com.google.code.facebookapi.XmlHelper Maven / Gradle / Ivy
package com.google.code.facebookapi;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
public class XmlHelper {
/**
* Prints out the DOM tree.
*
* @param n
* the parent node to start printing from
* @param prefix
* string to append to output, should not be null
*/
public static void printDom( Node n, String prefix, StringBuilder sb ) {
String outString = prefix;
if ( n.getNodeType() == Node.TEXT_NODE ) {
outString += "'" + n.getTextContent().trim() + "'";
} else {
outString += n.getNodeName();
}
sb.append( outString );
sb.append( "\n" );
NodeList children = n.getChildNodes();
int length = children.getLength();
for ( int i = 0; i < length; i++ ) {
printDom( children.item( i ), prefix + " ", sb );
}
}
/**
* Extracts a String from a Document consisting entirely of a String.
*
* @return the String
*/
public static String extractString( Node d ) {
if ( d == null ) {
return null;
}
return d.getFirstChild().getTextContent();
}
/**
* Extracts an Integer from a document that consists of an Integer only.
*
* @param doc
* @return the Integer
*/
public static int extractInt( Node doc ) {
if ( doc == null ) {
return 0;
}
return Integer.parseInt( doc.getFirstChild().getTextContent() );
}
/**
* Extracts a Long from a document that consists of a Long only.
*
* @param doc
* @return the Long
*/
public static Long extractLong( Node doc ) {
if ( doc == null ) {
return 0l;
}
return Long.parseLong( doc.getFirstChild().getTextContent() );
}
/**
* Extracts a Boolean from a result that consists of a Boolean only.
*
* @param result
* @return the Boolean
*/
public static boolean extractBoolean( Node result ) {
if ( result == null ) {
return false;
}
return 1 == extractInt( result );
}
public static Document parseCallResult( Object rawResponse, DocumentBuilderFactory factory ) throws FacebookException {
if ( rawResponse == null ) {
return null;
}
try {
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse( new InputSource( new StringReader( (String) rawResponse ) ) );
doc.normalizeDocument();
stripEmptyTextNodes( doc );
return parseCallResult( doc );
}
catch ( ParserConfigurationException ex ) {
throw new RuntimeException( "Trouble configuring XML Parser", ex );
}
catch ( SAXException ex ) {
throw new RuntimeException( "Trouble parsing XML from facebook", ex );
}
catch ( IOException ex ) {
throw new RuntimeException( "Trouble parsing XML from facebook", ex );
}
}
/**
* Hack...since DOM reads newlines as textnodes we want to strip out those nodes to make it easier to use the tree.
*/
public static void stripEmptyTextNodes( Node n ) {
NodeList children = n.getChildNodes();
int length = children.getLength();
for ( int i = 0; i < length; i++ ) {
Node c = children.item( i );
if ( !c.hasChildNodes() && c.getNodeType() == Node.TEXT_NODE && c.getTextContent().trim().length() == 0 ) {
n.removeChild( c );
i-- ;
length-- ;
children = n.getChildNodes();
} else {
stripEmptyTextNodes( c );
}
}
}
/**
* Used in the context of optimisation. If we already have an XML snippet, it's not sensible to convert it to a string and then convert it back to a document.
*
* @param doc
* @return
* @throws FacebookException
*/
public static Document parseCallResult( Document doc ) throws FacebookException {
NodeList errors = doc.getElementsByTagName( IFacebookRestClient.ERROR_TAG );
if ( errors.getLength() > 0 ) {
int errorCode = Integer.parseInt( errors.item( 0 ).getFirstChild().getFirstChild().getTextContent() );
String message = errors.item( 0 ).getFirstChild().getNextSibling().getTextContent();
throw new FacebookException( errorCode, message );
}
return doc;
}
}