This is a simple Java library to parse AppData files. It is used in linux-store-backend

• Create a new maven project

  • IntelliJ > File > New > Project
  • Maven > Create from archetype: org.apache.maven.archetypes:maven-archetype-quickstart
    • GroupID: org.freedesktop.appstream
    • ArtifactID: appstream-appdata

• Create an example App Data file xds/appstream-seed.xml

  • It contains an example component with most of the appstream spec.
  • It's added twice in the file on purpose to tell the system that we'll have a list of components.

• IntelliJ > Select xds/appstream-seed.xml > Generate XSD schema from XML file:

  • Result schema file name: appstream.xsd
  • Design type: local elements/types
  • Detect simple content type: smart

• Rename obtained file appstream-seed.xml1.xsd to appstream-lang.xsd

• Edit xds/appstream.xsd

  • Import appstream-lang.xsd

  <?xml version="1.0" encoding="UTF-8"?>
  <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="https://www.w3.org/2001/XMLSchema">
    <xs:import namespace="https://www.w3.org/XML/1998/namespace"
      schemaLocation="appstream-lang.xsd"/>
  

  • Manually modify "description" type

  # Before
  <xs:element name="description">
    <xs:complexType>
      <xs:choice maxOccurs="unbounded" minOccurs="0">
        <xs:element ref="p"/>
        <xs:element ref="ul"/>
        <xs:element ref="ol"/>
      </xs:choice>
      <xs:attribute ref="xml:lang"/>
    </xs:complexType>
  </xs:element>
  
  # After
  <!-- We manually modify description type to allow mixed content -->
  <xs:complexType name="description" mixed="true">
    <xs:sequence>
      <xs:element name="p" type="xs:string" maxOccurs="unbounded" minOccurs="0"/>
      <xs:element ref="ul"  minOccurs="0"/>
      <xs:element ref="ol"  minOccurs="0"/>
    </xs:sequence>
    <xs:attribute ref="xml:lang"/>
  </xs:complexType>
  
  <xs:element name="description" type="description"/>
  

• Create bindings using xcj:

  cd ROOT_OF_THE_PROJECT
  xjc -d src/main/java/ -p org.freedesktop.appstream.appdata xsd/appstream.xsd 

mvn install