Generate Java classes from XSD files

Question

I have a gigantic QuickBooks SDK  XSD schema file which defines XML requests responses that I can send receive from QuickBooks   I d like to be able to easily generate Java classes from these  XSD files  which I could then use to marshal XML to Java objects  and Java objects to XML    Is there an easy way to do this       Ideally  it would not require any libraries external to the basic Java distro at run-time  But I m flexible

User · Accepted Answer

JAXB does EXACTLY what you want  It s built into the JRE JDK starting at 1 6

User · Answer

Isn t JAXB s XJC is a possible answer to this  I m trying to achieve the same thing  Still in the  trying  phase though  Came across XJC  so thought of sharing

User · Answer

JAXB Limitation   I worked on JAXB  as per my opinion its a nice way of dealing with data between XML and Java objects  The Positive sides are its proven and better in performance and control over the data during runtime  With a good usage of built tools or scripts it will takes away lot of coding efforts   I found the configuration part is not a straight away task  and spent hours in getting the development environment setup   However I dropped this solution due to a silly limitation I faced  My XML Schema Definition   XSD   has a attribute element with name  value  and that I have to use XSD as it is  This very little constraint forced the  my binding step XJC failed with a Error  Property  Value  already used    This is due to the JAXB implementation  the binding process tries to create Java objects out of XSD by adding few attributes to each class and one of them being a value attribute  When it processed my XSD it complained that there is already a property with that name

User · Answer

XMLBeans will do it   Specifically the  scomp  command   EDIT  XMLBeans has been retired  check this stackoverflow post for more info

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If you want to start coding Java to XML and XML to Java in less than 5 minutes  try  Simple XML Serialization   Don t spend hours learning the JAXB API  http   simple sourceforge net download stream doc tutorial tutorial php However  if you are really keen on learning JAXB  here s an excellent tutorial http   blogs oracle com teera entry jaxb for simple java xml Contents of tutorial  JAXB for simple Java-XML serialization There re a number of way to do XML serialization in Java  If you want fine-grained control over parsing and serialization you can go for SAX  DOM  or Stax for better performance  Yet  what I often want to do is a simple mapping between POJOs and XML  However  creating Java classes to do XML event parsing manually is not trivial  I recently found JAXB to be a quick and convenient Java-XML mapping or serialization  JAXB contains a lot of useful features  you can check out the reference implementation here  Kohsuke s Blog is also a good resource to learn more about JAXB  For this blog entry  I ll show you how to do a simple Java-XML serialization with JAXB  POJO to XML Let s say I have an Item Java object  I want to serialize an Item object to XML format  What I have to do first is to annotate this POJO with a few XML annotation from javax xml bind annotation   package  See code listing 1 for Item java From the code   XmlRootElement name  quot Item quot   indicates that I want  to be the root element   XmlType propOrder     quot name quot    quot price quot    indicates the order that I want the element to be arranged in XML output   XmlAttribute name  quot id quot        indicates that id is an attribute to  root element   XmlElement       indicates that I want price and name to be element within Item   My Item java is ready  I can then go ahead and create JAXB script for marshaling Item    creating Item data object Item item   new Item    item setId 2   item setName  quot Foo quot    item setPrice 200          JAXBContext context   JAXBContext newInstance item getClass     Marshaller marshaller   context createMarshaller      I want to save the output file to item xml marshaller marshal item  new FileWriter  quot item xml quot      For complete code Listing please see Code Listing 2 main java  The output Code Listing 3 item xml file is created  It looks like this   lt  xml version  quot 1 0 quot  encoding  quot UTF-8 quot  standalone  quot yes quot   gt   lt ns1 item ns1 id  quot 2 quot  xmlns ns1  quot http   blogs sun com teera ns item quot  gt     lt ns1 itemName gt Foo lt  ns1 itemName gt     lt ns1 price gt 200 lt  ns1 price gt   lt  ns1 item gt   Easy right  You can alternatively channel the output XML as text String  Stream  Writer  ContentHandler  etc by simply change the parameter of the marshal      method like     JAXBContext context   JAXBContext newInstance item getClass     Marshaller marshaller   context createMarshaller       save xml output to the OutputStream instance marshaller marshal item   lt java io OutputStream instance gt         JAXBContext context   JAXBContext newInstance item getClass     Marshaller marshaller   context createMarshaller    StringWriter sw   new StringWriter      save to StringWriter  you can then call sw toString   to get java lang String marshaller marshal item  sw    XML to POJO Let s reverse the process  Assume that I now have a piece of XML string data and I want to turn it into Item java object  XML data  Code listing 3  looks like  lt  xml version  quot 1 0 quot  encoding  quot UTF-8 quot  standalone  quot yes quot   gt   lt ns1 item ns1 id  quot 2 quot  xmlns ns1  quot http   blogs sun com teera ns item quot  gt     lt ns1 itemName gt Bar lt  ns1 itemName gt     lt ns1 price gt 80 lt  ns1 price gt   lt  ns1 item gt   I can then unmarshal this xml code to Item object by     ByteArrayInputStream xmlContentBytes   new ByteArrayInputStream  xmlContent getBytes     JAXBContext context   JAXBContext newInstance Item getClass     Unmarshaller unmarshaller   context createUnmarshaller      note  setting schema to null will turn validator off unmarshaller setSchema null   Object xmlObject   Item getClass   cast unmarshaller unmarshal xmlContentBytes    return xmlObject       For complete code Listing please see Code Listing 2  main java   The XML source can come in many forms both from Stream and file  The only difference  again  is the method parameter      unmarshaller unmarshal new File  quot Item xml quot        reading from file        inputStream is an instance of java io InputStream  reading from stream unmarshaller unmarshal inputStream    Validation with XML Schema Last thing I want to mention here is validating input XML with schema before unmarshalling to Java object  I create an XML schema file called item xsd  For complete code Listing please see Code Listing 4  Item xsd   Now what I have to do is register this schema for validation      Schema schema   SchemaFactory newInstance XMLConstants W3C XML SCHEMA NS URI   newSchema new File  quot Item xsd quot     unmarshaller setSchema schema     register item xsd shcema for validation      When I try to unmarshal XML data to POJO  if the input XML is not conformed to the schema  exception will be caught  For complete code Listing please see Code Listing 5  invalid item xml   javax xml bind UnmarshalException - with linked exception  javax xml bind JAXBException caught  null  org xml sax SAXParseException  cvc-datatype-valid 1 2 1   item1  is                                 not a valid value for  integer     Here I change the  id  attribute to string instead of integer  If XML input is valid against the schema  the XML data will be unmarshalled to Item java object successfully

User · Answer

To expand on the  use JAXB  comments above    In Windows       java home  bin xjc  -p  your namespace   xsd file  xsd  e g          java home  bin xjc  -p com mycompany quickbooks obj quickbooks xsd  Wait a bit  and if you had a well-formed XSD file  you will get some well-formed Java classes

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If you don t mind using an external library  I ve used Castor to do this in the past

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Using Eclipse IDE -   copy the xsd into a new existing project  Make sure you have JAXB required JARs in you classpath  You can download one here  Right click on the XSD file -  Generate -  JAXB classes

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the easiest way is using command line  Just type in directory of your  xsd file    xjc myFile xsd    So  the java will generate all Pojos

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The well-known JAXB  There is a maven plugin that could do this for you at any build phase you want   You could do this stuff in both ways  xsd  lt -  Java

User · Answer

Well best option is  java home  bin xjc -p  your namespace   xsd file  xsd   I also have a question if we have an option to do reverse engineering here  if yes can we generate xsd from pojo class

User · Answer

Maven can be used for the purpose  you need to add some dependencies and just clean your application  You will get all classes created automatically in your target folder  Just copy them from target to desired place  here is pom xml that I have used to create classed from xsd files   lt plugin gt       lt groupId gt org codehaus mojo lt  groupId gt       lt artifactId gt jaxb2-maven-plugin lt  artifactId gt        lt executions gt           lt execution gt               lt goals gt                   lt goal gt xjc lt  goal gt               lt  goals gt           lt  execution gt       lt  executions gt       lt configuration gt           lt schemaDirectory gt src main webapp schemas  lt  schemaDirectory gt       lt  configuration gt   lt  plugin gt   Just place your xsd files under src main webapp schemas  and maven will find them at compile time  Hope this will help you  more information can be found at http   www beingjavaguys com 2013 04 create-spring-web-services-using-maven html

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Talking about JAXB limitation  a solution when having the same name for different attributes is adding inline jaxb customizations to the xsd                                     binding declarations                       or external customizations     You can see further informations on   http   jaxb java net tutorial section 5 3-Overriding-Names html

[java] Generate Java classes from .XSD files...?

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