Using log4j 2 in an Oracle ADF 12c Application

Configure ADF12c application to work with log4j2

One of our customers had the requirement to use log4j 2 in his ADF 12c application. When executing his code

[code language=“java“]import java.io.Serializable;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import javax.faces.event.ActionEvent;
import oracle.adf.view.rich.component.rich.input.RichInputText;

public class LoggingBean implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger log = LogManager.getLogger(LoggingBean.class.getName());

public LoggingBean() {
}

public void logText(ActionEvent actionEvent) {
log.info(„Text to log“);
}

}
[/code]

an UnsupportedOperationException was thrown.

[code language=“xml“][…] Caused by: java.lang.UnsupportedOperationException: setXIncludeAware
is not supported on this JAXP implementation or earlier:
class oracle.xml.jaxp.JXDocumentBuilderFactory
at javax.xml.parsers.DocumentBuilderFactory.setXIncludeAware(DocumentBuilderFactory.java:614)
[/code]

To resolve this issue you can configure your ADF12c application to use a specific implementation of DocumentBuilderFactory. This is quite simple and straightforward. Just configure your weblogic specific deployment descriptor tor use com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl as application’s DocumentBuilderFactory implementation. This is what worked for us. Other implementations of DocumentBuilderFactory might be a valid, too. To configure the DocumentBuilderFactory you can use JDeveloper tooling:

This will put the following lines into your weblogic-application.xml:

[code language=“xml“]

com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl

[/code]

To dodge possible other unsupported operations, we also provided values for SAX Parser Factory and Transformer Factory:

• SAX Parser Factory: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
• Transformer Factory: com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl

The screenshot below shows our configuration:

Prerequisites

The following JARs have been added to project’s classpath:

• log4j-api-2.1.jar
• log4j-core-2.1.jar
• log4j-web-2.1.jar

These files are contained within the log4j2 download package.

Follow ups

Without providing any configuration file log4j2 will log our messages on console. To configure another behavior just put a configuration file into your project’s src directory (e.g. /Model/src or /ViewController/src).  The  configuration file itself can be written in XML, JSON, or YAML. For more information on the expected syntax have a look at log4j2’s official documentation.