Java example source code file (BootstrapResolver.java)

This example Java source code file (BootstrapResolver.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bootstrapresolver, catalogs, entityresolver, hashtable, inputsource, inputstream, malformedurlexception, net, network, oasis\/\/dtd, sax, saxsource, string, transformerexception, uriresolver, url, util, xml

The BootstrapResolver.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
// BootstrapResolver.java - Resolve entities and URIs internally

/*
 * Copyright 2001-2004 The Apache Software Foundation or its licensors,
 * as applicable.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xml.internal.resolver.helpers;

import java.util.Hashtable;
import java.net.URL;
import java.net.MalformedURLException;
import java.io.InputStream;

import javax.xml.transform.URIResolver;
import javax.xml.transform.Source;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.TransformerException;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;

/**
 * A simple bootstrapping resolver.
 *
 * <p>This class is used as the entity resolver when reading XML Catalogs.
 * It searches for the OASIS XML Catalog DTD, Relax NG Grammar and W3C XML Schema
 * as resources (e.g., in the resolver jar file).</p>
 *
 * <p>If you have your own DTDs or schemas, you can extend this class and
 * set the BootstrapResolver in your CatalogManager.</p>
 *
 * @see com.sun.org.apache.xml.internal.resolver.CatalogManager
 *
 * @author Norman Walsh
 * <a href="mailto:Norman.Walsh@Sun.COM">Norman.Walsh@Sun.COM
 *
 */
public class BootstrapResolver implements EntityResolver, URIResolver {
  /** URI of the W3C XML Schema for OASIS XML Catalog files. */
  public static final String xmlCatalogXSD = "http://www.oasis-open.org/committees/entity/release/1.0/catalog.xsd";

  /** URI of the RELAX NG Grammar for OASIS XML Catalog files. */
  public static final String xmlCatalogRNG = "http://www.oasis-open.org/committees/entity/release/1.0/catalog.rng";

  /** Public identifier for OASIS XML Catalog files. */
  public static final String xmlCatalogPubId = "-//OASIS//DTD XML Catalogs V1.0//EN";

  /** System identifier for OASIS XML Catalog files. */
  public static final String xmlCatalogSysId = "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd";

  /** Private hash used for public identifiers. */
  private Hashtable publicMap = new Hashtable();

  /** Private hash used for system identifiers. */
  private Hashtable systemMap = new Hashtable();

  /** Private hash used for URIs. */
  private Hashtable uriMap = new Hashtable();

  /** Constructor. */
  public BootstrapResolver() {
    URL url = this.getClass().getResource("/com/sun/org/apache/xml/internal/resolver/etc/catalog.dtd");
    if (url != null) {
      publicMap.put(xmlCatalogPubId, url.toString());
      systemMap.put(xmlCatalogSysId, url.toString());
    }

    url = this.getClass().getResource("/com/sun/org/apache/xml/internal/resolver/etc/catalog.rng");
    if (url != null) {
      uriMap.put(xmlCatalogRNG, url.toString());
    }

    url = this.getClass().getResource("/com/sun/org/apache/xml/internal/resolver/etc/catalog.xsd");
    if (url != null) {
      uriMap.put(xmlCatalogXSD, url.toString());
    }
  }

  /** SAX resolveEntity API. */
  public InputSource resolveEntity (String publicId, String systemId) {
    String resolved = null;

    if (systemId != null && systemMap.containsKey(systemId)) {
      resolved = (String) systemMap.get(systemId);
    } else if (publicId != null && publicMap.containsKey(publicId)) {
      resolved = (String) publicMap.get(publicId);
    }

    if (resolved != null) {
      try {
        InputSource iSource = new InputSource(resolved);
        iSource.setPublicId(publicId);

        // Ideally this method would not attempt to open the
        // InputStream, but there is a bug (in Xerces, at least)
        // that causes the parser to mistakenly open the wrong
        // system identifier if the returned InputSource does
        // not have a byteStream.
        //
        // It could be argued that we still shouldn't do this here,
        // but since the purpose of calling the entityResolver is
        // almost certainly to open the input stream, it seems to
        // do little harm.
        //
        URL url = new URL(resolved);
        InputStream iStream = url.openStream();
        iSource.setByteStream(iStream);

        return iSource;
      } catch (Exception e) {
        // FIXME: silently fail?
        return null;
      }
    }

    return null;
  }

  /** Transformer resolve API. */
  public Source resolve(String href, String base)
    throws TransformerException {

    String uri = href;
    String fragment = null;
    int hashPos = href.indexOf("#");
    if (hashPos >= 0) {
      uri = href.substring(0, hashPos);
      fragment = href.substring(hashPos+1);
    }

    String result = null;
    if (href != null && uriMap.containsKey(href)) {
      result = (String) uriMap.get(href);
    }

    if (result == null) {
      try {
        URL url = null;

        if (base==null) {
          url = new URL(uri);
          result = url.toString();
        } else {
          URL baseURL = new URL(base);
          url = (href.length()==0 ? baseURL : new URL(baseURL, uri));
          result = url.toString();
        }
      } catch (java.net.MalformedURLException mue) {
        // try to make an absolute URI from the current base
        String absBase = makeAbsolute(base);
        if (!absBase.equals(base)) {
          // don't bother if the absBase isn't different!
          return resolve(href, absBase);
        } else {
          throw new TransformerException("Malformed URL "
                                         + href + "(base " + base + ")",
                                         mue);
        }
      }
    }

    SAXSource source = new SAXSource();
    source.setInputSource(new InputSource(result));
    return source;
  }

  /** Attempt to construct an absolute URI */
  private String makeAbsolute(String uri) {
    if (uri == null) {
      uri = "";
    }

    try {
      URL url = new URL(uri);
      return url.toString();
    } catch (MalformedURLException mue) {
      try {
        URL fileURL = FileURL.makeURL(uri);
        return fileURL.toString();
      } catch (MalformedURLException mue2) {
        // bail
        return uri;
      }
    }
  }
}