How to parse an XML file with XS (XML Schema) validation using the SAX API?

if you want to parse an XML file with XS (XML Schema) validation using the SAX API, you can follow these suggestions:

1. Set the validation flag to true on SAXParserFactory object:

      SAXParserFactory f = SAXParserFactory.newInstance();
	  f.setValidating(Boolean.parseBoolean(args[1]));

2. Turn Schema Validation on and Namespace Awareness on:

      f.setNamespaceAware(true);
	  f.setFeature("http://apache.org/xml/features/validation/schema",true);

3. Provide the XML file with XML Schema location (User.xsd) provided, UserXsdError.xml:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Copyright (c) 2017 FYIcenter.com -->
<fyi:User xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:fyi="http://fyicenter.com"
  xsi:schemaLocation="http://fyicenter.com User.xsd">
    <fyi:ID>ONE</fyi:ID>
    <fyi:Name>Frank Y. Ivy</fyi:Name>
    <fyi:BirthDate>1970-01-01+00:01</fyi:BirthDate>
    <fyi:Sex>  Male</fyi:Sex>
</fyi:User>

Here is a complete example of parsing an XML with DTD validation using SAX API, SaxXmlXsValidation.java:

// Copyright (c) 2017 FYIcenter.com
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import java.io.*;

public class SaxXmlXsValidation extends DefaultHandler {
   static String dot = "............................................................";
   static int l = 0;
   public static void main(String[] args) throws Exception {
      SAXParserFactory f = SAXParserFactory.newInstance();
      f.setNamespaceAware(true);
	  f.setValidating(Boolean.parseBoolean(args[1]));
	  f.setFeature("http://apache.org/xml/features/validation/schema",true);
      SAXParser p = f.newSAXParser();
      System.out.println("Parser class: "+p.getClass().getName());

	  p.parse(new File(args[0]), new SaxXmlXsValidation());
   }
   public void startElement(String uri, String lName, String qName, Attributes atts) {
      l++;
      System.out.print("\n"+dot.substring(0,l)+lName+qName);
   }
   public void endElement(String uri, String lName, String qName) {
      l--;
   }
   public void characters(char[] ch, int start, int length) {
      System.out.print("("+(new String(ch,start,length))+")");
   }
   public void error(SAXParseException e) throws SAXException {
      System.out.println("\nError: "+e.toString()); 
   }
}

Compile and run the example program, SaxXmlXsValidation.java:

>\fyicenter\jdk-1.8.0\bin\javac SaxXmlXsValidation.java

>\fyicenter\jdk-1.8.0\bin\java SaxXmlXsValidation UserXsdError.xml true

Parser class: com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl

.Userfyi:User
..IDfyi:ID(ONE)
Error: org.xml.sax.SAXParseException; systemId: file:UserXsdError.xml; lineNumber: 6; columnNumber: 25; 
   cvc-datatype-valid.1.2.1: 'ONE' is not a valid value for 'integer'.
Error: org.xml.sax.SAXParseException; systemId: file:UserXsdError.xml; lineNumber: 6; columnNumber: 25; 
   cvc-type.3.1.3: The value 'ONE' of element 'fyi:ID' is not valid.

..Namefyi:Name(Frank Y. Ivy)
..BirthDatefyi:BirthDate(1970-01-01+00:01)
Error: org.xml.sax.SAXParseException; systemId: file:UserXsdError.xml; lineNumber: 8; columnNumber: 52; 
   cvc-datatype-valid.1.2.1: '1970-01-01+00:01' is not a valid value for 'dateTime'.
Error: org.xml.sax.SAXParseException; systemId: file:UserXsdError.xml; lineNumber: 8; columnNumber: 52; 
   cvc-type.3.1.3: The value '1970-01-01+00:01' of element 'fyi:BirthDate' is not valid.

..Sexfyi:Sex(Male)

If you run it again with "false", you will not see any validation errors:

>\fyicenter\jdk-1.8.0\bin\java SaxXmlXsValidation UserXsdError.xml false

Parser class: com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl

.Userfyi:User
..IDfyi:ID(ONE)
..Namefyi:Name(Frank Y. Ivy)
..BirthDatefyi:BirthDate(1970-01-01+00:01)
..Sexfyi:Sex(Male)

The XML Schema file used in the above test is, User.xsd:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Copyright (c) 2017 FYIcenter.com -->
<xsd:schema
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
   xmlns:fyi="http://fyicenter.com"
   targetNamespace="http://fyicenter.com"
   elementFormDefault="qualified">

  <xsd:element name="User">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="ID" type="xsd:integer"/>
        <xsd:element name="Name" type="xsd:string"/>
        <xsd:element name="BirthDate" type="xsd:dateTime"/>
        <xsd:element name="Sex" type="fyi:sexType"/>
      </xsd:sequence>
    </xsd:complexType>
  </xsd:element>

  <xsd:simpleType name="sexType">
    <xsd:restriction base="xsd:NMTOKEN">
      <xsd:enumeration value="Male"/>
      <xsd:enumeration value="Femal"/>
    </xsd:restriction>
  </xsd:simpleType>
</xsd:schema>

⇒Using XML SAX API with Apache Xerces

⇒⇒FAQ for Apache Xerces XML Parser