Patrice Secheresse: Blog

BeansBinding: validation error

Mon, 25 Aug 2008 11:28:44 GMT

To continue the previous blog, I will add some explanations about the validator.

For example, I want to validate the age to ensure that it is between 0 and 150. All you need to do is to create a class that extends Validator and implements the method validate().

Here the class AgeValidator:

   1: public class AgeValidator extends Validator<Integer> {   2:     3:     @Override   4:     public Result validate(Integer value) {   5:         if (value < 0 || value > 150) {   6:             return new Result(1, "The age must be between 0 and 150. The value " + value + " is incorrect.");   7:         }   8:         return null;   9:     }  10: }

The method returns a null value if the value is valid.

If an error occurs, you create a result object with a code and/or a description. The code can be useful when you internationalise the application. It could be any object or null.

To add the validator, you just have to set it in the binding: binding.setValidator(new AgeValidator());

So, if you add these lines at the end of our previous run method:

text.setText("151"); //incorrect value, print failure
text.setText("-1"); //incorrect value, print failure

The result will be:

Failure VALIDATION_FAILED: org.jdesktop.beansbinding.Validator$Result [errorCode=1, description=The age must be between 0 and 150. The value 151 is incorrect.]
Failure VALIDATION_FAILED: org.jdesktop.beansbinding.Validator$Result [errorCode=1, description=The age must be between 0 and 150. The value -1 is incorrect.]

You can notice that the type of error is now VALIDATION_FAILED instead of CONVERSION_FAILED.

The validation occurs after the conversion. The idea is to work with the source object type to keep the validation independent of the UI. However, this lead to 2 different systems:

conversion error, based on a RuntimeException to indicate a problem with the conversion
validation error, based on Result object to indicate an incorrect state of the resulting object after conversion

You have to check the failure and display the error depending of the type. Using an unified way to send a failure would have been simpler.

The full code of the main class is:

   1: public class Main {   2:     3:     Person person;   4:     Text text;   5:     6:     public Main() {   7:         person = new Person("John", 21);   8:         text = new Text();   9:     }  10:    11:     /**  12:      * @param args the command line arguments  13:      */  14:     public static void main(String[] args) {  15:         Main test = new Main();  16:         test.run();  17:    18:     }  19:    20:     private void run() {  21:         Property ageProperty = BeanProperty.create("age");  22:         Property textProperty = BeanProperty.create("text");  23:         // bind the persone age to a text component  24:         Binding binding = Bindings.createAutoBinding(UpdateStrategy.READ_WRITE,  25:                 person, ageProperty, text, textProperty);  26:         binding.setValidator(new AgeValidator());  27:         binding.addBindingListener(new AbstractBindingListener() {  28:    29:             @Override  30:             public void syncFailed(Binding binding, SyncFailure failure) {  31:                 System.err.println("Failure " + failure);  32:             }  33:         });  34:         binding.bind();  35:    36:         text.setText("22"); // print value  37:         text.setText("22 and half"); // incorrect value, print failure  38:         text.setText("151"); //incorrect value, print failure  39:         text.setText("-1"); //incorrect value, print failure  40:     }

BeansBinding: conversion error

Thu, 21 Aug 2008 12:02:02 GMT

For a long time I haven't posted anything on this blog. One reason is the finalization of the project VolunteerBase. Since the installation, no news...

Another reason is my new job in OrderMate since March. I am working on an advanced Point Of Sale software for restaurant, café and hospitality. Everything is written in Java, including the new back end which present a rich client interface based on Swing.

The recent evolution uses the BeansBinding library. An excellent blog here details the basic usage of this library and this Java One Technical Session is a good introduction.

An important aspect is the mechanism to convert and validate a property and I will enlarge on it today. To illustrate a basic problem with conversion and validation, I use an integer property bind to a text component. I use the same kind Person class from the John O'Conner blog, with name and age property:

   1: public class Person {   2:     3:     private String name;   4:     private int age;   5:     6:     public Person() {   7:     }   8:     9:     public Person(String name, int age) {  10:         this.name = name;  11:         this.age = age;  12:     }  13:    14:     public int getAge() {  15:         return age;  16:     }  17:    18:     public void setAge(int age) {  19:         this.age = age;  20:     }  21:    22:     public String getName() {  23:         return name;  24:     }  25:    26:     public void setName(String name) {  27:         this.name = name;  28:     }  29: }

The text component is a simple JavaBeans component with only one 'text' property and the property change support. The value is printed each time it is set. The idea is to emulate a JText component.

   1: public class Text {   2:     3:     private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this);   4:     private String text;   5:     6:     public String getText() {   7:         return text;   8:     }   9:    10:     public void setText(String text) {  11:         String oldText = this.text;  12:         this.text = text;  13:         System.out.println("Set text to " + text);  14:         propertySupport.firePropertyChange("text", oldText, text);  15:     }  16:    17:     public void addPropertyChangeListener(PropertyChangeListener listener) {  18:         propertySupport.addPropertyChangeListener(listener);  19:     }  20:    21:     public void removePropertyChangeListener(PropertyChangeListener listener) {  22:         propertySupport.removePropertyChangeListener(listener);  23:     }  24: }

Now, I want to bind the age to the text and simulate the users entry by setting the value of the text.

First, create the properties and bind them: the source is the bean from the data source, the target is generally a visual component. Be careful to respect this, a validator is designed to check that a target value is valid. For today, we won't use a validator:

Property ageProperty = BeanProperty.create("age");
Property textProperty = BeanProperty.create("text");
Binding binding = Bindings.createAutoBinding(UpdateStrategy.READ_WRITE,
person, ageProperty, text, textProperty);
binding.bind();

That's it, any modifications of the text property will go through a default converter and set the age property of the persone:

text.setText("22");

But what happens if the value is incorrect?

text.setText("22 and half");

The answer is... nothing. The default converter from String to integer uses Integer.parseInt((String)value) which throws a NumberFormatException, as stated in the JavaDoc. The exception is caught and the conversion fails. Even creating a validator won't help, the converter is called BEFORE the validator and insulates the application from any Exception. There are three ways to find out what is wrong:

calling the method save() which return a SyncFailure if something is wrong, otherwise set the source value from the target value and set the target value with the new source value
calling the method getSourceValueForTarget() which return a ValueResult if something is wrong but does not modify the source nor the target
add a listener to know when the error occurs

The last solution offers the possibility to react to an incorrect value, for example, in a GUI it will disable the OK button and will set the text field in a different color. In this simple example, it will simply display the error with the added code below:

binding.addBindingListener(new AbstractBindingListener() {
    @Override
    public void syncFailed(Binding binding, SyncFailure failure) {
        System.err.println("Failure " + failure);
    }
});

This code will print:

Failure CONVERSION_FAILED: java.lang.NumberFormatException: For input string: "22 and half"

The full code of the main class is here:

   1: public class Main {   2:     3:     Person person;   4:     Text text;   5:     6:     public Main() {   7:         person = new Person("John", 21);   8:         text = new Text();   9:     }  10:    11:     /**  12:      * @param args the command line arguments  13:      */  14:     public static void main(String[] args) {  15:         Main test = new Main();  16:         test.run();  17:    18:     }  19:    20:     private void run() {  21:         Property ageProperty = BeanProperty.create("age");  22:         Property textProperty = BeanProperty.create("text");  23:         // bind the persone age to a text component  24:         Binding binding = Bindings.createAutoBinding(UpdateStrategy.READ_WRITE,  25:                 person, ageProperty, text, textProperty);  26:         binding.bind();  27:         binding.addBindingListener(new AbstractBindingListener() {  28:    29:             @Override  30:             public void syncFailed(Binding binding, SyncFailure failure) {  31:                 System.err.println("Failure " + failure);  32:             }  33:         });  34:    35:         text.setText("22"); // print value  36:         text.setText("22 and half"); // incorrect value, print failure  37:     }  38: }

This conclude this post, the next step will be adding a validator.

Stable version of VolunteerBase

Sat, 24 Nov 2007 00:50:59 GMT

This version 0.6 of volunteerbase contains fixes and minor improvements, the project is now in a stable phase. The Wiki user guide has a comprehensive coverage of all the functions. The package has been upgraded to Tomcat 6.0 and the distribution can use Java 5.0 or 6.0.

Volunteerbase project specifications completed

Fri, 19 Oct 2007 09:33:40 GMT

With the release 0.5, the project is now covering the initial specifications. The next big steps will be the functional tests, acceptance test and the documentation. The test by the new SPW Australia team should add some new ideas and further evolutions.

Release 0.4 of VolunteerBase project

Thu, 04 Oct 2007 09:13:19 GMT

After a long iteration, finally the 0.4 is published.

The biggest challenge was to include a reporting capability without using heavy weight framework. After some issues with JPA and iReport, I have decided to choose a simpler and well known solution with Apache Fop. The idea of xsl-format looks good. It uses the css style and is able to generate many output (html, pdf, png, RTF etc...). It's really handful to separate the content of the presentation and it gives the possibility to customize easily the report. However it's not very efficient to create rapid report with complex structure. Associated with a lack of tools and the future css3, I not sure of the future of this product.

The release contains also a bunch of bug fixes.

The new function is the volunteer contribution management. The features are:

A schedule to define the payment plan for a year, depending of the month of selection
Book keeping of the volunteer contributions

The next feature in 0.5 will be an individual report to give a situation of the volunteer contributions.

Volunteer Base release 0.3

Wed, 22 Aug 2007 11:23:41 GMT

This release is mainly focused on usability improvements. The iterations will deliver alternatively new functions and defect fixes. The goal is to move from a prototype (release 0.1) to a production ready software with all the functions required in version 1.0.

This release includes work from Sean Melody, a new active and motivated contributor.

Programmatic Login from a Stand-Alone Client

Wed, 08 Aug 2007 09:18:45 GMT

This blog follow the previous one "Secured EJB 3.0 Web Start Application Client".

Now, we want to access the same EJB without Java Web Start and we want to provide a user/login programmatically. We can use a class provided with GlassFish : ProgrammaticLogin.

I assume you have done and deployed the previous project. The client part of the previous Enterprise Application is not necessary, you can skip it if you have not already done the demo. We will create a totally independent project.

Create the project

Create a new project, select Java, Projects -> Java Application and click Next. Name the project ProgrammaticLogin and click finish.

Add the libraries

We need few libraries from Glassfish in order to run the project. Right click on Libraries -> Add JAR/Folder, and add the following jar files from the <GLASSFISH_INSTALL_DIR>/lib directory of your GlassFish serveur : appserv-rt.jar, j2ee.jar, appserv-ext.jar, appserv-admin.jar. These jar contain all you need to run the client.

Right click again on Libraries -> Add Project and add the EJB project Login-ejb.

Login code

You can now open the Main class and input the following code inside the main method:

ProgrammaticLogin pm = new ProgrammaticLogin();
pm.login("demo", "demo"); //user and password of a user mapped to admin role

InitialContext ctx;
try {
    ctx = new InitialContext();
    Object ref = ctx.lookup("demo.CalculatorRemote");
    CalculatorRemote calc = (CalculatorRemote) PortableRemoteObject.narrow(ref,CalculatorRemote.class);
    javax.swing.JOptionPane.showMessageDialog(null, "2 + 2 = " + calc.add(2, 2));
    javax.swing.JOptionPane.showMessageDialog(null, calc.hello("Mr Demo"));
} catch (Exception ex) {
    ex.printStackTrace();
}

Resolve the imports (Ctrl+Maj+F with NB 5, Ctrl+Maj+I with NB 6).

Run the demo

Start the application server.

Before running the client, we must set the configuration in order to obtain the correct login module. We must give the JAAS config file.

Right click on the project, select Properties -> Run.

In VM Options, add : -Djava.security.auth.login.config=D:/JavaServers/glassfish-v2-b53/lib/appclient/appclientlogin.conf

Replace D:/JavaServers/glassfish-v2-b53/ by the directory of your GlassFish serveur. Note: don't forget the - at the beginning of -Djava.sec...

Click Run, you will see the 2 messages, including the message from restricted method hello().

Note

The programmatic login can be used with Java Web Start. Just add the 2 lines in bold in the code to the previous demo and add the required libraries.

Secured EJB 3.0 and Web Start Application Client

Sun, 05 Aug 2007 12:33:26 GMT

One option of the Glassfish Server is the ability to launch a desktop client application from the server with Java Web Start. Associated with NetBeans, it's easy to create a secured application easy to distribute.

First, with NetBeans, ensure you have GlassFish server registered (see Tools -> Server Manager and add your server GlassFish or Sun Java System Application Server version 9 included in the JavaEE 5 SDK).

Create the project

Create a new project, select Enterprise, Projects -> Enterprise Application and click Next.

In window 'Name and Location', fill in the project name with Login, your GlasFish server as Sun Java System Application Server, Java version as Java EE 5 and select Create EJB Module, deselect Create Web Application Module, select Create Application Client Module. Leave the default values for the module names and press Finish.

Create the EJB

Right click on Login-ejb -> New -> Session Bean.

Set the EJB name with Calculator, package with demo, check Remote and uncheck Local. Leave stateless checked.

Create method add

In the CalculatorBean.java source, right click -> EJB Methods -> Add Business Method. Name the method 'add' with int as return type and 2 parameters a and b as int.

Replace return 0 by return a + b

Create the method hello

Repeat the same process to add a business method hello with a String a return type and a String as parameter with 'name' as parameter name.

Replace return null by return "Hello " + name;

Add security annotations

Before @Stateless, add an annotation to declare the role admin. Insert the line :

@DeclareRoles("admin")

Before the method hello, add an annotation to restrict the access of the method to the role "admin":

@RolesAllowed("admin")

The source of the EJB must look like this

package demo;

import javax.annotation.security.DeclareRoles;
import javax.annotation.security.RolesAllowed;
import javax.ejb.Stateless;

/**
*
* @author PSe
*/
@DeclareRoles("admin")
@Stateless
public class CalculatorBean implements CalculatorRemote {
    /** Creates a new instance of CalculatorBean */
    public CalculatorBean() {
    }

    public int add(final int a, final int b) {
        return a + b;
    }

    @RolesAllowed("admin")
    public String hello(final String name) {
        return "Hello " + name;
    }
}

Client code

Open the project nodes Login-app-client -> Source Package, login and double click on Main.java.

Right click in the source select Entreprise Resources -> Call Enterprise Bean and select CalculatorBean. Press OK. The line to reference the bean is automatically inserted:

@EJB
private static CalculatorRemote calculatorBean;

Add the lines below to call the methods:

javax.swing.JOptionPane.showMessageDialog(null, "2 + 2 = " + calculatorBean.add(2, 2));
javax.swing.JOptionPane.showMessageDialog(null, calculatorBean.hello("Mr admin"));

Press Alt+Maj+F to resolve the import. The source must look like:

package login;

import demo.CalculatorRemote;
import java.rmi.RemoteException;
import javax.ejb.EJB;

/**
*
* @author PSe
*/
public class Main {
    @EJB
    private static CalculatorRemote calculatorBean;
    /** Creates a new instance of Main */
    public Main() {
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        javax.swing.JOptionPane.showMessageDialog(null, "2 + 2 = " + calculatorBean.add(2, 2));
        javax.swing.JOptionPane.showMessageDialog(null, calculatorBean.hello("Mr admin"));
    }
}

Run the application

Press the Run button , the project is deployed and the client is launched. You will see the login window:

Enter any name and password, the application will fail because we need to create the users and map the role admin.

Create the users

In the Runtime tab (service with NetBeans 6), open the Servers node and right click on Sun Java System Application Server and select View Admin Console:

Your browser will open a window to log on the server. Put the admin name and password you give when installing the application server.

Select Configuration -> Security -> Realms -> file and click Manage Users. Click New to create two user, one in the group user, the other in the group admin. In my example, the user demo is in the group admin and the user user is in the group user.

Roles mapping

To map the roles, open in the project tab the Login project -> Configuration Files and double click on sun-application.xml. Click on Edit As XML and replace <sun-application/> by :

<sun-application>
<security-role-mapping>
    <role-name>user</role-name>
    <group-name>user</group-name>
</security-role-mapping>
<security-role-mapping>
    <role-name>admin</role-name>
    <group-name>admin</group-name>
</security-role-mapping>
</sun-application>

Run again the application, enter the user demo and the password, you will see two windows:

If you try again with a user outside the admin group, you will see only the first message and the application will throw an error.

Note : with NetBeans 5.5.1, I must kill the Login process after the execution. To do this, select the Runtime tab, open the Processes node, right click on Login (Run) and select Terminate Process.

Java Web Start the application

If you open the browser and use the address http://localhost:8080/Login/Login-app-client

the application will start automatically.

This conclude the demo and give a glimpse of the power of NetBeans and GlassFish. These products are easy to use, well designed, efficient and designed for enterprise solution. Associated with the power of Java EE 5 annotations, you can construct a solution without headache.

English vocabulary

Sun, 29 Jul 2007 07:49:18 GMT

Thank you Sandy for your message to notify some mistakes but I can not respond as a result of your security setting which prevent it.
I must admit that my English is still weak after seven months in Australia. Unfortunately, it could not be as good as my computer skills and my native French (Sandy guess was right, I'm French). I try to go ahead but sometimes errors happen, it is part of the learning process. I know it's important to improve my English level so I am student in night courses.
Furthermore, I can't ask people to check my writing, I'm working alone and my wife is also French. If you are ready to give me a hand, you are welcome
Last point, I agree that the missing 's' of adds was an ugly fault and I can't argue about the plural of functionality but if you look up in the Macquarie (Australia's national dictionary): functionality 1. the purpose designed to be fulfilled by a device, tool, machine, etc. 2. Computers the range of functions which an application has. Not so ugly, isn't it?

Volunteerbase project release 0.2

Sat, 28 Jul 2007 22:45:23 GMT

This version adds new functions to the product :
- new search filters and advanced search criterias
- export to merge mail / emailer to send e-mails
- reminder and actions to be completed

It also includes some code improvements and minor bug fixes.

Release 0.1 of Volunteerbase

Sun, 08 Jul 2007 21:58:39 GMT

The first release is ready. This is a typical front end system without any extra functionalities. It gives all you need to add, modify, delete, search any information, including documents. The next release is intended to add a mailer with merge capabilities, reminders, actions to be conducted, etc...

Volunteer Base project hosted on SourceForge

Wed, 06 Jun 2007 11:53:03 GMT

The volunteer project (about volunteering) wich I am developing is new hosted on SourceForge. Feel free to look the site http://volunteerbase.sourceforge.net/

First blog

Sat, 17 Mar 2007 03:36:01 GMT

Welcome to this blog.

If you are looking for an exellent project manager or/and analyst programmer, I fit the bill.
If you are looking for a free lancer or volunteer for your Information System with latest technology, stop here, I can help you.

You can find some examples of my work on www.microcode.fr or www.habitersurlacote.com