samples/dom/GetElementsByTagName.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 dom;

import java.io.PrintWriter;

import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

/**
 * A sample DOM filter. This sample program illustrates how to
 * use the Document#getElementsByTagName() method to quickly
 * and easily locate elements by name.
 *
 * @author Jeffrey Rodriguez, IBM
 * @author Andy Clark, IBM
 *
 * @version $Id$
 */
public class GetElementsByTagName {

    //
    // Constants
    //

    // feature ids

    /** Namespaces feature id (http://xml.org/sax/features/namespaces). */
    protected static final String NAMESPACES_FEATURE_ID = "http://xml.org/sax/features/namespaces";

    /** Validation feature id (http://xml.org/sax/features/validation). */
    protected static final String VALIDATION_FEATURE_ID = "http://xml.org/sax/features/validation";

    /** Schema validation feature id (http://apache.org/xml/features/validation/schema). */
    protected static final String SCHEMA_VALIDATION_FEATURE_ID = "http://apache.org/xml/features/validation/schema";

    /** Schema full checking feature id (http://apache.org/xml/features/validation/schema-full-checking). */
    protected static final String SCHEMA_FULL_CHECKING_FEATURE_ID = "http://apache.org/xml/features/validation/schema-full-checking";
    
    /** Honour all schema locations feature id (http://apache.org/xml/features/honour-all-schemaLocations). */
    protected static final String HONOUR_ALL_SCHEMA_LOCATIONS_ID = "http://apache.org/xml/features/honour-all-schemaLocations";
    
    /** Validate schema annotations feature id (http://apache.org/xml/features/validate-annotations). */
    protected static final String VALIDATE_ANNOTATIONS_ID = "http://apache.org/xml/features/validate-annotations";
    
    /** Dynamic validation feature id (http://apache.org/xml/features/validation/dynamic). */
    protected static final String DYNAMIC_VALIDATION_FEATURE_ID = "http://apache.org/xml/features/validation/dynamic";
    
    /** XInclude feature id (http://apache.org/xml/features/xinclude). */
    protected static final String XINCLUDE_FEATURE_ID = "http://apache.org/xml/features/xinclude";
    
    /** XInclude fixup base URIs feature id (http://apache.org/xml/features/xinclude/fixup-base-uris). */
    protected static final String XINCLUDE_FIXUP_BASE_URIS_FEATURE_ID = "http://apache.org/xml/features/xinclude/fixup-base-uris";
    
    /** XInclude fixup language feature id (http://apache.org/xml/features/xinclude/fixup-language). */
    protected static final String XINCLUDE_FIXUP_LANGUAGE_FEATURE_ID = "http://apache.org/xml/features/xinclude/fixup-language";

    // default settings

    /** Default parser name (dom.wrappers.Xerces). */
    protected static final String DEFAULT_PARSER_NAME = "dom.wrappers.Xerces";

    /** Default element name (*). */
    protected static final String DEFAULT_ELEMENT_NAME = "*";

    /** Default namespaces support (true). */
    protected static final boolean DEFAULT_NAMESPACES = true;

    /** Default validation support (false). */
    protected static final boolean DEFAULT_VALIDATION = false;

    /** Default Schema validation support (false). */
    protected static final boolean DEFAULT_SCHEMA_VALIDATION = false;

    /** Default Schema full checking support (false). */
    protected static final boolean DEFAULT_SCHEMA_FULL_CHECKING = false;
    
    /** Default honour all schema locations (false). */
    protected static final boolean DEFAULT_HONOUR_ALL_SCHEMA_LOCATIONS = false;
    
    /** Default validate schema annotations (false). */
    protected static final boolean DEFAULT_VALIDATE_ANNOTATIONS = false;
    
    /** Default dynamic validation support (false). */
    protected static final boolean DEFAULT_DYNAMIC_VALIDATION = false;
    
    /** Default XInclude processing support (false). */
    protected static final boolean DEFAULT_XINCLUDE = false;
    
    /** Default XInclude fixup base URIs support (true). */
    protected static final boolean DEFAULT_XINCLUDE_FIXUP_BASE_URIS = true;
    
    /** Default XInclude fixup language support (true). */
    protected static final boolean DEFAULT_XINCLUDE_FIXUP_LANGUAGE = true;

    //
    // Public static methods
    //

    /** Prints the specified elements in the given document. */
    public static void print(PrintWriter out, Document document,
                             String elementName, String attributeName) {

        // get elements that match
        NodeList elements = document.getElementsByTagName(elementName);

        // is there anything to do?
        if (elements == null) {
            return;
        }

        // print all elements
        if (attributeName == null) {
            int elementCount = elements.getLength();
            for (int i = 0; i < elementCount; i++) {
                Element element = (Element)elements.item(i);
                print(out, element, element.getAttributes());
            }
        }

        // print elements with given attribute name
        else {
            int elementCount = elements.getLength();
            for (int i = 0; i < elementCount; i++) {
                Element      element    = (Element)elements.item(i);
                NamedNodeMap attributes = element.getAttributes();
                if (attributes.getNamedItem(attributeName) != null) {
                    print(out, element, attributes);
                }
            }
        }

    } // print(PrintWriter,Document,String,String)

    //
    // Protected static methods
    //

    /** Prints the specified element. */
    protected static void print(PrintWriter out,
                                Element element, NamedNodeMap attributes) {

        out.print('<');
        out.print(element.getNodeName());
        if (attributes != null) {
            int attributeCount = attributes.getLength();
            for (int i = 0; i < attributeCount; i++) {
                Attr attribute = (Attr)attributes.item(i);
                out.print(' ');
                out.print(attribute.getNodeName());
                out.print("=\"");
                out.print(normalize(attribute.getNodeValue()));
                out.print('"');
            }
        }
        out.println('>');
        out.flush();

    } // print(PrintWriter,Element,NamedNodeMap)

    /** Normalizes the given string. */
    protected static String normalize(String s) {
        StringBuffer str = new StringBuffer();

        int len = (s != null) ? s.length() : 0;
        for (int i = 0; i < len; i++) {
            char ch = s.charAt(i);
            switch (ch) {
            case '<': {
                    str.append("&lt;");
                    break;
                }
            case '>': {
                    str.append("&gt;");
                    break;
                }
            case '&': {
                    str.append("&amp;");
                    break;
                }
            case '"': {
                    str.append("&quot;");
                    break;
                }
            case '\r':
            case '\n': {
                    str.append("&#");
                    str.append(Integer.toString(ch));
                    str.append(';');
                    break;
                }
            default: {
                    str.append(ch);
                }
            }
        }

        return str.toString();

    } // normalize(String):String

    //
    // MAIN
    //

    /** Main program entry point. */
    public static void main(String argv[]) {

        // is there anything to do?
        if (argv.length == 0) {
            printUsage();
            System.exit(1);
        }

        // variables
        PrintWriter out = new PrintWriter(System.out);
        ParserWrapper parser = null;
        String elementName = DEFAULT_ELEMENT_NAME;
        String attributeName = null;
        boolean namespaces = DEFAULT_NAMESPACES;
        boolean validation = DEFAULT_VALIDATION;
        boolean schemaValidation = DEFAULT_SCHEMA_VALIDATION;
        boolean schemaFullChecking = DEFAULT_SCHEMA_FULL_CHECKING;
        boolean honourAllSchemaLocations = DEFAULT_HONOUR_ALL_SCHEMA_LOCATIONS;
        boolean validateAnnotations = DEFAULT_VALIDATE_ANNOTATIONS;
        boolean dynamicValidation = DEFAULT_DYNAMIC_VALIDATION;
        boolean xincludeProcessing = DEFAULT_XINCLUDE;
        boolean xincludeFixupBaseURIs = DEFAULT_XINCLUDE_FIXUP_BASE_URIS;
        boolean xincludeFixupLanguage = DEFAULT_XINCLUDE_FIXUP_LANGUAGE;

        // process arguments
        for (int i = 0; i < argv.length; i++) {
            String arg = argv[i];
            if (arg.startsWith("-")) {
                String option = arg.substring(1);
                if (option.equals("p")) {
                    // get parser name
                    if (++i == argv.length) {
                        System.err.println("error: Missing argument to -p option.");
                    }
                    String parserName = argv[i];

                    // create parser
                    try {
                        parser = (ParserWrapper)Class.forName(parserName).newInstance();
                    }
                    catch (Exception e) {
                        parser = null;
                        System.err.println("error: Unable to instantiate parser ("+parserName+")");
                    }
                    continue;
                }
                if (option.equals("e")) {
                    if (++i == argv.length) {
                        System.err.println("error: Missing argument to -e option.");
                    }
                    elementName = argv[i];
                    continue;
                }
                if (option.equals("a")) {
                    if (++i == argv.length) {
                        System.err.println("error: Missing argument to -a option.");
                    }
                    attributeName = argv[i];
                    continue;
                }
                if (option.equalsIgnoreCase("n")) {
                    namespaces = option.equals("n");
                    continue;
                }
                if (option.equalsIgnoreCase("v")) {
                    validation = option.equals("v");
                    continue;
                }
                if (option.equalsIgnoreCase("s")) {
                    schemaValidation = option.equals("s");
                    continue;
                }
                if (option.equalsIgnoreCase("f")) {
                    schemaFullChecking = option.equals("f");
                    continue;
                }
                if (option.equalsIgnoreCase("hs")) {
                    honourAllSchemaLocations = option.equals("hs");
                    continue;
                }
                if (option.equalsIgnoreCase("va")) {
                    validateAnnotations = option.equals("va");
                    continue;
                }
                if (option.equalsIgnoreCase("dv")) {
                    dynamicValidation = option.equals("dv");
                    continue;
                }
                if (option.equalsIgnoreCase("xi")) {
                    xincludeProcessing = option.equals("xi");
                    continue;
                }
                if (option.equalsIgnoreCase("xb")) {
                    xincludeFixupBaseURIs = option.equals("xb");
                    continue;
                }
                if (option.equalsIgnoreCase("xl")) {
                    xincludeFixupLanguage = option.equals("xl");
                    continue;
                }
                if (option.equals("h")) {
                    printUsage();
                    continue;
                }
            }

            // use default parser?
            if (parser == null) {

                // create parser
                try {
                    parser = (ParserWrapper)Class.forName(DEFAULT_PARSER_NAME).newInstance();
                }
                catch (Exception e) {
                    System.err.println("error: Unable to instantiate parser ("+DEFAULT_PARSER_NAME+")");
                    continue;
                }
            }

            // set parser features
            try {
                parser.setFeature(NAMESPACES_FEATURE_ID, namespaces);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+NAMESPACES_FEATURE_ID+")");
            }
            try {
                parser.setFeature(VALIDATION_FEATURE_ID, validation);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+VALIDATION_FEATURE_ID+")");
            }
            try {
                parser.setFeature(SCHEMA_VALIDATION_FEATURE_ID, schemaValidation);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+SCHEMA_VALIDATION_FEATURE_ID+")");
            }
            try {
                parser.setFeature(SCHEMA_FULL_CHECKING_FEATURE_ID, schemaFullChecking);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+SCHEMA_FULL_CHECKING_FEATURE_ID+")");
            }
            try {
                parser.setFeature(HONOUR_ALL_SCHEMA_LOCATIONS_ID, honourAllSchemaLocations);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+HONOUR_ALL_SCHEMA_LOCATIONS_ID+")");
            }
            try {
                parser.setFeature(VALIDATE_ANNOTATIONS_ID, validateAnnotations);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+VALIDATE_ANNOTATIONS_ID+")");
            }
            try {
                parser.setFeature(DYNAMIC_VALIDATION_FEATURE_ID, dynamicValidation);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+DYNAMIC_VALIDATION_FEATURE_ID+")");
            }
            try {
                parser.setFeature(XINCLUDE_FEATURE_ID, xincludeProcessing);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+XINCLUDE_FEATURE_ID+")");
            }
            try {
                parser.setFeature(XINCLUDE_FIXUP_BASE_URIS_FEATURE_ID, xincludeFixupBaseURIs);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+XINCLUDE_FIXUP_BASE_URIS_FEATURE_ID+")");
            }
            try {
                parser.setFeature(XINCLUDE_FIXUP_LANGUAGE_FEATURE_ID, xincludeFixupLanguage);
            }
            catch (SAXException e) {
                System.err.println("warning: Parser does not support feature ("+XINCLUDE_FIXUP_LANGUAGE_FEATURE_ID+")");
            }

            // parse file
            try {
                Document document = parser.parse(arg);
                GetElementsByTagName.print(out, document, elementName, attributeName);
            }
            catch (SAXParseException e) {
                // ignore
            }
            catch (Exception e) {
                System.err.println("error: Parse error occurred - "+e.getMessage());
                if (e instanceof SAXException) {
                    Exception nested = ((SAXException)e).getException();
                    if (nested != null) {
                        e = nested;
                    }
                }
                e.printStackTrace(System.err);
            }
        }

    } // main(String[])

    //
    // Private static methods
    //

    /** Prints the usage. */
    private static void printUsage() {

        System.err.println("usage: java dom.GetElementsByTagName (options) uri ...");
        System.err.println();

        System.err.println("options:");
        System.err.println("  -p name     Select parser by name.");
        System.err.println("  -e name     Specify element name for search.");
        System.err.println("  -a name     Specify attribute name for specified elements.");
        System.err.println("  -n | -N     Turn on/off namespace processing.");
        System.err.println("  -v | -V     Turn on/off validation.");
        System.err.println("  -s | -S     Turn on/off Schema validation support.");
        System.err.println("              NOTE: Not supported by all parsers.");
        System.err.println("  -f  | -F    Turn on/off Schema full checking.");
        System.err.println("              NOTE: Requires use of -s and not supported by all parsers.");
        System.err.println("  -hs | -HS   Turn on/off honouring of all schema locations.");
        System.err.println("              NOTE: Requires use of -s and not supported by all parsers.");
        System.err.println("  -va | -VA   Turn on/off validation of schema annotations.");
        System.err.println("              NOTE: Requires use of -s and not supported by all parsers.");
        System.err.println("  -dv | -DV   Turn on/off dynamic validation.");
        System.err.println("              NOTE: Not supported by all parsers.");
        System.err.println("  -xi | -XI   Turn on/off XInclude processing.");
        System.err.println("              NOTE: Not supported by all parsers.");
        System.err.println("  -xb | -XB   Turn on/off base URI fixup during XInclude processing.");
        System.err.println("              NOTE: Requires use of -xi and not supported by all parsers.");
        System.err.println("  -xl | -XL   Turn on/off language fixup during XInclude processing.");
        System.err.println("              NOTE: Requires use of -xi and not supported by all parsers.");
        System.err.println("  -h          This help screen.");
        System.err.println();

        System.err.println("defaults:");
        System.err.println("  Parser:     "+DEFAULT_PARSER_NAME);
        System.err.println("  Element:    "+DEFAULT_ELEMENT_NAME);
        System.err.print("  Namespaces: ");
        System.err.println(DEFAULT_NAMESPACES ? "on" : "off");
        System.err.print("  Validation: ");
        System.err.println(DEFAULT_VALIDATION ? "on" : "off");
        System.err.print("  Schema:     ");
        System.err.println(DEFAULT_SCHEMA_VALIDATION ? "on" : "off");
        System.err.print("  Schema full checking:            ");
        System.err.println(DEFAULT_SCHEMA_FULL_CHECKING ? "on" : "off");
        System.err.print("  Honour all schema locations:     ");
        System.err.println(DEFAULT_HONOUR_ALL_SCHEMA_LOCATIONS ? "on" : "off");
        System.err.print("  Validate annotations:            ");
        System.err.println(DEFAULT_VALIDATE_ANNOTATIONS ? "on" : "off");
        System.err.print("  Dynamic:    ");
        System.err.println(DEFAULT_DYNAMIC_VALIDATION ? "on" : "off");
        System.err.print("  XInclude:   ");
        System.err.println(DEFAULT_XINCLUDE ? "on" : "off");
        System.err.print("  XInclude base URI fixup:  ");
        System.err.println(DEFAULT_XINCLUDE_FIXUP_BASE_URIS ? "on" : "off");
        System.err.print("  XInclude language fixup:  ");
        System.err.println(DEFAULT_XINCLUDE_FIXUP_LANGUAGE ? "on" : "off");

    } // printUsage()

} // class GetElementsByTagName