Exception page with ADF Taskflow

ADF Taskflow gives you the option to have one exception page in every bounded and unbounded taskflow. This page which you can design yourself will handle, the not handled errors like java nullpointer exceptions. It does not overrule business rules errors like a salary to high, these exceptions are still displayed at the right place. You can now handle the white screens with the stacktrace.
In this example I made a custom exception page where the stacktrace is displayed in an textarea and added a email action so the error can be send to support.
This is how you can add a exception page to the taskflow. First create a view in the taskflow and generate a page on this view. Select the view and press the mark Exception Handler button.
This is how it looks in the taskflow. You don't have to create a control flow rules because you can have only one exception view and every not handled error is redirected to this view
Here you see that a normal error like a duplicate key is still displayed at the right place
My jsf exception page looks like this.

<af:panelFormLayout>
  <af:outputText value="Exception Occured"
                 inlineStyle="color:Red; font-size:large;"/>
<af:commandButton text="Send exception to support"
                  action="#{exception.sendMail}"/>
<af:inputText label="Message"
                value="#{controllerContext.currentViewPort.exceptionData.message}"
                rendered="#{controllerContext.currentViewPort.exceptionPresent}"
                />
  <af:inputText label="Stacktrace"
                value="#{exception.stacktrace}" rows="20"
                readOnly="true"
                rendered="#{controllerContext.currentViewPort.exceptionPresent}"
                columns="100"/>
</af:panelFormLayout>

Here is the code of the backing bean which retrieves the stacktrace of the error and send the error to support.

package nl.ordina.bean;

import java.io.PrintWriter;
import java.io.StringWriter;

import java.util.Properties;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;

import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import oracle.adf.controller.ControllerContext;

public class Exception {
    private ControllerContext cc;

    public Exception() {
        cc = ControllerContext.getInstance();
    }
    
    public String getStacktrace() {
        if ( cc.getCurrentViewPort().getExceptionData()!=null ) {
            StringWriter sw = new StringWriter();
            PrintWriter pw = new PrintWriter(sw); 
            cc.getCurrentViewPort().getExceptionData().printStackTrace(pw); 
            return sw.toString();            
        }
        return null;
    }
    

    public String sendMail()
    {
      Properties p = System.getProperties();
      p.put("mail.transport.protocol","smtp");
      p.put("mail.smtp.host","smtp.xs4all.nl");

      Session session = Session.getInstance(p);
      MimeMessage message = new MimeMessage(session);
      try {
            message.setFrom(new InternetAddress("xxxx@xxxx.nl"));
            message.addRecipient(Message.RecipientType.TO,new InternetAddress("xxxx@xxxxx.nl"));
            message.setSubject(cc.getCurrentViewPort().getExceptionData().getMessage());
            message.setContent(getStacktrace(),"text/plain");
            Transport.send(message);
        } catch (MessagingException e) {
            // TODO
           e.printStackTrace();
      }
      System.out.println(message.toString());
      return null;
    }
    
}