SchemaFactory.java

/* SchemaFactory.java -- 
   Copyright (C) 2004, 2005, 2006  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
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package javax.xml.validation;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.net.URL;
import java.util.Properties;
import javax.xml.XMLConstants;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import org.w3c.dom.ls.LSResourceResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;

/**
 * Factory for obtaining schemata.
 *
 * @author Chris Burdess (dog@gnu.org)
 * @since 1.5
 */
public abstract class SchemaFactory
{
  protected SchemaFactory()
  {
  }

  /**
   * Returns an implementation of <code>SchemaFactory</code> that supports
   * the specified schema language.
   * @param schemaLanguage the URI of a schema language (see
   * <code>XMLConstants</code>)
   */
  public static final SchemaFactory newInstance(String schemaLanguage)
  {
    ClassLoader loader = Thread.currentThread().getContextClassLoader();
    if (loader == null)
      {
        loader = SchemaFactory.class.getClassLoader();
      }
    final String factoryClassName = "javax.xml.validation.SchemaFactory";
    String className = null;
    int count = 0;
    do
      {
        className = getFactoryClassName(loader, schemaLanguage, count++);
        if (className != null)
          {
            try
              {
                Class t = (loader != null) ? loader.loadClass(className) :
                    Class.forName(className);
                return (SchemaFactory) t.newInstance();
              }
            catch (Exception e)
              {
                // Ignore any errors and continue algorithm.
                // This method doesn't have a means of propagating
                // class instantiation errors.
                className = null;
              }
        }
    }
    while (className == null && count < 2);
    try
      {
        String serviceKey = "/META-INF/services/" + factoryClassName;
        InputStream in = (loader != null) ?
          loader.getResourceAsStream(serviceKey) :
          SchemaFactory.class.getResourceAsStream(serviceKey);
        if (in != null)
          {
            BufferedReader r =
              new BufferedReader(new InputStreamReader(in));
            try
              {
                for (String line = r.readLine(); line != null;
                        line = r.readLine())
                  {
                    Class t = (loader != null) ? loader.loadClass(className) :
                        Class.forName(className);
                    SchemaFactory ret = (SchemaFactory) t.newInstance();
                    if (ret.isSchemaLanguageSupported(schemaLanguage))
                      return ret;
                  }
              }
            catch (Exception e)
              {
                // Fall through. See above.
              }
            finally
              {
                r.close();
              }
          }
      }
    catch (IOException e)
      {
      }
    // Default schema factories for Classpath
    if (XMLConstants.W3C_XML_SCHEMA_NS_URI.equals(schemaLanguage))
      return new gnu.xml.validation.xmlschema.XMLSchemaSchemaFactory();
    if (XMLConstants.RELAXNG_NS_URI.equals(schemaLanguage))
      return new gnu.xml.validation.relaxng.RELAXNGSchemaFactory();
    throw new IllegalArgumentException(schemaLanguage);
  }

  private static String getFactoryClassName(ClassLoader loader,
          String schemaLanguage, int attempt)
  {
    final String factoryClassName = "javax.xml.validation.SchemaFactory";
    final String propertyName = factoryClassName + ":" + schemaLanguage;
    switch (attempt)
      {
        case 0:
          return System.getProperty(propertyName);
        case 1:
          try
            {
              File file = new File(System.getProperty("java.home"));
              file = new File(file, "lib");
              file = new File(file, "jaxp.properties");
              InputStream in = new FileInputStream(file);
              Properties props = new Properties();
              props.load(in);
              in.close();
              return props.getProperty(propertyName);
            }
          catch (IOException e)
            {
              return null;
            }
        default:
          return null;
      }
  }

  /**
   * Indicates whether the specified schema language is supported.
   * @param schemaLanguage the URI of a schema language (see
   * <code>XMLConstants</code>)
   */
  public abstract boolean isSchemaLanguageSupported(String schemaLanguage);

  public boolean getFeature(String name)
    throws SAXNotRecognizedException, SAXNotSupportedException
  {
    throw new SAXNotRecognizedException(name);
  }
  
  public void setFeature(String name, boolean value)
    throws SAXNotRecognizedException, SAXNotSupportedException
  {
    throw new SAXNotRecognizedException(name);
  }
  
  public Object getProperty(String name)
    throws SAXNotRecognizedException, SAXNotSupportedException
  {
    throw new SAXNotRecognizedException(name);
  }
  
  public void setProperty(String name, Object value)
    throws SAXNotRecognizedException, SAXNotSupportedException
  {
    throw new SAXNotRecognizedException(name);
  }
  
  public abstract ErrorHandler getErrorHandler();
  
  public abstract void setErrorHandler(ErrorHandler errorHandler);

  public abstract LSResourceResolver getResourceResolver();

  public abstract void setResourceResolver(LSResourceResolver resourceResolver);
  
  /**
   * Returns a schema based on the specified source resource.
   * @param schema the source resource
   */
  public Schema newSchema(Source schema)
    throws SAXException
  {
    return newSchema(new Source[] { schema });
  }

  /**
   * Returns a schema based on the specified source file.
   * @param schema the source resource
   */
  public Schema newSchema(File schema)
    throws SAXException
  {
    return newSchema(new StreamSource(schema));
  }
  
  /**
   * Returns a schema based on the specified URL.
   * @param schema the source resource
   */
  public Schema newSchema(URL schema)
    throws SAXException
  {
    return newSchema(new StreamSource(schema.toString()));
  }
  
  /**
   * Parses the specified sources, and combine them into a single schema.
   * The exact procedure and semantics of this depends on the schema
   * language.
   * @param schemata the schema resources to load
   */
  public abstract Schema newSchema(Source[] schemata)
    throws SAXException;
  
  /**
   * Creates a special schema.
   * The exact semantics of this depends on the schema language.
   */
  public abstract Schema newSchema()
    throws SAXException;
  
}