Java: Binding the XML Schema itself to classes - java

i know that you can generate Java classes from an XSD file with JAXB or similar methods and then use them with your resulting XML files. That's not what i'm looking for though.
I was wondering if it is possible to generate a generic Java representation of the XSD itself and if there are programs that parse any random XSD and fill the Java classes with it.
For example, let's take this short excerpt from an XSD:
<xs:complexType name="pc-type">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="manufacturer" type="xs:string"/>
</xs:sequence>
<xs:attribute name="id" type="xs:integer"/>
</xs:complexType>
A Java representation could be something like:
public class ComplexType{
String name;
List<Attribute> attributes;
List<Element> elements;
...
}
Does something like this exist?

There is a XSD for XSD. You can generate the JAXB classes from this xsd.xsd.

Related

Declare collection of varying types in XSD

I have an API that returns an XML set of objects, these objects are guaranteed to be representable by an abstract class, however they are not directly accessible as a list since they take the following form:
<Response Timestamp="2019-02-06T13:16:32">
<TypeA [xml attributes]...>
...
</TypeA>
<TypeB ...>
...
</TypeB>
... (Different repeating elements)
</Response>
Due to company practices I am to write the model for this feed using an XSD, which is parsed by JaxB to generate the source files. However, short of individually declaring the Types as possible elements of the collection (which I do not want to do for obvious reasons), I do not know how to approach this and get the child elements of the response as one single collection.
XSD for the response.
<xs:complexType name="Response">
<xs:sequence>
<xs:element name="Types" type="model:AbstractType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
Example element type
public class TypeA extends AbstractType
{
//Generated source
}
How do I designate in the XSD that any TypeX object, extending AbstractType, should go in to the Types collection from the response?
Happy to provide any necessary further information, as long as it is not something I am not allowed to share.
Saw this related question however it accepted any element, and the restriction was based on name, whereas for this I would ideally like to validate that the elements collected are valid TypeX objects.
Assuming you have defined each TypeX as AbstractType extension in the XSD:
<xsd:complexType name="TypeX">
<xsd:complexContent>
<xsd:extension base="AbstractType">
...
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
Then you can do:
1) XSD choice, if you really want to use different XML element names for each TypeX (not recommended because requires to modify the Response type whenever you add a new AbstractType subtype):
<xs:complexType name="Response">
<xs:choice maxOccurs="unbounded">
<xs:element name="typeA" type="model:TypeA" />
<xs:element name="typeB" type="model:TypeB" />
</xs:sequence>
</xs:complexType>
2) XML polymorphism (close to what you suggest), more generic although changes the XML form:
<xs:complexType name="Response">
<xs:sequence>
<xs:element name="something" type="model:AbstractType" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
(Replace 'something' with some meaningful name depending on what AbstractType represents actually.)
The xml would look like this:
<Response Timestamp="2019-02-06T13:16:32" xmlns="...">
<something xsi:type="TypeA" [xml attributes]...>
...
</something>
<something xsi:type="TypeB" ...>
...
</something>
... (Different repeating elements)
</Response>
In both cases, I recommend you use JAXB RI extension for simpler/better binding mode (ยง 3.1.6), or equivalent extension, that simplifies the generated code and convert generated fields to plural form when necessary.
Then the generated code in Response class (notice the plural form):
List<AbstractType> somethings; .

mapping anyType to String in JAXB

I need to generate java classes for 3rd party schema I received (and unfortunately cannot modify), that looks like that:
...
<xs:element name="ARec">
<xs:complexType>
<xs:sequence>
<xs:element name="ARecTyp" />
<xs:element name="AGrp" />
<xs:element name="AGrpId" />
...
And using maven-jaxb2-plugin, I'm able to do that, but my classes has all them members declared as
#XmlElement(name = "ARecTyp", required = true)
protected Object aRecTyp;
(which, I believe, is correct and default mapping of xs:anyType). But in reality these elements are all texts, and I'd like to have it bound to java.lang.String, not java.lang.Object.
I tried to add
<globalBindings>
<javaType name="java.lang.String" xmlType="xs:anyType"/>
</globalBindings>
but that won't work, as xs:anyType is complexType, not simpleType, so I'm getting exception. Is there any other way of mapping such xs:element without specified type to String instead of Object?

JAXB case sensitive class generation

I want to create classes from a standard schema learning object model. The schema appears to be broken due to a lowercased type. Is there any way that I can generate classes with jaxb in a "case insensitve" mode?
Here is the problem where the conflict comes out:
<xs:complexType name="Duration">
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="duration" type="DurationValue"/>
<xs:element name="description" type="description"/>
<xs:group ref="ex:customElements"/>
</xs:choice>
</xs:complexType>
<xs:complexType name="duration">
<xs:complexContent>
<xs:extension base="Duration">
<xs:attributeGroup ref="ag:duration"/>
<xs:attributeGroup ref="ex:customAttributes"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
I have rename the "duration" tag to "customDuration" and I have change the references as well and it works.
Thank you!
I think that you should change the schema in order to have Duration and duration_, generate JAXB objects and then change your JAXB classes generated in order to adapt them to the origina WSDL. For example, in Java:
#XmlElement(name = "Duration")
protected String duration;
#XmlElement(name = "duration")
protected String duration_;
(I have simplified the types in the example). Hope anyway you find a better solution.
This was already answered but Hope this will help some one else , use -XautoNameResolution so that new classes will be generated whenever it encounters two elements with same name (Case insensitive). I used it as following
xjc -d src -p com.sample -wsdl somewsdl.wsdl -XautoNameResolution

Convert XSD to tree structure with Java

I want to generate documentation for XML schemas.
My goal is to analyze the xsd file and to display it as a tree structure (with all complex / anonymous types resolved). Furthermore I need to annotate all items in that tree with their cardinality (as defined by the schema).
The following small example might help to clarify my problem.
a) the xsd file:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="client" type="clientType" />
<xs:complexType name="clientType">
<xs:sequence minOccurs="1" maxOccurs="1">
<xs:element name="first_name"/>
<xs:element name="last_name"/>
<xs:element name="address" type="addressType"
minOccurs="1" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="addressType">
<xs:sequence>
<xs:element name="street"/>
<xs:element name="number" minOccurs="0" maxOccurs="1"/>
<xs:element name="city"/>
<xs:element name="zipcode"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
b) Output I'd like to see:
client [1]
first_name [1]
last_name [1]
address [1..n]
street [1]
number [0..1]
city [1]
zipcode [1]
Does anybody know a java based solution for this problem? Preferably based on Eclipse Schema Infoset, but I'm happy to use other libraries as well.
XSOM can normalize an XSD into a comprehensible data structure that you can loop over and print out.
Given that XSD schema are also XML you could process this as XML giving you many options for how to do this.
My preference would be to use an XSLT stylesheet with templates to match the element and complex type elements to get the output list, and further templates to match the minOccurs and maxOccurs attributes to get your cardinality.
Examples of stylsheets to do this are probably available online already.
Although not having a proper solution I would propose the following: use a tool that is capable of generating a sample XML instance based on the XSD, e.g. eclipse IDE (as it is open source it should be possible to extract the relevant code and use it within a standalone solution). This XML should be very close to the tree structure you are requiring. Then, parse the XSD and annotate the elements in the generated XML structure with the cardinalities.

Generating JAXB classes with custom class names

I have a schema which names all its elements and complexTypes in capital letters and so all my class names are also in caps.
Can you let me know how to capture this and name the classes in CamelCase?
Ex: Snippet of XSD :
<xs:element name="REGISTRATION_DATE">
<xs:complexType mixed="true">
<xs:attribute name="UNIT" />
</xs:complexType>
</xs:element>
Currently it is generating as : REGISTRATIONDATE .
But I would like to generate class as : RegistrationDate .
Regards,
Satya
There is a plugin for XJC to do this - the CamelCase Always plugin.

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