StAX

Since Camel 2.9

The StAX component allows messages to be process through a SAX ContentHandler.

Another feature of this component is to allow to iterate over JAXB records using StAX, for example using the Splitter EIP.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-stax</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

stax:content-handler-class

example:

stax:org.superbiz.FooContentHandler

From Camel 2.11.1 onwards you can lookup a org.xml.sax.ContentHandler bean from the Registry using the # syntax as shown:

stax:#myHandler

Options

The StAX component has no options.

The StAX endpoint is configured using URI syntax:

stax:contentHandlerClass

with the following path and query parameters:

Path Parameters (1 parameters):

Name Description Default Type

contentHandlerClass

Required The FQN class name for the ContentHandler implementation to use.

String

Query Parameters (1 parameters):

Name Description Default Type

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-stax-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 2 options, which are listed below.

Name Description Default Type

camel.component.stax.enabled

Enable stax component

true

Boolean

camel.component.stax.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

Usage of a content handler as StAX parser

The message body after the handling is the handler itself.

Here an example:

from("file:target/in")
  .to("stax:org.superbiz.handler.CountingHandler")
  // CountingHandler implements org.xml.sax.ContentHandler or extends org.xml.sax.helpers.DefaultHandler
  .process(new Processor() {
    @Override
    public void process(Exchange exchange) throws Exception {
        CountingHandler handler = exchange.getIn().getBody(CountingHandler.class);
        // do some great work with the handler
    }
  });

Iterate over a collection using JAXB and StAX

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

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