[CONF] Apache Camel > StAX

confluence Tue, 22 Nov 2011 09:19:26 -0800

     StAX
    Page edited by             Claus Ibsen
    
        

                         Changes (17)
                                 
    

                    
    
            h2. StAX Component 

            *Available as of Camel 2.9* 

             
The StAX component allows messages to be process through a SAX [ContentHandler|http://download.oracle.com/javase/6/docs/api/org/xml/sax/ContentHandler.html]. 

            The implementation convert a SAX ContentHanler to a XMLStreamReader. 

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

             

            Another great feature of this component is to allow to iterate over JAXB records using StAX. 
 

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

            ...

            {code} 
 

            h3. Converter 
 
Some converters are provided by the component. 
 
It allows you to convert a GenericFile or a File to a SAXSource, and a GenericFile or a String (representing a file path) to either a XMLStreamReader or a XMLEventReader. 
 

            h3. Usage of a content handler as StAX parser 
 

            ...

            {code:java} 
from("file:target/in") 

              .to("stax:org.superbiz.handler.CountingHandler")  

            .to("StAX:org.superbiz.handler.CountingHandler") // CountingHandler implements org.xml.sax.ContentHandler or extends org.xml.sax.helpers.DefaultHandler 

              .process(new Processor() { 

                @Override 

            @Override public void process(Exchange exchange) throws Exception { 

                    CountingHandler handler = exchange.getIn().getBody(CountingHandler.class); 
        // do some great work with the handler 

            ...

            {code} 
 

            The StAX component provides an iterator call org.apache.camel.stax.StAXJAXBIteratorExpression which allows you 
to iterate through this collection with the camel splitter: 

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

             
{code:java} 
from("file:target/in") 

            .setBody(header(Exchange.FILE_PATH)) .split(stax(Record.class)).streaming() 

                  .split(new StAXJAXBIteratorExpression<Record>(Record.class)) 

                    .to("mock:records"); 

            {code} 
 

            The body will be the constructor parameter class (Record in the snippet). 

            Where {{stax}} is a static method on {{org.apache.camel.component.stax.StAXBuilder}} which you can static import in the Java code. 

             

            Note: depending on the first component you use to get your xml tree you can need to force the convertion of your body 
to a known format (SAXSource, XMLStreamReader, ...) to avoid to read all the file (which is implicitely the default). 

            h4. The previous example with XML DSL 
The example above could be implemented as follows in XML DSL 
 
{snippet:id=e1|lang=xml|url="" 
 
 
{include:Endpoint See Also} 

    
            
    
                            Full Content
                    
        StAX Component
Available as of 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



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 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>
      <!-- split the file using StAX (ref to bean above) -->
      <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>




See Also

	Configuring Camel
	Component
	Endpoint
	Getting Started


    
        
        
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 h2. StAX Component
+*Available as of Camel 2.9*
 The StAX component allows messages to be process through a SAX [ContentHandler|http://download.oracle.com/javase/6/docs/api/org/xml/sax/ContentHandler.html].
-The implementation convert a SAX ContentHanler to a XMLStreamReader.
+Another feature of this component is to allow to iterate over JAXB records using StAX, for example using the [Splitter] EIP.
-Another great feature of this component is to allow to iterate over JAXB records using StAX.
 Maven users will need to add the following dependency to their {{pom.xml}} for this component: 
{code:xml}
 ...
 {code}
-h3. Converter 
 
Some converters are provided by the component. 
 
It allows you to convert a GenericFile or a File to a SAXSource, and a GenericFile or a String (representing a file path) to either a XMLStreamReader or a XMLEventReader.
 h3. Usage of a content handler as StAX parser
 ...
 {code:java} 
from("file:target/in")
+  .to("stax:org.superbiz.handler.CountingHandler")
 .to("StAX:org.superbiz.handler.CountingHandler") // CountingHandler implements org.xml.sax.ContentHandler or extends org.xml.sax.helpers.DefaultHandler
   .process(new Processor() {
+    @Override
 @Override public void process(Exchange exchange) throws Exception {
         CountingHandler handler = exchange.getIn().getBody(CountingHandler.class); 
        // do some great work with the handler
 ...
 {code}
-The StAX component provides an iterator call org.apache.camel.stax.StAXJAXBIteratorExpression which allows you 
to iterate through this collection with the camel splitter:
+The StAX component provides an {{StAXBuilder}} which can be used when iterating XML elements with the Camel [Splitter]
 {code:java} 
from("file:target/in")
 .setBody(header(Exchange.FILE_PATH)) .split(stax(Record.class)).streaming()
-      .split(new StAXJAXBIteratorExpression<Record>(Record.class))
         .to("mock:records");
 {code}
-The body will be the constructor parameter class (Record in the snippet).
+Where {{stax}} is a static method on {{org.apache.camel.component.stax.StAXBuilder}} which you can static import in the Java code.
-Note: depending on the first component you use to get your xml tree you can need to force the convertion of your body 
to a known format (SAXSource, XMLStreamReader, ...) to avoid to read all the file (which is implicitely the default).
+h4. The previous example with XML DSL 
The example above could be implemented as follows in XML DSL 
 
{snippet:id=e1|lang=xml|url="" 
 
 
{include:Endpoint See Also}

[CONF] Apache Camel > StAX

StAX

Page edited by Claus Ibsen

Changes (17)

Full Content

StAX Component

URI format

Usage of a content handler as StAX parser

Iterate over a collection using JAXB and StAX

The previous example with XML DSL

See Also

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