XSD Schema File Loader - XsdSchemaLoader.java

XSD Tutorials - Herong's Tutorial Examples

∟XSD Schema File Loader - XsdSchemaLoader.java

This section describes a tutorial example on how to create an XSD schema file loader using JAXP Schema and SchemaFactory classes.

As we can see from the standard steps described in the previous tutorial, the first thing we need to do is to create SchemaFactory instance. Then use it to create a Schema instance by parsing the schema file.

Here is simple tutorial example code called XsdSchemaLoader.java that parses a schema file and create a Schema instance:

/* XsdSchemaLoader.java
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
 */
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Schema;
import javax.xml.XMLConstants;
import java.io.File;
class XsdSchemaLoader {
  public static void main(String[] a) {
    if (a.length<1) {
      System.out.println("Usage:");
      System.out.println("java XsdSchemaLoader schema_file_name");
    } else {
      String name = a[0];
      Schema schema = loadSchema(name);
    }
  }
  public static Schema loadSchema(String name) {
    Schema schema = null;
    try {

      // getting the default implementation of XML Schema factory
      String language = XMLConstants.W3C_XML_SCHEMA_NS_URI;
      SchemaFactory factory = SchemaFactory.newInstance(language);
      System.out.println();
      System.out.println("Schema Language: "+language);
      System.out.println("Factory Class: "
        + factory.getClass().getName());

      // parsing the schema file
      schema = factory.newSchema(new File(name));
      System.out.println();
      System.out.println("Schema File: "+name);
      System.out.println("Schema Class: "
        + schema.getClass().getName());

    } catch (Exception e) {
      // catching all exceptions
      System.out.println();
      System.out.println(e.toString());
    }
    return schema;
  }
}

As the first test, let's try to load the following simple XSD schema file, first_html.xsd:

<?xml version = "1.0" encoding = "utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified" attributeFormDefault="unqualified">
 <xs:element name="html" type="htmlType"/>
 <xs:complexType name="htmlType">
  <xs:sequence>
   <xs:element name="body" type="xs:string"/>
  </xs:sequence>
 </xs:complexType>
</xs:schema>

Here is what you will get as output in JDK 13, which has not been changed since JDK 1.6:

herong> java XsdSchemaLoader.java first_html.xsd

Schema Language: http://www.w3.org/2001/XMLSchema
Factory Class: com.sun.org.apache.xerces.internal.jaxp.validation.XMLSchemaFactory

Schema File: first_html.xsd
Schema Class: com.sun.org.apache.xerces.internal.jaxp.validation.SimpleXMLSchema

The output shows that:

The default implementation class of the XML Schema language factory is from the Apache Xerces project.
The default implementation class of the schema presentation is also from the Apache Xerces project.