xpathutil.java

来自「jakarta-taglibs」· Java 代码 · 共 888 行 · 第 1/3 页

            if (prefix == null || prefix.equals("")) {
                return notNull(
                pageContext.findAttribute(localName),
                prefix,
                localName);
            } else if (prefix.equals(PAGE_P)) {
                return notNull(
                pageContext.getAttribute(localName,PageContext.PAGE_SCOPE),
                prefix,
                localName);
            } else if (prefix.equals(REQUEST_P)) {
                return notNull(
                pageContext.getAttribute(localName,
                PageContext.REQUEST_SCOPE),
                prefix,
                localName);
            } else if (prefix.equals(SESSION_P)) {
                return notNull(
                pageContext.getAttribute(localName,
                PageContext.SESSION_SCOPE),
                prefix,
                localName);
            } else if (prefix.equals(APP_P)) {
                return notNull(
                pageContext.getAttribute(localName,
                PageContext.APPLICATION_SCOPE),
                prefix,
                localName);
            } else if (prefix.equals(PARAM_P)) {
                return notNull(
                pageContext.getRequest().getParameter(localName),
                prefix,
                localName);
            } else if (prefix.equals(INITPARAM_P)) {
                return notNull(
                pageContext.getServletContext().
                getInitParameter(localName),
                prefix,
                localName);
            } else if (prefix.equals(HEADER_P)) {
                HttpServletRequest hsr =
                (HttpServletRequest) pageContext.getRequest();
                return notNull(
                hsr.getHeader(localName),
                prefix,
                localName);
            } else if (prefix.equals(COOKIE_P)) {
                HttpServletRequest hsr =
                (HttpServletRequest) pageContext.getRequest();
                Cookie[] c = hsr.getCookies();
                for (int i = 0; i < c.length; i++)
                    if (c[i].getName().equals(localName))
                        return c[i].getValue();
                throw new UnresolvableException("$" + prefix + ":" + localName);
            } else {
                throw new UnresolvableException("$" + prefix + ":" + localName);
            }
        }    
        
        /**
         * Validate that the Object returned is not null. If it is
         * null, throw an exception.
         */
        private Object notNull(Object o, String prefix, String localName)
        throws UnresolvableException {
            if (o == null) {
                throw new UnresolvableException("$" + (prefix==null?"":prefix+":") + localName);
            }
            //p("resolved to: " + o);
            return o;
        }                
    }
    
    //*********************************************************************
    // Support for XPath evaluation
    
    private PageContext pageContext;
    private static HashMap exprCache;
    private static JSTLPrefixResolver jstlPrefixResolver = null;
    
    /** Initialize globally useful data. */
    private synchronized static void staticInit() {
        if (jstlPrefixResolver == null) {
            // register supported namespaces
            jstlPrefixResolver = new JSTLPrefixResolver();
            jstlPrefixResolver.addNamespace("pageScope", PAGE_NS_URL);
            jstlPrefixResolver.addNamespace("requestScope", REQUEST_NS_URL);
            jstlPrefixResolver.addNamespace("sessionScope", SESSION_NS_URL);
            jstlPrefixResolver.addNamespace("applicationScope", APP_NS_URL);
            jstlPrefixResolver.addNamespace("param", PARAM_NS_URL);
            jstlPrefixResolver.addNamespace("initParam", INITPARAM_NS_URL);
            jstlPrefixResolver.addNamespace("header", HEADER_NS_URL);
            jstlPrefixResolver.addNamespace("cookie", COOKIE_NS_URL);
            
            
            // create a HashMap to cache the expressions
            exprCache = new HashMap();
        }
    }
    
    static DocumentBuilderFactory dbf = null;
    static DocumentBuilder db = null;
    static Document d = null;
    
    static Document getDummyDocument( ) {
        try {
            if ( dbf == null ) {
                dbf = DocumentBuilderFactory.newInstance();
                dbf.setNamespaceAware( true );
                dbf.setValidating( false );
            }
            db = dbf.newDocumentBuilder();

            DOMImplementation dim = db.getDOMImplementation();
            d = dim.createDocument("http://java.sun.com/jstl", "dummyroot", null); 
            //d = db.newDocument();
            return d;
        } catch ( Exception e ) {
            e.printStackTrace();
        }
        return null;
    }

     static Document getDummyDocumentWithoutRoot( ) {
        try {
            if ( dbf == null ) {
                dbf = DocumentBuilderFactory.newInstance();
                dbf.setNamespaceAware( true );
                dbf.setValidating( false );
            }
            db = dbf.newDocumentBuilder();

            d = db.newDocument();
            return d;
        } catch ( Exception e ) {
            e.printStackTrace();
        }
        return null;
    }

    private static Document getDocumentForNode(Node node) {
        Document doc = getDummyDocumentWithoutRoot();
        Node importedNode = doc.importNode(node, true);
        doc.appendChild(importedNode);
        return doc;
    }
    
    // The following variable is used for holding the modified xpath string
    // when adapting parameter for Xalan XPath engine, where we need to have
    // a Non null context node.
    String modifiedXPath = null;
    

    
    
    
    /**
     * Evaluate an XPath expression to a String value. 
     */
    public String valueOf(Node n, String xpath) throws JspTagException  {
        //p("******** valueOf(" + n + ", " + xpath + ")");
        staticInit();
        // @@@ but where do we set the Pag4eContext for the varaiblecontext?
        JstlVariableContext vs = new JstlVariableContext();
        XPathContext xpathSupport = new XPathContext();
        xpathSupport.setVarStack( vs);
        
        Vector varVector = fillVarStack(vs, xpathSupport);                
        
        Node contextNode = adaptParamsForXalan( vs, n, xpath.trim() );
        
        xpath = modifiedXPath;
        
        //p("******** valueOf: modified xpath: " + xpath);

        XObject result = JSTLXPathAPI.eval( contextNode, xpath,
        jstlPrefixResolver,xpathSupport, varVector);

        
        //p("******Result TYPE => " + result.getTypeString() );
        
        String resultString = result.str();
        //p("******** valueOf: after eval: " + resultString);
        
        return resultString;
    
    }    

    /** 
     * Evaluate an XPath expression to a boolean value. 
     */
    public boolean booleanValueOf(Node n, String xpath)
    throws JspTagException {
        
        staticInit();
        JstlVariableContext vs = new JstlVariableContext();
        XPathContext xpathSupport = new XPathContext();
        xpathSupport.setVarStack( vs);
        
        Vector varVector = fillVarStack(vs, xpathSupport);        
        
        Node contextNode = adaptParamsForXalan( vs, n, xpath.trim() );
        xpath = modifiedXPath;
        
        XObject result = JSTLXPathAPI.eval( contextNode, xpath,
        jstlPrefixResolver, xpathSupport, varVector);
        
        try {
            return result.bool();
        } catch (TransformerException ex) {
            throw new JspTagException(
                Resources.getMessage("XPATH_ERROR_XOBJECT", ex.toString()), ex);            
        }
    }
    
    /** 
     * Evaluate an XPath expression to a List of nodes. 
     */
    public List selectNodes(Node n, String xpath)  throws JspTagException {
        
        staticInit();
        JstlVariableContext vs = new JstlVariableContext();
        XPathContext xpathSupport = new XPathContext();
        xpathSupport.setVarStack( vs);
        
        Vector varVector = fillVarStack(vs, xpathSupport);                

        Node contextNode = adaptParamsForXalan( vs, n, xpath.trim() );
        xpath = modifiedXPath;
        
        XObject result = JSTLXPathAPI.eval( contextNode, xpath,
        jstlPrefixResolver,xpathSupport, varVector);
        try {
            NodeList nl= JSTLXPathAPI.getNodeList(result);
            return new JSTLNodeList( nl );
        } catch ( JspTagException e ) {
            try { 
                //If result can't be converted to NodeList we receive exception
                // In this case we may have single primitive value as the result
                // Populating List with this value ( String, Boolean or Number )

                //System.out.println("JSTLXPathAPI.getNodeList thrown exception:"+ e);
                Vector vector = new Vector();
                Object resultObject = null;
                if ( result.getType()== XObject.CLASS_BOOLEAN ) {
                    resultObject = new Boolean( result.bool());
                } else if ( result.getType()== XObject.CLASS_NUMBER ) {
                    resultObject = new Double( result.num());
                } else if ( result.getType()== XObject.CLASS_STRING ) {
                    resultObject = result.str();
                }

                vector.add( resultObject );
                return new JSTLNodeList ( vector );
            } catch ( TransformerException te ) {
                throw new JspTagException(te.toString(), te);
            }
        }
          
        
       
    }
    
    /** 
     * Evaluate an XPath expression to a single node. 
     */
    public Node selectSingleNode(Node n, String xpath)
    throws JspTagException {
        //p("selectSingleNode of XPathUtil = passed node:" +
        //   "xpath => " + n + " : " + xpath );
        
        staticInit();
        JstlVariableContext vs = new JstlVariableContext();
        XPathContext xpathSupport = new XPathContext();
        xpathSupport.setVarStack( vs);
        
        Vector varVector = fillVarStack(vs, xpathSupport);                

        Node contextNode = adaptParamsForXalan( vs, n, xpath.trim() );
        xpath = modifiedXPath;
        
        return (Node) JSTLXPathAPI.selectSingleNode( contextNode, xpath,
        jstlPrefixResolver,xpathSupport );
    }
    
    /** Returns a locally appropriate context given a node. */
    private VariableStack getLocalContext() {
        // set up instance-specific contexts
        VariableStack vc = new JstlVariableContext();
        return vc;
    }    
    
    //*********************************************************************
    // Adapt XPath expression for integration with Xalan
   
    /**