JAXB 面试题与答案

Question: How to generate Java from XML Schema. Please show the example.

Answer: • From command-line
– Windows: %JAXB_HOME%binxjc cars.xsd
– UNIX: %JAXB_HOME%/bin/xjc.sh cars.xsd
– these write generated files to current directory
• From Ant
<java jar="${env.JAXB_HOME}/lib/jaxb-xjc.jar" fork="yes">
<arg line="-d ${gen.src.dir} cars.xsd"/>
</java>

Generated Files:

• com/withoutbook/cars directory
– Car.java
• interface representing the “car” complex type
• only describes get and set methods for car properties
– Cars.java
• interface representing “cars” global element
• extends CarsType and javax.xml.bind.Element (just a marker interface)
• describes no additional methods
– CarsType.java
• interface representing anonymous complex type
defined inside the “cars” global element
• provides method to get collection of Car objects (as a java.util.List)
– ObjectFactory.java
• class used to create objects of the above interface types
• extends DefaultJAXBContextImpl which extends JAXBContext
– bgm.ser
• a serialized object of type com.sun.msv.grammar.trex.TREXGrammar
• can’t find any documentation on this - don’t know its purpose
– jaxb.properties
• sets a property that defines the class used to create JAXBContext objects

• com/withoutbook/cars/impl directory
– CarImpl.java
• class that implements Car
• corresponds to the “car” XML Schema complexType
– CarsTypeImpl.java
• class that implements CarType
• corresponds to the XML Schema anonymous type inside the “cars” element
– CarsImpl.java
• class that extends CarsTypeImpl and implements Cars
• corresponds to the “cars” XML Schema element