I am trying to work out how to unmarshall and XML document to a Java document.
The top of the xml document looks like this
<xs:myData xmlns:xs="http://www.example.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.com example.xsd ">
There is a schema file whose top section looks like this:
<schema targetNamespace="http://www.example.com"
elementFormDefault="qualified"
xmlns="http://www.w3.org/2001/XMLSchema"
xmlns:xs="http://www.example.com">
I would like to unmarshall the xml document using Spring/JaxB and eventually convert it to a JPA object. I am not sure how to go about so i looked for examples on google and came up with this http://thoughtforge.net/610/marshalling-xml-with-spring-ws-and-jaxb/
I understand most of it except how or where the schema is used.
I have seen other examples where the schema is explicitly specified, i.e.
SchemaFactory schemaFac = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema sysConfigSchema = schemaFac.newSchema(
new File("example.xsd"));
unmarshaller.setSchema(sysConfigSchema);
RootElement root = (RootElement)unmarshaller.unmarshal(
new File("example1.xml"));
How is the schema shown in the first link used to validate the xml document?
Are there any disadvantages to using Spring's jaxb2Marshaller as opposed to direct use of JAXB?
What is the effect of having the namespace next to the XmlElement annotation? (See the Person class)
I would appreciate any more examples showing Spring/REST with unmarshalling with schema validation.
Thanks
As far as I know JAXB does not parse xsi attribute to dereference XSD, load it and use for validation. Perhaps that was done to disable automatic validation, otherwise it would be problematic to switch it off :)
Spring Jaxb2Marshaller was obviously added to implement the same interface org.springframework.oxm.Marshaller (which is implemented also by CastorMarshaller, JibxMarshaller, ...). It is very powerful and allows you to tune JAXBContext in very flexible way (I can't imagine the scenario when provided API is not enough). From pattern point of new Jaxb2Marshaller is a builder, so it does not add anything to core JAXB functionality. But there are some evident advantages. For example, schema loading is very simple. In the article the Spring context refers the person.xsd (<property name="schema" value="classpath:schema/person.xsd"/>) which one need to put into resources explicitly. Then JAXB marshaller/unmarshaller will use this schema to validate XML when XML is generated/loaded.
#XmlElement(..., namepsace="xxx") will automatically generate this XML element with a specified namespace. It's rare case if somebody does not use namespaces. I would say writing XSD without namespaces is not normal, as you want to avoid the element name collision.
Using JAXB with RestTemplate is very simple. You need to be sure that JAXB runtime is in your classpath (JDK 6 already has it) and your bean is annotated with #XmlRootElement. Then just use Person person = restTemplate.getForObject(restServiceUrl, Person.class),
Related
I am new about jaxb. My question is the following: using jaxb, is it possible to do automatic mapping from an xml file to a java object?
Starting from xml file, is there something generate the Java class with annotations jaxb relaitve?
It is indeed possible. However, you'll need an XSD rather than an XML file. There are tools out there (Trang, for instance) that can infer an XSD from one or more example XML files.
Take into account that generating this XSD with a tool might get you inaccurate results if the XML sample isn't complete, or if the schema can't be fully represented in a single XML file (exclusive elements, etc).
Once you have an XSD, use xjc in order to generate the marshaller/unmarshaller classes.
xjc myxsd.xsd
This will generate the annotated classes that JAXB will use for marshalling/unmarshalling. Notice you could also have coded these classes yourself. Once you have them, just use them in your code:
File file = new File("myFile.xml");
JAXBContext jaxbContext = JAXBContext.newInstance(MyRootElement.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
MyRootElement element = (MyRootElement) jaxbUnmarshaller.unmarshal(file);
Yes, JAXB automatically does marshalling and unmarshalling but it requires a schema file.
JaxB is used to bind XML with Java objects. Using the XSD schema file, it does marshalling and unmarshalling. There are few simple ant tasks like XJC that can be used.
i have a fully annotated class and multiple xsds(each with a different set of fields)
and i wish to marshal according to the different xsds using the same class.
i would like to be able to control the marshaling/unmarshaling process and filter out some fields according to the xsd.
btw i am using cxf.
thanks,
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.
If you use MOXy as your JAXB provider then you could have the model mapped to one XML schema via the standard annotations, and then adjust the mappings to match the other XML schemas using MOXy's external mapping document (see: http://blog.bdoughan.com/2010/12/extending-jaxb-representing-annotations.html).
JAXBContext #1 - Created based on annotations to match schema #1
JAXBContext #2 - Created based on annotations and mapping file #1 to match schema #2
JAXBContext #3 - Created based on annotations and mapping file #2 to match schema #3
The mapping file also allows you to have the annotations completely ignored if one of your schemas bares little resemblance to the others.
http://blog.bdoughan.com/2011/09/mapping-objects-to-multiple-xml-schemas.html
We're facing an issue when marshalling an object to xml with JAXB. In our code example (https://github.com/fbe/JaxbIssueTracker, simple maven project, test-case demonstrates what's going wrong) we have three types:
parent
hijacked
concrete
XSDs can be found here: github
The parent type is abstract, concrete extends the parent, parent references the hijacked type in a sequence. From these xsd-files the JAVA files are being generated by JAXB (xjc) without any warn- or error-messages.
When marshalling a concrete type the following xml-output is being generated by JAXB:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns3:concreteType xmlns:ns2="http://www.felixbecker.name/parent" xmlns="http://www.felixbecker.name/hijacked" xmlns:ns3="http://www.felixbecker.name/concrete">
<ns2:hijacked>
<value>foobar</value>
</ns2:hijacked>
</ns3:concreteType>
As you can see the hijacked-type is falsely using the ns2-prefix which refers to the namespace of the parent type - but instead it should use the default namespace which refers to the hijacked namespace.
JAXB is not able to unmarshal this generated xml although it is generated by itself with activated schema validation.
What is going wrong here? Is the xml-schema broken? Or is JAXB not able to deal with inheritance correctly?
Removing the abstract-attribute from the parent.xsd did not have any effect on the faced issue.
Any help would be highly appreciated! :-)
Used versions (both broken):
JAXB from JDK 1.6
JAXB-RI 2.2.5
Regards,
fbe & ollinux
In your example, the hijacked element is actually defined in the parent schema and so gets placed in the "parent" namespace. This means the namespaces of the marshalled document are correct. If jaxb can unmarshal the document it itself marshalled then this sounds like a bug to me.
To get the hijacked element in the correct namespace you could move the element declaration to the hijacked schema and use
<element ref="hijacked:hijacked"/>
in the parent schema.
I have an XML content without defined attributes, like this:
<rootElement>
<subElement1/>
</rootElement>
I want to populate this XML content with required attributes defined in XML Schema (XSD) for this XML.
For example, according to XSD subElement1 has required attribute 'id'.
What is the best way (for Java processing) to detect that and add such attributes to XML?
We need to add required attributes and set appropriate values for them.
As a result for example above we need to have the following XML:
<rootElement>
<subElement1 id="some-value"/>
</rootElement>
In the XML schema definition, i.e. XSD file, attributes are optional by default. To make an attribute required, you have to define:
<xs:attribute name="surname" type="xs:string" use="required"/>
You will find a very good introduction on XML and XML Schema Definitions, i.e. XSD, on W3 Schools.
In Java the equivalent of defining a XML schema is using JAXB, i.e. Java API for XML Binding that is included into Java SE. There you would define, e.g.
#XmlRootElement
public class Person { public #XmlAttribute(required=true) String surname; }
Hope this could clarify your question.
I would suggest you to use JAXB for that. Search the Internet for tutorials.
Steps to proceed further with JAXB,
Generate Java files using JAXB by providing the schema
Unmarshal your XML to generated Java classes (beans). Don't do validation or set validation handler here.
Populate those classes with appropriate values. required elements can be found using annotation look up. JAXB annotation for element would look like something, #XmlElement(name = "ElementName", required = true). And an attribute annotation would be something similar to this, #XmlAttribute(required = true)
Marshal your bean back to XML. You can validate your bean using ValidationHandler, while marshalling. Below is the sample code snippet,
marshller = JAXBContext.newInstance(pkgOrClassName).createUnmarshaller();
marshller.setSchema(getSchema(xsd)); // skip this line for unmarshaller
marshller.setEventHandler(new ValidationHandler()); // skip this line for unmarshaller
Use a DOM parser.Has methods to traverse XML trees, access, insert, and delete nodes
I have had the same idea of Cris but I think that with this validator you don't have information about the point in which you have had the error.
I think that you have to create or extend your own validator.
I am creating amazon feed, the feed xml should be like:
<AmazonEnvelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="amzn-envelope.xsd">
I am using jaxb to generate xml files from java classes, I used NamespacePrefixMapperImpl from jaxb samples to add namespaces to the xml. But currently it generates the root like:
<AmazonEnvelope xmlns:xsi:noNamespaceSchemaLocation="amzn-envelope.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
how I can remove the xmlns from amzn-envelope.xsd??
Here's the mapping I used in NamespacePrefixMapperImpl
if( "http://www.w3.org/2001/XMLSchema-instance".equals(namespaceUri) )
return "xsi";
if("amzn-envelope.xsd".equals(namespaceUri))
return "xsi:noNamespaceSchemaLocation";
I found a property at Marshaller that can add the amzn-envelope.xsd:
marshaller.setProperty("jaxb.noNamespaceSchemaLocation", "amzn-envelope.xsd");
and left the NamespacePrefixMapper to add the "http://www.w3.org/2001/XMLSchema-instance".
Hope this helps others.
If I understand your intent, your document has a default namespace, and you're trying to add the schemalLocation for that namespace.
NamespacePrefixMapper won't let you do this, it's useful only for picking a prefix for a namespace. There are no namespaces in this document, and so no useful way of using NamespacePrefixMapper. It can't be used for adding schemaLocation hints - those are treated specially by JAXB, and you're just confusing it.
Are you sure you need the noNamespaceSchemaLocation="amzn-envelope.xsd" at all? Have you tried sending it to the web service without it?