Iterate over a collection using JAXB and StAX - 6.3

Talend ESB Mediation Developer Guide

EnrichVersion
6.3
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Talend Data Fabric
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task
Design and Development
EnrichPlatform
Talend ESB

First we suppose you have JAXB objects.

For instance a list of records in a wrapper object:

import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "records")
public class Records {
    @XmlElement(required = true)
    protected List<Record> record;
 
    public List<Record> getRecord() {
        if (record == null) {
            record = new ArrayList<Record>();
        }
        return record;
    }
}

and

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlType;
 
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "record", propOrder = { "key", "value" })
public class Record {
    @XmlAttribute(required = true)
    protected String key;
 
    @XmlAttribute(required = true)
    protected String value;
 
    public String getKey() {
        return key;
    }
 
    public void setKey(String key) {
        this.key = key;
    }
 
    public String getValue() {
        return value;
    }
 
    public void setValue(String value) {
        this.value = value;
    }
}

Then you get a XML file to process:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<records>
  <record value="v0" key="0"/>
  <record value="v1" key="1"/>
  <record value="v2" key="2"/>
  <record value="v3" key="3"/>
  <record value="v4" key="4"/>
  <record value="v5" key="5"/>
</record>

The StAX component provides an StAXBuilder which can be used when iterating XML elements with the Camel Splitter

from("file:target/in")
    .split(stax(Record.class)).streaming()
        .to("mock:records");

Where stax is a static method on org.apache.camel.component.stax.StAXBuilder which you can static import in the Java code. The stax builder is by default namespace aware on the XMLReader it uses. From Camel 2.11.1 onwards you can turn this off by setting the boolean parameter to false, as shown below:

from("file:target/in")
    .split(stax(Record.class, false)).streaming()
        .to("mock:records");

The previous example with XML DSL

The example above could be implemented as follows in XML DSL

<!-- use STaXBuilder to create the expression we want to use in the route below for 
splitting the XML file -->
<!-- notice we use the factory-method to define the stax method, and to pass in the 
parameter as a constructor-arg -->
<bean id="staxRecord" class="org.apache.camel.component.stax.StAXBuilder" factory-
method="stax">
  <!-- FQN class name of the POJO with the JAXB annotations -->
  <constructor-arg index="0" value="org.apache.camel.component.stax.model.Record"/>
</bean>
 
<camelContext xmlns="http://camel.apache.org/schema/spring">
  <route>
    <!-- pickup XML files -->
    <from uri="file:target/in"/>
    <split streaming="true">
      <!-- split the file using StAX (ref to bean above) -->
      <!-- and use streaming mode in the splitter -->
      <ref>staxRecord</ref>
      <!-- and send each splitted to a mock endpoint, which will be a Record POJO 
      instance -->
      <to uri="mock:records"/>
    </split>
  </route>
</camelContext>0