org.openide.xml

Class XMLUtil

java.lang.Object

org.openide.xml.XMLUtil

public final class XMLUtil
extends Object

Utility class collecting library methods related to XML processing.

Method Summary

Modifier and Type	Method and Description
static void	appendChildElement(Element parent, Element el, String[] order) Append a child element to the parent at the specified location.
static void	copyDocument(Element from, Element to, String newNamespace) Copy elements from one document to another attaching at the specified element and translating the namespace.
static Document	createDocument(String rootQName, String namespaceURI, String doctypePublicID, String doctypeSystemID) Creates an empty DOM document.
static XMLReader	createXMLReader() Create a simple parser.
static XMLReader	createXMLReader(boolean validate) Create a simple parser, possibly validating.
static XMLReader	createXMLReader(boolean validate, boolean namespaceAware) Creates a SAX parser.
static ErrorHandler	defaultErrorHandler() Create an XML error handler that rethrows errors and fatal errors and logs warnings.
static Element	findElement(Element parent, String name, String namespace) Search for an XML element in the direct children of parent only.
static List<Element>	findSubElements(Element parent) Find all direct child elements of an element.
static String	findText(Node parent) Extract nested text from a node.
static byte[]	fromHex(char[] hex, int start, int len) Decodes data encoded using toHex.
static Document	parse(InputSource input, boolean validate, boolean namespaceAware, ErrorHandler errorHandler, EntityResolver entityResolver) Parses an XML document into a DOM tree.
static String	toAttributeValue(String val) Escape passed string as XML attibute value (<, &, ' and " will be escaped.
static String	toElementContent(String val) Escape passed string as XML element content (<, & and > in ]]> sequences).
static String	toHex(byte[] val, int start, int len) Can be used to encode values that contain invalid XML characters.
static Element	translateXML(Element from, String namespace) Convert an XML fragment from one namespace to another.
static void	validate(Element data, Schema schema) Check whether a DOM tree is valid according to a schema.
static void	write(Document doc, OutputStream out, String enc) Writes a DOM document to a stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

createXMLReader

public static XMLReader createXMLReader()
                                 throws SAXException

Create a simple parser.

Returns:

createXMLReader(false, false)

Throws:

SAXException

createXMLReader

public static XMLReader createXMLReader(boolean validate)
                                 throws SAXException

Create a simple parser, possibly validating.

Parameters:

validate - if true, a validating parser is returned

Returns:

createXMLReader(validate, false)

Throws:

SAXException

createXMLReader

public static XMLReader createXMLReader(boolean validate,
                                        boolean namespaceAware)
                                 throws SAXException

Creates a SAX parser.

See XMLUtil.parse(org.xml.sax.InputSource, boolean, boolean, org.xml.sax.ErrorHandler, org.xml.sax.EntityResolver) for hints on setting an entity resolver.

Parameters:

validate - if true, a validating parser is returned

namespaceAware - if true, a namespace aware parser is returned

Returns:

XMLReader configured according to passed parameters

Throws:

FactoryConfigurationError - Application developers should never need to directly catch errors of this type.

SAXException - if a parser fulfilling given parameters can not be created

createDocument

public static Document createDocument(String rootQName,
                                      String namespaceURI,
                                      String doctypePublicID,
                                      String doctypeSystemID)
                               throws DOMException

Creates an empty DOM document. E.g.:

 Document doc = createDocument("book", null, null, null);
 

creates new DOM of a well-formed document with root element named book.

Parameters:

rootQName - qualified name of root element. e.g. myroot or ns:myroot

namespaceURI - URI of root element namespace or null

doctypePublicID - public ID of DOCTYPE or null

doctypeSystemID - system ID of DOCTYPE or null if no DOCTYPE required and doctypePublicID is also null

Returns:

new DOM Document

Throws:

DOMException - if new DOM with passed parameters can not be created

FactoryConfigurationError - Application developers should never need to directly catch errors of this type.

parse

public static Document parse(InputSource input,
                             boolean validate,
                             boolean namespaceAware,
                             ErrorHandler errorHandler,
                             EntityResolver entityResolver)
                      throws IOException,
                             SAXException

Parses an XML document into a DOM tree.

Remember that when parsing XML files you often want to set an explicit entity resolver. For example, consider a file such as this:

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE root PUBLIC "-//NetBeans//DTD Foo 1.0//EN" "http://www.netbeans.org/dtds/foo-1_0.dtd">
 <root/>
 

If you parse this with a null entity resolver, or you use the default resolver (EntityCatalog.getDefault()) but do not do anything special with this DTD, you will probably find the parse blocking to make a network connection even when you are not validating. That is because DTDs can be used to define entities and other XML oddities, and are not a pure constraint language like Schema or RELAX-NG.

There are three basic ways to avoid the network connection.

1. Register the DTD. This is generally the best thing to do. See EntityCatalog's documentation for details, but for example in your layer use:

    <filesystem>
      <folder name="xml">
        <folder name="entities">
          <folder name="NetBeans">
            <file name="DTD_Foo_1_0"
                  url="resources/foo-1_0.dtd">
              <attr name="hint.originalPublicID"
                    stringvalue="-//NetBeans//DTD Foo 1.0//EN"/>
            </file>
          </folder>
        </folder>
      </folder>
    </filesystem>
    

   Now the default system entity catalog will resolve the public ID to the local copy in your module, not the network copy. Additionally, anyone who mounts the "NetBeans Catalog" in the XML Entity Catalogs node in the Runtime tab will be able to use your local copy of the DTD automatically, for validation, code completion, etc. (The network URL should really exist, though, for the benefit of other tools!)

2. You can also set an explicit entity resolver which maps that particular public ID to some local copy of the DTD, if you do not want to register it globally in the system for some reason. If handed other public IDs, just return null to indicate that the system ID should be loaded.

3. In some cases where XML parsing is very performance-sensitive, and you know that you do not need validation and furthermore that the DTD defines no infoset (there are no entity or character definitions, etc.), you can speed up the parse. Turn off validation, but also supply a custom entity resolver that does not even bother to load the DTD at all:

    public InputSource resolveEntity(String pubid, String sysid)
        throws SAXException, IOException {
      if (pubid.equals("-//NetBeans//DTD Foo 1.0//EN")) {
        return new InputSource(new ByteArrayInputStream(new byte[0]));
      } else {
        return EntityCatalog.getDefault().resolveEntity(pubid, sysid);
      }
    }
    

Parameters:

input - a parser input (for URL users use: new InputSource(url.toString())

validate - if true validating parser is used

namespaceAware - if true DOM is created by namespace aware parser

errorHandler - a error handler to notify about exception (such as XMLUtil.defaultErrorHandler()) or null

entityResolver - SAX entity resolver (such as EntityCatalog.getDefault()) or null

Returns:

document representing given input

Throws:

IOException - if an I/O problem during parsing occurs

SAXException - is thrown if a parser error occurs

FactoryConfigurationError - Application developers should never need to directly catch errors of this type.

write

public static void write(Document doc,
                         OutputStream out,
                         String enc)
                  throws IOException

Writes a DOM document to a stream. The precise output format is not guaranteed but this method will attempt to indent it sensibly.

Important: There might be some problems with <![CDATA[ ]]> sections in the DOM tree you pass into this method. Specifically, some CDATA sections my not be written as CDATA section or may be merged with other CDATA section at the same level. Also if plain text nodes are mixed with CDATA sections at the same level all text is likely to end up in one big CDATA section.
For nodes that only have one CDATA section this method should work fine.

Parameters:

doc - DOM document to be written

out - data sink

enc - XML-defined encoding name (e.g. "UTF-8")

Throws:

IOException - if JAXP fails or the stream cannot be written to

validate

public static void validate(Element data,
                            Schema schema)
                     throws SAXException

Check whether a DOM tree is valid according to a schema. Example of usage:

 Element fragment = ...;
 SchemaFactory f = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
 Schema s = f.newSchema(This.class.getResource("something.xsd"));
 try {
     XMLUtil.validate(fragment, s);
     // valid
 } catch (SAXException x) {
     // invalid
 }
 

Parameters:

data - a DOM tree

schema - a parsed schema

Throws:

SAXException - if validation failed

Since:

org.openide.util 7.17

toAttributeValue

public static String toAttributeValue(String val)
                               throws CharConversionException

Escape passed string as XML attibute value (<, &, ' and " will be escaped. Note: An XML processor returns normalized value that can be different.

Parameters:

val - a string to be escaped

Returns:

escaped value

Throws:

CharConversionException - if val contains an improper XML character

Since:

1.40

toElementContent

public static String toElementContent(String val)
                               throws CharConversionException

Escape passed string as XML element content (<, & and > in ]]> sequences).

Parameters:

val - a string to be escaped

Returns:

escaped value

Throws:

CharConversionException - if val contains an improper XML character

Since:

1.40

toHex

public static String toHex(byte[] val,
                           int start,
                           int len)

Can be used to encode values that contain invalid XML characters. At SAX parser end must be used pair method to get original value.

Parameters:

val - data to be converted

start - offset

len - count

Since:

1.29

fromHex

public static byte[] fromHex(char[] hex,
                             int start,
                             int len)
                      throws IOException

Decodes data encoded using toHex.

Parameters:

hex - data to be converted

start - offset

len - count

Throws:

IOException - if input does not represent hex encoded value

Since:

1.29

appendChildElement

public static void appendChildElement(Element parent,
                                      Element el,
                                      String[] order)
                               throws IllegalArgumentException

Append a child element to the parent at the specified location. Starting with a valid document, append an element according to the schema sequence represented by the order. All existing child elements must be include as well as the new element. The existing child element following the new child is important, as the element will be 'inserted before', not 'inserted after'.

Parameters:

parent - parent to which the child will be appended

el - element to be added

order - order of the elements which must be followed

Throws:

IllegalArgumentException - if the order cannot be followed, either a missing existing or new child element is not specified in order

Since:

8.4

findSubElements

public static List<Element> findSubElements(Element parent)
                                     throws IllegalArgumentException

Find all direct child elements of an element. Children which are all-whitespace text nodes or comments are ignored; others cause an exception to be thrown.

Parameters:

parent - a parent element in a DOM tree

Returns:

a list of direct child elements (may be empty)

Throws:

IllegalArgumentException - if there are non-element children besides whitespace

Since:

8.4

findElement

public static Element findElement(Element parent,
                                  String name,
                                  String namespace)
                           throws IllegalArgumentException

Search for an XML element in the direct children of parent only. This compares localName (nodeName if localName is null) to name, and checks the tags namespace with the provided namespace. A null namespace will match any namespace.

This is differs from the DOM version by:
• not searching recursively
• returns a single result

Parameters:

parent - a parent element

name - the intended local name

namespace - the intended namespace (or null)

Returns:

the one child element with that name, or null if none

Throws:

IllegalArgumentException - if there is multiple elements of the same name

Since:

8.4

findText

public static String findText(Node parent)

Extract nested text from a node. Currently does not handle coalescing text nodes, CDATA sections, etc.

Parameters:

parent - a parent element

Returns:

the nested text, or null if none was found

Since:

8.4

translateXML

public static Element translateXML(Element from,
                                   String namespace)

Convert an XML fragment from one namespace to another.

Parameters:

from - element to translate

namespace - namespace to be translated to

Returns:

Since:

8.4

copyDocument

public static void copyDocument(Element from,
                                Element to,
                                String newNamespace)

Copy elements from one document to another attaching at the specified element and translating the namespace.

Parameters:

from - copy the children of this element (exclusive)

to - where to attach the copied elements

newNamespace - destination namespace

Since:

8.4

defaultErrorHandler

public static ErrorHandler defaultErrorHandler()

Create an XML error handler that rethrows errors and fatal errors and logs warnings.

Returns:

a standard error handler

Since:

8.4