot design patterns in Wikipedia. It also mentions which patterns are mentioned by GoF. I'll sum them up here and try to assign as much as possible pattern implementations found in both the Java SE and Java EE API's. Creational

Hidden features of JSP/Servlet

2010-01-27T02:39:00.000-04:00

This is a copy of my answer on stackoverflow.com. Hide JSP pages from direct access By placing JSP files in /WEB-INF folder you effectively hide them from direct access by for example http://example.com/contextname/WEB-INF/page.jsp. This will result in a 404. You can then only access them by a RequestDispatcher in Servlet or using jsp:include. Preprocess request for JSP Most are aware

What is the difference between JSF, JSP and Servlet?

2010-01-19T18:39:00.003-04:00

This is a copy of my answer on stackoverflow. JSP (JavaServer Pages) JSP is a Java view technology running on the server machine which allows you to write template text in (the client side languages like HTML, CSS, JavaScript and so on). JSP supports the so-called taglibs which are backed by pieces of Java code with which you can control the page flow and/or output dynamically (

Uploading files with JSF 2.0 and Servlet 3.0

2009-12-27T17:35:00.034-04:00

Fast menu Introduction Custom component and renderer Basic use example Validate uploaded file Introduction The new Servlet 3.0 specification made uploading files really easy. However, because JSF 2.0 isn't initially designed to be primarily used on top of Servlet 3.0 and should be backwards compatible with Servlet 2.5, it lacks a standard file

Uploading files in Servlet 3.0

2009-12-27T16:00:00.043-04:00

Warning The MultipartFilter class does not work in Tomcat 7.0.0 until with 7.0.6! In order to get it to run properly, you need at least Tomcat 7.0.7 and to set allowCasualMultipartParsing="true" in the webapp's element in Webapp/META-INF/context.xml or Tomcat/conf/server.xml. See also Tomcat 7 issue 47911. Fast menu Introduction MultipartMap Basic

Webapplication performance tips and tricks

2009-09-09T21:54:00.042-04:00

Fast menu Introduction Use a Content Delivery Network Add an Expires or a Cache-Control Header Use Query String with a timestamp to force re-request Add LastModified timestamp to CSS background images Gzip Components Configure ETags Flush the Buffer Early Use NIO Introduction Yahoo has a great performance analysis tool in flavor of a Firefox addon: YSlow (yes, you need

Writers block

2009-09-01T14:19:00.014-04:00

What to write? It is not that I'm out of inspiration. Contrary, I have too much inspiration and too little time that I don't know what to write and finish. When I get inspiration, then I start with some introductory text and some code samples and/or notes. But when I run out of time in meanwhile, I leave it for as it is too long until I get inspiration about another subject .. and the story

Java/JSP/JSF and JavaScript

2009-05-24T21:17:00.070-04:00

Fast menu Introduction Server side and client side Pass variables from server side to client side Pass variables from client side to server side Introduction Today I investigated using Google Analytics the search keywords used to find this blog, so that I can get some blogging inspiration based on the "missing hits" (i.e. the actual search incorrectly showed my blog between the

Unicode - How to get the characters right?

2009-05-05T20:33:00.163-04:00

Fast menu Introduction Well, where does it go wrong? Unicode, what's it all about? OK .. So, I have an "Unicode problem", what now? 1) Development environment 2) Java properties files 3) JSP/Servlet request 4) JSP/Servlet response 5) Facelets request/response 6) Databases 7) Text files 8) Strings References Introduction Computers

FileServlet supporting resume and caching and GZIP

2009-02-18T11:22:00.108-04:00

Fast menu Introduction Resume downloads Client side caching GZIP compression The Code Introduction In the almost 2 year old FileServlet and ImageServlet articles you can find basic examples of a download servlet and an image servlet. It does in fact nothing more than obtaining an InputStream of the desired resource/file and writing it to the OutputStream of the HTTP response

Effective datatable paging and sorting

2008-10-10T12:53:00.053-04:00

Fast menu Effective datatable paging and sorting at DAO level Preparations Backing Bean Example DTO Example DAO Example JSF Effective datatable paging and sorting at DAO level In the 2 year old article Using datatables I wrote how to sort and page a JSF h:dataTable. Those are useful and nice if the dataset is small. But it is in fact less efficient as it first

Validate required checkbox

2008-09-20T23:04:00.021-04:00

Fast menu Introduction RequiredCheckboxValidator Basic demonstration example Introduction The required attribute of a h:selectBooleanCheckbox is a bit non-intuitive. If you want to require the user to check the desired checkbox, you would assume that setting the required attribute to true ought to be sufficient. startHide('/2008/09/validate-required-checkbox.html'); But

Styling options in h:selectOneMenu

2008-08-06T21:41:00.020-04:00

Fast menu Introduction ExtendedMenuRenderer Basic demonstration example And the listboxes then? Introduction Whenever you want to style a HTML

DAO tutorial - use in JSF

2008-07-29T12:22:00.046-04:00

Fast menu Introduction Webapp configurator User registration bean Abstract bean for user forms Abstract bean for forms EmptyToNullConverter Message bundle file User registration JSF File CSS file and JavaScript file Web deployment descriptor Faces configuration XML Introduction This tutorial is a JSF-targeted continuation from the previous part DAO tutorial - the

DAO tutorial - use in JSP/Servlet

2008-07-07T14:22:00.095-04:00

Fast menu Introduction Webapp configurator User registration controller Base bean for forms Business form bean for User ValidatorException Utility class for forms User registration JSP File CSS file JavaScript file Web deployment descriptor Further exercises Introduction This tutorial is a continuation from the previous part DAO tutorial - the data layer. In the

DAO tutorial - the data layer

2008-07-07T14:21:00.150-04:00

Fast menu Introduction The data layer Preparing database User DTO Handling DAO exceptions Properties file Properties file loader DAO factory User DAO DAO utility class DAO test harness Further exercises How about connection pooling? Next part Introduction In almost every application there is less or more interaction with a database or any

What is it with roseindia?

2008-06-28T23:13:00.048-04:00

Cry or laugh? There's another Java related website at roseindia.net which hosts lot of basic Java EE tutorials along a huge mass of advertisements. There are also some JSF tutorials over there. Since I saw that site for the first time, about 1.5 years ago, I quickly realized that almost every article and code sample at that site must be taken with a huge bag of salt. But OK, I thought, that kind

Uploading files with JSF

2008-02-16T16:37:00.025-04:00

Notice This article is targeted on JSF 1.2. For JSF 2.0 with Tomahawk, please checkout my answer on this Stackoverflow.com question. For JSF 2.0 on Servlet 3.0 with a custom component, please checkout this article. Fast menu Upload and store files Integrating Tomahawk in Mojarra Basic use example Upload and store files

JSF tutorial with Eclipse and Tomcat

2008-01-04T15:12:00.044-04:00

Notice There is a newer JSF 2.0 tutorial out with Eclipse 3.6 SR1 (Helios) and Glassfish v3. Fast menu Introduction Download and install Java SE 6 JDK Download and install Eclipse 3.4 Download and install Tomcat 6.0 Download and install JSTL 1.2 Download and install Mojarra 1.2 Run and configure Eclipse Integrate Tomcat in Eclipse Prepare JSF web project in Eclipse

Action dependent requireness

2007-12-19T06:46:00.002-04:00

Introduction There are scenarios where you want to depend the "requireness" (between quotes, this word doesn't occur in an English dictionary) of an UIInput element on the UICommand action invoked. There are also a lot of hacks and workarounds written about it, e.g. using immediate="true" and valueChangeListener or binding attributes to retain the value (which gives you only two scenario

Set focus and highlight in JSF

2007-12-14T07:05:00.015-04:00

The power of a PhaseListener This article shows how to use a PhaseListener to set focus to the first input element which has a FacesMessage (which can be caused by a validation or conversion error or any other custom reason) and highlight all elements which has a FacesMessage. It is relatively simple, it costs effectively only a few lines inside the beforePhase of the RENDER_RESPONSE, two

Validator for multiple fields

2007-12-11T17:07:00.014-04:00

Fast menu Introduction Basic example Introduction Validators in JSF are nice. They, however, have its shortcomings. They will by default validate only one field at once. There is no standard way to attach one validator to multiple fields. Although there are some situations where you want this kind of functionality. For example

WhitespaceFilter

2007-12-01T06:26:00.012-04:00

Fast menu Whitespace Replace response writer Whitespace Whitespace is used everywhere. It covers spaces, tabs and newlines. It is used to distinguish lexical tokens from each other and also to keep the source code readable for the developer. But in case of HTML over network, whitespace costs bandwidth and therefore in some circumstances

MultipartFilter

2007-11-08T03:15:00.016-04:00

Fast menu Upload and store files MultipartFilter Basic use example Upload and store files Update: if you're using Servlet 3.0 or newer, then there are built-in ways to process file uploads. You may find it more useful: Uploading files in Servlet 3.0. Downloading files is made relatively easy using a FileServlet, but uploading

Populate child menu's

2007-10-17T15:11:00.012-04:00

Fast menu Introduction Onchange, valueChangeListener, immediate, renderResponse and binding Basic JSF code example Menu structure Introduction Having multiple h:selectOneMenu instances in one form which depends on each other and of which its values have to be obtained from the backing bean can drive JSF developers nuts.

DateUtil

2007-09-15T17:24:00.006-04:00

Useful date utilities An utility class with some fairly simple methods and some very useful methods (such as determineDateFormat()). This utility class partly wraps the CalendarUtil so that it can be used with Date and String objects. The determineDateFormat() method supports the most commonly used date formats. You can always change or extend it to your taste, but take care that there should

CalendarUtil

2007-09-15T17:12:00.005-04:00

Useful calendar utilities An utility class with some fairly simple methods and some very useful methods. The elapsedXxxx methods are absolutely useful. If you want to use it with java.util.Date or even java.lang.String objects, then you may find the DateUtil more useful. startHide('/2007/09/calendarutil.html'); /* * net/balusc/util/CalendarUtil.java * * Copyright (C) 2007 BalusC * * This

FileUtil

2007-09-10T06:05:00.020-04:00

Useful filesystem level utilities I'd like to share this utility class with lot of useful filesystem level utility methods. It minimizes the effort of the developer to write code for java.io stuff. Just call the utility method in a try-catch-finally block and handle the eventual IOException to your taste. startHide('/2007/09/fileutil.html'); /* * net/balusc/util/FileUtil.java * * Copyright (

Objects in h:selectOneMenu

2007-09-07T16:20:00.015-04:00

Fast menu Introduction Using a Converter Using a backing Map Introduction A HTML response is in Object Oriented perspective nothing less or more than one big String value (technically: a long character array). Non-String-typed Java Objects are forced to their String representation using Object#toString() when they are

Generic object converter

2007-08-05T20:38:00.026-04:00

Generic Object Converter This generic ObjectConverter makes use of the reflection and the generics to convert the given object value to an object of the given type. This utility class may look like overkilled, but it is very useful if you don't always know the type of the given object value before or if you want a fast and easy way of converting objects without nasty if/else blocks. BalusC

FileServlet

2007-07-20T21:46:00.040-04:00

Fast menu Serve your files FileServlet serving from absolute path FileServlet serving from database Security considerations Serve your files Update: there's a newer article out for more effective file serving. You may find it useful: FileServlet supporting resume and caching and GZIP. If you have stored

ImageServlet

2007-04-08T05:05:00.039-04:00

Fast menu Serve your images ImageServlet serving from absolute path ImageServlet serving from database Security considerations Serve your images Update: there's a newer article out for more effective file serving. You may find it useful: FileServlet supporting resume and caching and GZIP. If you have stored images in a

User session filter

2007-03-20T03:30:00.022-04:00

Fast menu Introduction Capture the User Prepare DTO's UserSessionFilter Login and Logout Security considerations Capture the User By default a HTTP session will expire after 30 minutes of inactivity. Although you can change this by the following entry in the web.xml, where the timeout can be set in

Facade POST by GET

2007-03-19T18:04:00.001-04:00

Fast menu Introduction Passing GET parameters to backing beans Facade POST requests like it are GET requests Hide parameters Introduction By default the JSF-generated forms only provides POST functionality. There is no default option to transform the POST forms (

POST-Redirect-GET pattern

2007-03-19T18:03:00.022-04:00

Doing the PRG in JSF The POST-Redirect-GET pattern is commonly used in web applications to prevent double submit when refreshing a POST request and navigation problems/annoyances when using browser back/forward button to page between POST requests. Basically it works as follows: after processing the POST request (unnecessarily submitted/displayed form data and/or irritating "Are you sure to

JDBC tutorial (Dutch)

2007-03-02T02:41:00.015-04:00

Snelmenu Introductie Foutenafhandeling JDBC driver installeren Database voorbereiden JDBC URL voorbereiden Eenvoudige INSERT Eenvoudige SELECT Eenvoudige UPDATE Eenvoudige DELETE Voorbereide statementen DTO's zijn een must Een universele DAO ontwerpen? Introductie

Generics (Dutch)

2007-01-31T19:00:00.001-04:00

Snelmenu Introductie Generieke collecties Generieke mappen Generieke klassen Generieke methoden Generieke typen Introductie Generics, oftwel Generieken, die in Java 5.0 is geintroduceerd slaat op de harde typering van de gebruikte objecten in collecties, mappen, klassen en methoden. Het gebruik hiervan is

Dynamic JSF subviews

2007-01-04T11:42:00.009-04:00

Dynamically switch between subviews in one main page The easiest way would be the following: But this only works in JSF 1.2 + JSP 2.1 or newer. Unified Expression Language (the expressions starting with #) namely made its way from JSF to JSP in JSP 2.1. In older versioned environments the above snippet is not valid. To have JSP 2.1, you need a

Debug JSF lifecycle

2006-09-27T12:05:00.035-04:00

Fast menu Listen and debug JSF lifecycle phases Basic debug example The first call The form submit Add immediate="true" to UIInput only Add immediate="true" to UICommand only Add immediate="true" to UIInput and UICommand Conversion error Validation error Okay, when should I use the immediate attribute

Bestandsbewerkingen (Dutch)

2006-06-26T09:32:00.004-04:00

Snelmenu Introductie Welke moet ik gebruiken? Foutenafhandeling Werken op bestandsniveau Werken op directory niveau FileReader en FileWriter BufferedReader en BufferedWriter CharArrayReader en CharArrayWriter FileInputStream en FileOutputStream BufferedInputStream en BufferedOutputStream

Parse CSV upload

2006-06-13T08:32:00.023-04:00

Fast menu How easy can it be done? Uploading a CSV file using IBM faces Parsing and formatting the CSV file CSV formatting example How easy can it be done? CSV files are commaseparated files and can be opened and saved using Microsoft Excel. However, in most locales (at least US International and Europe) Excel uses a semicolon

Using datatables

2006-06-07T03:11:00.068-04:00

Notice This article is targeted on JSF 1.2. For JSF 2.0, using datatables can be approached much more elegantly with help of a @ViewScoped managed bean. Please checkout this article which contains two basic CRUD examples, one for JSF 2.0 on Srvlet 2.5 and other for JSF 2.0 on Servlet 3.0 which supports passing method arguments in EL 2.2. Fast menu Create DTO class

Collecties en mappen (Dutch)

2006-06-05T17:38:00.001-04:00

Snelmenu Introductie Welke moet ik gebruiken? Waarden toevoegen Waarden opvragen Aanwezigheid controleren Waarden wijzigen Waarden verwijderen Grootte opvragen Leeg maken Collectie doorlopen Map doorlopen Collectie sorteren Collecties samenvoegen en splitsen Duplicaten

Data conversies (Dutch)

2006-06-04T18:43:00.001-04:00

Snelmenu Converteren van datatype naar String Converteren van String naar datatype Converteren van datatype naar wrapper object Converteren van wrapper object naar datatype Converteren tussen datatypen Converteren tussen nummerieke systemen Converteren tussen data streams Converteren van datatype naar

DB2 LOWER() bug

2006-06-04T16:10:00.004-04:00

Case insensitive search in a table with a foreign key The goal is to execute a case insensitive Hibernate search in a DB2 table which has a foreign key linked to another DB2 table. This should be easily done using the LOWER() function of DB2. startHide('/2006/06/db2-lower-bug.html'); The relevant DDL of the DB2 table to execute the search on, MyTable.ddl: CREATE TABLE MYTABLE (

Datum en tijd (Dutch)

2006-06-04T01:21:00.001-04:00

Snelmenu Introductie Datum en tijd instellen Converteren tussen Date en Calendar Converteren tussen Calendar en String Converteren tussen Date en String Verschil tussen datums berekenen Unix TimeStamp in Java Werken met Unix TimeStamps Introductie Java kent twee hoofdklassen waarmee je met

Communication in JSF

2006-06-03T17:00:00.030-04:00

Notice This article is targeted on JSF 1.x. For JSF 2.x, please checkout this article. Fast menu Passing action parameters from JSF to backing beans Passing GET parameters from JSF to backing beans Passing component attributes from JSF to backing beans Passing objects from request to request Passing new hidden values to backing beans

PDF handling

2006-05-21T05:01:00.013-04:00

Read and open the PDF in a new browser window The goal is to use JSF to open a PDF file inline in a new browser window without showing the full PDF path and filename for some (security) reasons. You can use either a h:commandLink or a h:commandButton for this: