Use the Document.getElementsByTagName() method to quickly and easily locate elements by name.
/*
* 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.
*/
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.w3c.dom.Text;
import org.xml.sax.SAXException;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
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: GetElementsByTagName.java 447683 2006-09-19 02:36:31Z mrglavas $
*/
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("<");
break;
}
case '>': {
str.append(">");
break;
}
case '&': {
str.append("&");
break;
}
case '"': {
str.append(""");
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
/**
* Encapsulates a DOM parser.
*
* @version $Id: ParserWrapper.java 447683 2006-09-19 02:36:31Z mrglavas $
*/
interface ParserWrapper {
//
// ParserWrapper methods
//
/** Parses the specified URI and returns the document. */
public Document parse(String uri) throws Exception;
/**
* Set the state of a feature.
*
* Set the state of any feature in a SAX2 parser. The parser
* might not recognize the feature, and if it does recognize
* it, it might not be able to fulfill the request.
*
* @param featureId The unique identifier (URI) of the feature.
* @param state The requested state of the feature (true or false).
*
* @exception org.xml.sax.SAXNotRecognizedException If the
* requested feature is not known.
* @exception org.xml.sax.SAXNotSupportedException If the
* requested feature is known, but the requested
* state is not supported.
* @exception org.xml.sax.SAXException If there is any other
* problem fulfilling the request.
*/
public void setFeature(String featureId, boolean state)
throws SAXNotRecognizedException, SAXNotSupportedException;
/** Returns the document information. */
public DocumentInfo getDocumentInfo();
//
// Interfaces
//
/**
* This interface is here to query information about the document
* implementation returned by the <code>ParserWrapper#parse</code>
* method.
*
* @author Andy Clark, IBM
*/
public interface DocumentInfo {
//
// DocumentInfo methods
//
/**
* Returns true if the specified text node is ignorable whitespace.
*/
public boolean isIgnorableWhitespace(Text text);
} // interface DocumentInfo
} // interface ParserWrapper
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