xpath.java

java1.6众多例子参考

  public XObject execute(
          XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
            throws javax.xml.transform.TransformerException
  {

    xctxt.pushNamespaceContext(namespaceContext);

    xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

    XObject xobj = null;

    try
    {
      xobj = m_mainExp.execute(xctxt);
    }
    catch (TransformerException te)
    {
      te.setLocator(this.getLocator());
      ErrorListener el = xctxt.getErrorListener();
      if(null != el) // defensive, should never happen.
      {
        el.error(te);
      }
      else
        throw te;
    }
    catch (Exception e)
    {
      while (e instanceof com.sun.org.apache.xml.internal.utils.WrappedRuntimeException)
      {
        e = ((com.sun.org.apache.xml.internal.utils.WrappedRuntimeException) e).getException();
      }
      // e.printStackTrace();

      String msg = e.getMessage();
      
      if (msg == null || msg.length() == 0) {
           msg = XSLMessages.createXPATHMessage(
               XPATHErrorResources.ER_XPATH_ERROR, null);
     
      }  
      TransformerException te = new TransformerException(msg,
              getLocator(), e);
      ErrorListener el = xctxt.getErrorListener();
      // te.printStackTrace();
      if(null != el) // defensive, should never happen.
      {
        el.fatalError(te);
      }
      else
        throw te;
    }
    finally
    {
      xctxt.popNamespaceContext();

      xctxt.popCurrentNodeAndExpression();
    }

    return xobj;
  }
  
  /**
   * Given an expression and a context, evaluate the XPath
   * and return the result.
   * 
   * @param xctxt The execution context.
   * @param contextNode The node that "." expresses.
   * @param namespaceContext The context in which namespaces in the
   * XPath are supposed to be expanded.
   * 
   * @throws TransformerException thrown if the active ProblemListener decides
   * the error condition is severe enough to halt processing.
   *
   * @throws javax.xml.transform.TransformerException
   * @xsl.usage experimental
   */
  public boolean bool(
          XPathContext xctxt, int contextNode, PrefixResolver namespaceContext)
            throws javax.xml.transform.TransformerException
  {

    xctxt.pushNamespaceContext(namespaceContext);

    xctxt.pushCurrentNodeAndExpression(contextNode, contextNode);

    try
    {
      return m_mainExp.bool(xctxt);
    }
    catch (TransformerException te)
    {
      te.setLocator(this.getLocator());
      ErrorListener el = xctxt.getErrorListener();
      if(null != el) // defensive, should never happen.
      {
        el.error(te);
      }
      else
        throw te;
    }
    catch (Exception e)
    {
      while (e instanceof com.sun.org.apache.xml.internal.utils.WrappedRuntimeException)
      {
        e = ((com.sun.org.apache.xml.internal.utils.WrappedRuntimeException) e).getException();
      }
      // e.printStackTrace();

      String msg = e.getMessage();
      
      if (msg == null || msg.length() == 0) {
           msg = XSLMessages.createXPATHMessage(
               XPATHErrorResources.ER_XPATH_ERROR, null);
     
      }        
      
      TransformerException te = new TransformerException(msg,
              getLocator(), e);
      ErrorListener el = xctxt.getErrorListener();
      // te.printStackTrace();
      if(null != el) // defensive, should never happen.
      {
        el.fatalError(te);
      }
      else
        throw te;
    }
    finally
    {
      xctxt.popNamespaceContext();

      xctxt.popCurrentNodeAndExpression();
    }

    return false;
  }

  /** Set to true to get diagnostic messages about the result of 
   *  match pattern testing.  */
  private static final boolean DEBUG_MATCHES = false;

  /**
   * Get the match score of the given node.
   *
   * @param xctxt XPath runtime context.
   * @param context The current source tree context node.
   * 
   * @return score, one of {@link #MATCH_SCORE_NODETEST},
   * {@link #MATCH_SCORE_NONE}, {@link #MATCH_SCORE_OTHER}, 
   * or {@link #MATCH_SCORE_QNAME}.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public double getMatchScore(XPathContext xctxt, int context)
          throws javax.xml.transform.TransformerException
  {

    xctxt.pushCurrentNode(context);
    xctxt.pushCurrentExpressionNode(context);

    try
    {
      XObject score = m_mainExp.execute(xctxt);

      if (DEBUG_MATCHES)
      {
        DTM dtm = xctxt.getDTM(context);
        System.out.println("score: " + score.num() + " for "
                           + dtm.getNodeName(context) + " for xpath "
                           + this.getPatternString());
      }

      return score.num();
    }
    finally
    {
      xctxt.popCurrentNode();
      xctxt.popCurrentExpressionNode();
    }

    // return XPath.MATCH_SCORE_NONE;
  }


  /**
   * Warn the user of an problem.
   *
   * @param xctxt The XPath runtime context.
   * @param sourceNode Not used.
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  public void warn(
          XPathContext xctxt, int sourceNode, String msg, Object[] args)
            throws javax.xml.transform.TransformerException
  {

    String fmsg = XSLMessages.createXPATHWarning(msg, args);
    ErrorListener ehandler = xctxt.getErrorListener();

    if (null != ehandler)
    {

      // TO DO: Need to get stylesheet Locator from here.
      ehandler.warning(new TransformerException(fmsg, (SAXSourceLocator)xctxt.getSAXLocator()));
    }
  }

  /**
   * Tell the user of an assertion error, and probably throw an
   * exception.
   *
   * @param b  If false, a runtime exception will be thrown.
   * @param msg The assertion message, which should be informative.
   * 
   * @throws RuntimeException if the b argument is false.
   */
  public void assertion(boolean b, String msg)
  {

    if (!b)
    {
      String fMsg = XSLMessages.createXPATHMessage(
        XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
        new Object[]{ msg });

      throw new RuntimeException(fMsg);
    }
  }

  /**
   * Tell the user of an error, and probably throw an
   * exception.
   *
   * @param xctxt The XPath runtime context.
   * @param sourceNode Not used.
   * @param msg An error msgkey that corresponds to one of the constants found 
   *            in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is 
   *            a key for a format string.
   * @param args An array of arguments represented in the format string, which 
   *             may be null.
   *
   * @throws TransformerException if the current ErrorListoner determines to 
   *                              throw an exception.
   */
  public void error(
          XPathContext xctxt, int sourceNode, String msg, Object[] args)
            throws javax.xml.transform.TransformerException
  {

    String fmsg = XSLMessages.createXPATHMessage(msg, args);
    ErrorListener ehandler = xctxt.getErrorListener();

    if (null != ehandler)
    {
      ehandler.fatalError(new TransformerException(fmsg,
                              (SAXSourceLocator)xctxt.getSAXLocator()));
    }
    else
    {
      SourceLocator slocator = xctxt.getSAXLocator();
      System.out.println(fmsg + "; file " + slocator.getSystemId()
                         + "; line " + slocator.getLineNumber() + "; column "
                         + slocator.getColumnNumber());
    }
  }
  
  /**
   * This will traverse the heararchy, calling the visitor for 
   * each member.  If the called visitor method returns 
   * false, the subtree should not be called.
   * 
   * @param owner The owner of the visitor, where that path may be 
   *              rewritten if needed.
   * @param visitor The visitor whose appropriate method will be called.
   */
  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
  {
  	m_mainExp.callVisitors(this, visitor);
  }

  /**
   * The match score if no match is made.
   * @xsl.usage advanced
   */
  public static final double MATCH_SCORE_NONE = Double.NEGATIVE_INFINITY;

  /**
   * The match score if the pattern has the form
   * of a QName optionally preceded by an @ character.
   * @xsl.usage advanced
   */
  public static final double MATCH_SCORE_QNAME = 0.0;

  /**
   * The match score if the pattern pattern has the form NCName:*.
   * @xsl.usage advanced
   */
  public static final double MATCH_SCORE_NSWILD = -0.25;

  /**
   * The match score if the pattern consists of just a NodeTest.
   * @xsl.usage advanced
   */
  public static final double MATCH_SCORE_NODETEST = -0.5;

  /**
   * The match score if the pattern consists of something
   * other than just a NodeTest or just a qname.
   * @xsl.usage advanced
   */
  public static final double MATCH_SCORE_OTHER = 0.5;
}