/*
* JBoss, Home of Professional Open Source
*
* Distributable under LGPL license.
* See terms of license at gnu.org.
*/
package org.jboss.cache.xml;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
/**
* A simple XML utility class for reading configuration elements
*
* @author <a href="mailto:manik@jboss.org">Manik Surtani (manik@jboss.org)</a>
*/
public class XmlHelper
{
private static Log log = LogFactory.getLog(XmlHelper.class);
/**
* The root of a JBoss Cache configuration XML file. This is the <tt><mbean></tt> tag.
*/
public static final String ROOT = "mbean";
/**
* The <tt><attribute></tt> tag which forms the bulk of JBoss Cache configuration elements
*/
public static final String ATTR = "attribute";
/**
* The <tt><config></tt> tag may be embedded in the contents of an <tt><attribute></tt>, to specify more
* complex configuration for certain parameters.
*/
public static final String CONFIG_ATTR = "config";
/**
* The <tt><name></tt> attribute to an <tt><attribute></tt> tag.
*/
public static final String NAME = "name";
/**
* Returns the contents of a specific node of given element name, provided a certain attribute exists and is set to value.
* E.g., if you have a {@link Element} which represents the following XML snippet:
* <pre>
* <ItemQuantity Colour="Red">100</ItemQuantity>
* <ItemQuantity Colour="Blue">30</ItemQuantity>
* <ItemQuantity Colour="Black">10</ItemQuantity>
* <pre>
* <p/>
* The following results could be expected:
* </p>
* <pre>
* getTagContents(element, "Red", "ItemQuantity", "Colour"); // 100
* getTagContents(element, "Black", "ItemQuantity", "Colour"); // 10
* getTagContents(element, "Blah", "ItemQuantity", "Colour"); // null
* getTagContents(element, "Red", "Blah", "Colour"); // null
* getTagContents(element, "Black", "ItemQuantity", "Blah"); // null
* </pre>
* <p/>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
* </p>
*
* @param elem - element to search through.
* @param value - expected value to match against
* @param elementName - element name
* @param attributeName - attribute name of the element that would contain the expected value.
* @return the contents of the matched element, or null if not found/matched
*/
public static String getTagContents(Element elem, String value, String elementName, String attributeName)
{
NodeList list = elem.getElementsByTagName(elementName);
for (int s = 0; s < list.getLength(); s++)
{
org.w3c.dom.Node node = list.item(s);
if (node.getNodeType() != org.w3c.dom.Node.ELEMENT_NODE)
continue;
Element element = (Element) node;
String name = element.getAttribute(attributeName);
if (name.equals(value))
{
return getElementContent(element, true);
}
}
return null;
}
/**
* Retrieves the value of a given attribute for the first encountered instance of a tag in an element.
* <p/>
* E.g., if you have a {@link Element} which represents the following XML snippet:
* </p>
* <pre>
* <ItemQuantity Colour="Red">100</ItemQuantity>
* <ItemQuantity Colour="Blue">30</ItemQuantity>
* <ItemQuantity Colour="Black">10</ItemQuantity>
* <pre>
* <p/>
* The following results could be expected:
* </p>
* <pre>
* getAttributeValue(element, "ItemQuantity", "Colour"); // "Red"
* getTagContents(element, "Blah", "Colour"); // null
* getTagContents(element, "ItemQuantity", "Blah"); // null
* </pre>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
*
* @param elem - element to search through.
* @param elementName - element name
* @param attributeName - attribute name of the element that would contain the expected value.
* @return the contents of the matched attribute, or null if not found/matched
*/
public static String getAttributeValue(Element elem, String elementName, String attributeName)
{
NodeList list = elem.getElementsByTagName(elementName);
for (int s = 0; s < list.getLength(); s++)
{
org.w3c.dom.Node node = list.item(s);
if (node.getNodeType() != org.w3c.dom.Node.ELEMENT_NODE)
continue;
Element element = (Element) node;
return element.getAttribute(attributeName);
}
return null;
}
/**
* Convenience method, equivalent to calling <tt>getSubElement(element, "config");</tt>
*/
public static Element getConfigSubElement(Element element)
{
return getSubElement(element, CONFIG_ATTR);
}
/**
* Returns a named sub-element of the current element passed in.
* <p/>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
*
* @param element - element to search through.
* @param subElementName - the name of a sub element to look for
* @return the first matching sub element, if found, or null otherwise.
*/
public static Element getSubElement(Element element, String subElementName)
{
NodeList nl = element.getChildNodes();
for (int i = 0; i < nl.getLength(); i++)
{
Node node = nl.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE && subElementName.equals(((Element) node).getTagName()))
{
return (Element) node;
}
}
if (log.isDebugEnabled()) log.debug("getSubElement(): Does not exist for " + subElementName);
return null;
}
/**
* Reads the contents of the element passed in.
* <p/>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
*
* @param element - element to search through.
* @param trim - if true, whitespace is trimmed before returning
* @return the contents of the element passed in. Will return an empty String if the element is empty.
*/
public static String getElementContent(Element element, boolean trim)
{
NodeList nl = element.getChildNodes();
String attributeText = "";
for (int i = 0; i < nl.getLength(); i++)
{
Node n = nl.item(i);
if (n instanceof Text)
{
attributeText += ((Text) n).getData();
}
} // end of for ()
if (trim)
attributeText = attributeText.trim();
return attributeText;
}
/**
* Reads the contents of the first occurence of elementName under the given element, trimming results of whitespace.
* <p/>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
*
* @param element - element to search through.
* @param elementName - name of the element to find within the element passed in
* @return may return an empty String of not found.
*/
public static String readStringContents(Element element, String elementName)
{
NodeList nodes = element.getElementsByTagName(elementName);
if (nodes.getLength() > 0)
{
Node node = nodes.item(0);
Element ne = (Element) node;
NodeList nl2 = ne.getChildNodes();
Node node2 = nl2.item(0);
if (node2 != null)
{
String value = node2.getNodeValue();
if (value == null)
return "";
return value.trim();
}
else
{
return "";
}
}
else
{
return "";
}
}
/**
* Escapes backslashes ('\') with additional backslashes in a given String, returning a new, escaped String.
*
* @param value String to escape. Cannot be null.
* @return escaped String. Never is null.
*/
public static String escapeBackslashes(String value)
{
StringBuffer buf = new StringBuffer(value);
for (int looper = 0; looper < buf.length(); looper++)
{
char curr = buf.charAt(looper);
char next = 0;
if (looper + 1 < buf.length())
next = buf.charAt(looper + 1);
if (curr == '\\')
{
if (next != '\\')
{ // only if not already escaped
buf.insert(looper, '\\'); // escape backslash
}
looper++; // skip past extra backslash (either the one we added or existing)
}
}
return buf.toString();
}
/**
* Reads the contents of a named sub element within a given element, and attempts to parse the contents as a Java
* properties file.
* <p/>
* E.g., if you have a {@link Element} which represents the following XML snippet:
* <p/>
* <pre>
* <props>
* my.attrib.1 = blah
* my.attrib.2 = blahblah
* </props>
* <pre>
* <p/>
* The following results could be expected:
* <p/>
* <pre>
* Properties p = readPropertiesContents(element, "props");
* p.getProperty("my.attrib.1"); // blah
* p.getProperty("my.attrib.2"); // blahblah
* </pre>
* None of the parameters should be null - otherwise the method may throw a NullPointerException.
*
* @param element - element to search through.
* @param elementName - name of the element to find within the element passed in
* @return a {@link Properties} object, never null.
* @throws IOException if unable to parse the contents of the element
*/
public static Properties readPropertiesContents(Element element, String elementName) throws IOException
{
String stringContents = readStringContents(element, elementName);
if (stringContents == null) return new Properties();
// JBCACHE-531: escape all backslash characters
stringContents = escapeBackslashes(stringContents);
ByteArrayInputStream is = new ByteArrayInputStream(stringContents.trim().getBytes("ISO8859_1"));
Properties properties = new Properties();
properties.load(is);
is.close();
return properties;
}
/**
* Similar to {@link #readStringContents(org.w3c.dom.Element,String)} except that it returns a boolean.
*
* @param element - element to search through.
* @param elementName - name of the element to find within the element passed in
* @return the contents of the element as a boolean, or false if not found.
*/
public static boolean readBooleanContents(Element element, String elementName)
{
return readBooleanContents(element, elementName, false);
}
/**
* Similar to {@link #readStringContents(org.w3c.dom.Element,String)} except that it returns a boolean.
*
* @param element - element to search through.
* @param elementName - name of the element to find within the element passed in
* @param defaultValue - value to return if the element is not found or cannot be parsed.
* @return the contents of the element as a boolean
*/
public static boolean readBooleanContents(Element element, String elementName, boolean defaultValue)
{
String val = readStringContents(element, elementName);
if (val.equalsIgnoreCase("true") || val.equalsIgnoreCase("false"))
{
// needs to be done this way because of JBBUILD-351
return Boolean.valueOf(val);
//return Boolean.parseBoolean(val);
}
return defaultValue;
}
/**
* Converts a String representing an XML snippet into an {@link org.w3c.dom.Element}.
*
* @param xml snippet as a string
* @return a DOM Element
* @throws Exception if unable to parse the String or if it doesn't contain valid XML.
*/
public static Element stringToElement(String xml) throws Exception
{
ByteArrayInputStream bais = new ByteArrayInputStream(xml.getBytes("utf8"));
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document d = builder.parse(bais);
bais.close();
return d.getDocumentElement();
}
/**
* Returns the root element of a given input stream
*
* @param is stream to parse
* @return XML DOM element, or null if unable to parse stream
*/
public static Element getDocumentRoot(InputStream is)
{
Document doc;
try
{
InputSource xmlInp = new InputSource(is);
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder parser = docBuilderFactory.newDocumentBuilder();
doc = parser.parse(xmlInp);
Element root = doc.getDocumentElement();
root.normalize();
return root;
}
catch (SAXParseException err)
{
log.error("Configurator SAXParse error", err);
}
catch (SAXException e)
{
log.error("Configurator SAX error", e);
}
catch (Exception pce)
{
log.error("Configurator general error", pce);
}
return null;
}
/**
* Retrieves the boolean value of a given attribute for the first encountered instance of elementName
*
* @param elem - element to search
* @param elementName - name of element to find
* @param attributeName - name of attribute to retrieve the value of
* @param defaultValue - default value to return if not found
*/
public static boolean readBooleanAttribute(Element elem, String elementName, String attributeName, boolean defaultValue)
{
String val = getAttributeValue(elem, elementName, attributeName);
if (val != null)
{
if (val.equalsIgnoreCase("true") || val.equalsIgnoreCase("false"))
{
//return Boolean.parseBoolean(val);
// needs to be done this way because of JBBUILD-351
return Boolean.valueOf(val);
}
}
return defaultValue;
}
}
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