The following variables are resolved by this ELResolver,
* as per the JSP specification:
*
pageContext - the PageContext object.pageScope - a Map that maps page-scoped
* attribute names to their values.requestScope - a Map that maps
* request-scoped attribute names to their values.sessionScope - a Map that maps
* session-scoped attribute names to their values.applicationScope - a Map that maps
* application-scoped attribute names to their values.param - a Map that maps parameter
* names to a single String parameter value (obtained by calling
* ServletRequest.getParameter(String name)).paramValues - a Map that maps parameter
* names to a String[] of all values for that
* parameter (obtained by calling
* ServletRequest.getParameterValues(String name)).header - a Map that maps header names
* to a single String header value (obtained by calling
* HttpServletRequest.getHeader(String name)).headerValues - a Map that maps header
* names to a String[] of all values for that header
* (obtained by calling
* HttpServletRequest.getHeaders(String)).cookie - a Map that maps cookie names
* to a single Cookie object. Cookies are retrieved
* according to the semantics of
* HttpServletRequest.getCookies(). If the same name
* is shared by multiple cookies, an implementation must use the
* first one encountered in the array of Cookie objects
* returned by the getCookies() method. However, users
* of the cookie implicit object must be aware that the ordering
* of cookies is currently unspecified in the servlet
* specification.initParam - a Map that maps context
* initialization parameter names to their String parameter
* value (obtained by calling
* ServletContext.getInitParameter(String name)).null, and the property matches
* the name of a JSP implicit object, returns the implicit object.
*
* The propertyResolved property of the
* ELContext object must be set to true by
* this resolver before returning if an implicit object is matched. If
* this property is not true after this method is called,
* the caller should ignore the return value.
null is handled by this resolver.
* Other values will result in an immediate return.
* @param property The name of the implicit object to resolve.
* @return If the propertyResolved property of
* ELContext was set to true, then
* the implicit object; otherwise undefined.
* @throws NullPointerException if context is null
* @throws ELException if an exception was thrown while performing
* the property or variable resolution. The thrown exception
* must be included as the cause property of this exception, if
* available.
*/
public Object getValue(ELContext context,
Object base,
Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base != null) {
return null;
}
PageContext ctxt = (PageContext)context.getContext(JspContext.class);
if ("pageContext".equals(property)) {
context.setPropertyResolved(true);
return ctxt;
}
ImplicitObjects implicitObjects =
ImplicitObjects.getImplicitObjects(ctxt);
if ("pageScope".equals(property)) {
context.setPropertyResolved(true);
return implicitObjects.getPageScopeMap();
}
if ("requestScope".equals(property)) {
context.setPropertyResolved(true);
return implicitObjects.getRequestScopeMap();
}
if ("sessionScope".equals(property)) {
context.setPropertyResolved(true);
return implicitObjects.getSessionScopeMap();
}
if ("applicationScope".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getApplicationScopeMap ();
}
if ("param".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getParamMap();
}
if ("paramValues".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getParamsMap();
}
if ("header".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getHeaderMap();
}
if ("headerValues".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getHeadersMap();
}
if ("initParam".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getInitParamMap ();
}
if ("cookie".equals (property)) {
context.setPropertyResolved(true);
return implicitObjects.getCookieMap ();
}
return null;
}
/**
* If the base object is null, and the property matches
* the name of a JSP implicit object, returns null to
* indicate that no types are ever accepted to setValue().
*
* The propertyResolved property of the
* ELContext object must be set to true by
* this resolver before returning if an implicit object is matched. If
* this property is not true after this method is called,
* the caller should ignore the return value.
null is handled by this resolver.
* Other values will result in an immediate return.
* @param property The name of the implicit object to resolve.
* @return If the propertyResolved property of
* ELContext was set to true, then
* null; otherwise undefined.
* @throws NullPointerException if context is null
* @throws ELException if an exception was thrown while performing
* the property or variable resolution. The thrown exception
* must be included as the cause property of this exception, if
* available.
*/
public Class getType(ELContext context,
Object base,
Object property) {
if (context == null) {
throw new NullPointerException();
}
if ((base == null) && ("pageContext".equals(property) ||
"pageScope".equals(property)) ||
"requestScope".equals(property) ||
"sessionScope".equals(property) ||
"applicationScope".equals (property) ||
"param".equals (property) ||
"paramValues".equals (property) ||
"header".equals (property) ||
"headerValues".equals (property) ||
"initParam".equals (property) ||
"cookie".equals (property)) {
context.setPropertyResolved(true);
}
return null;
}
/**
* If the base object is null, and the property matches
* the name of a JSP implicit object, throws
* PropertyNotWritableException to indicate that implicit
* objects cannot be overwritten.
*
* The propertyResolved property of the
* ELContext object must be set to true by
* this resolver before returning if an implicit object is matched. If
* this property is not true after this method is called,
* the caller should ignore the return value.
null is handled by this resolver.
* Other values will result in an immediate return.
* @param property The name of the implicit object.
* @param val The value to be associated with the implicit object.
* @throws NullPointerException if context is null.
* @throws PropertyNotWritableException always thrown, if the
* implicit object name is recognized by this resolver.
* @throws ELException if an exception was thrown while performing
* the property or variable resolution. The thrown exception
* must be included as the cause property of this exception, if
* available.
*/
public void setValue(ELContext context,
Object base,
Object property,
Object val) {
if (context == null) {
throw new NullPointerException();
}
if ((base == null) && ("pageContext".equals(property) ||
"pageScope".equals(property)) ||
"requestScope".equals(property) ||
"sessionScope".equals(property) ||
"applicationScope".equals (property) ||
"param".equals (property) ||
"paramValues".equals (property) ||
"header".equals (property) ||
"headerValues".equals (property) ||
"initParam".equals (property) ||
"cookie".equals (property)) {
throw new PropertyNotWritableException();
}
}
/**
* If the base object is null, and the property matches
* the name of a JSP implicit object, returns true
* to indicate that implicit objects cannot be overwritten.
*
* The propertyResolved property of the
* ELContext object must be set to true by
* this resolver before returning if an implicit object is matched. If
* this property is not true after this method is called,
* the caller should ignore the return value.
null is handled by this resolver.
* Other values will result in an immediate return.
* @param property The name of the implicit object.
* @return If the propertyResolved property of
* ELContext was set to true, then
* true; otherwise undefined.
* @throws NullPointerException if context is null.
* @throws ELException if an exception was thrown while performing
* the property or variable resolution. The thrown exception
* must be included as the cause property of this exception, if
* available.
*/
public boolean isReadOnly(ELContext context,
Object base,
Object property) {
if (context == null) {
throw new NullPointerException();
}
if ((base == null) && ("pageContext".equals(property) ||
"pageScope".equals(property)) ||
"requestScope".equals(property) ||
"sessionScope".equals(property) ||
"applicationScope".equals (property) ||
"param".equals (property) ||
"paramValues".equals (property) ||
"header".equals (property) ||
"headerValues".equals (property) ||
"initParam".equals (property) ||
"cookie".equals (property)) {
context.setPropertyResolved(true);
return true;
}
return false; // Doesn't matter
}
/**
* If the base object is null, and the property matches
* the name of a JSP implicit object, returns an Iterator
* containing FeatureDescriptor objects with information
* about each JSP implicit object resolved by this resolver. Otherwise,
* returns null.
*
* The Iterator returned must contain one instance of
* {@link java.beans.FeatureDescriptor} for each of the EL implicit objects
* defined by the JSP spec. Each info object contains information about
* a single implicit object, and is initialized as follows:
*
falsefalsetrueFeatureDescriptors:
* true.null is handled by this resolver.
* Other values will result in a null return value.
* @return An Iterator containing one
* FeatureDescriptor object for each implicit object, or
* null if base is not null.
*/
public Iteratornull, returns
* String.class. Otherwise, returns null.
*
* @param context The context of this evaluation.
* @param base Only null is handled by this resolver.
* Other values will result in a null return value.
* @return null if base is not null; otherwise
* String.class.
*/
public ClassThis class is used to generate the implicit Map and List objects * that wrap various elements of the PageContext. It also returns the * correct implicit object for a given implicit object name. * * @author Nathan Abramson - Art Technology Group **/ private static class ImplicitObjects { //------------------------------------- // Constants //------------------------------------- // XXX - This probably needs to change, now that this is in a // standard pkg. // Yes this has to move as it is breaking the spring tags or changing the value of the string sAttributeName // from org.apache.taglibs.standard.ImplicitObjects to org.apache.taglibs.standard.jsp.ImplicitObjects static final String sAttributeName = "org.apache.taglibs.standard.jsp.ImplicitObjects"; //------------------------------------- // Member variables //------------------------------------- PageContext mContext; Map mPage; Map mRequest; Map mSession; Map mApplication; Map mParam; Map mParams; Map mHeader; Map mHeaders; Map mInitParam; Map mCookie; //------------------------------------- /** * * Constructor **/ public ImplicitObjects (PageContext pContext) { mContext = pContext; } //------------------------------------- /** * * Finds the ImplicitObjects associated with the PageContext, * creating it if it doesn't yet exist. **/ public static ImplicitObjects getImplicitObjects (PageContext pContext) { ImplicitObjects objs = (ImplicitObjects) pContext.getAttribute (sAttributeName, PageContext.PAGE_SCOPE); if (objs == null) { objs = new ImplicitObjects (pContext); pContext.setAttribute (sAttributeName, objs, PageContext.PAGE_SCOPE); } return objs; } //------------------------------------- /** * * Returns the Map that "wraps" page-scoped attributes **/ public Map getPageScopeMap () { if (mPage == null) { mPage = createPageScopeMap (mContext); } return mPage; } //------------------------------------- /** * * Returns the Map that "wraps" request-scoped attributes **/ public Map getRequestScopeMap () { if (mRequest == null) { mRequest = createRequestScopeMap (mContext); } return mRequest; } //------------------------------------- /** * * Returns the Map that "wraps" session-scoped attributes **/ public Map getSessionScopeMap () { if (mSession == null) { mSession = createSessionScopeMap (mContext); } return mSession; } //------------------------------------- /** * * Returns the Map that "wraps" application-scoped attributes **/ public Map getApplicationScopeMap () { if (mApplication == null) { mApplication = createApplicationScopeMap (mContext); } return mApplication; } //------------------------------------- /** * * Returns the Map that maps parameter name to a single parameter * values. **/ public Map getParamMap () { if (mParam == null) { mParam = createParamMap (mContext); } return mParam; } //------------------------------------- /** * * Returns the Map that maps parameter name to an array of parameter * values. **/ public Map getParamsMap () { if (mParams == null) { mParams = createParamsMap (mContext); } return mParams; } //------------------------------------- /** * * Returns the Map that maps header name to a single header * values. **/ public Map getHeaderMap () { if (mHeader == null) { mHeader = createHeaderMap (mContext); } return mHeader; } //------------------------------------- /** * * Returns the Map that maps header name to an array of header * values. **/ public Map getHeadersMap () { if (mHeaders == null) { mHeaders = createHeadersMap (mContext); } return mHeaders; } //------------------------------------- /** * * Returns the Map that maps init parameter name to a single init * parameter values. **/ public Map getInitParamMap () { if (mInitParam == null) { mInitParam = createInitParamMap (mContext); } return mInitParam; } //------------------------------------- /** * * Returns the Map that maps cookie name to the first matching * Cookie in request.getCookies(). **/ public Map getCookieMap () { if (mCookie == null) { mCookie = createCookieMap (mContext); } return mCookie; } //------------------------------------- // Methods for generating wrapper maps //------------------------------------- /** * * Creates the Map that "wraps" page-scoped attributes **/ public static Map createPageScopeMap (PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap () { public Enumeration enumerateKeys () { return context.getAttributeNamesInScope (PageContext.PAGE_SCOPE); } public Object getValue (Object pKey) { if (pKey instanceof String) { return context.getAttribute ((String) pKey, PageContext.PAGE_SCOPE); } else { return null; } } public boolean isMutable () { return true; } }; } //------------------------------------- /** * * Creates the Map that "wraps" request-scoped attributes **/ public static Map createRequestScopeMap (PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap () { public Enumeration enumerateKeys () { return context.getAttributeNamesInScope (PageContext.REQUEST_SCOPE); } public Object getValue (Object pKey) { if (pKey instanceof String) { return context.getAttribute ((String) pKey, PageContext.REQUEST_SCOPE); } else { return null; } } public boolean isMutable () { return true; } }; } //------------------------------------- /** * * Creates the Map that "wraps" session-scoped attributes **/ public static Map createSessionScopeMap (PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap () { public Enumeration enumerateKeys () { return context.getAttributeNamesInScope (PageContext.SESSION_SCOPE); } public Object getValue (Object pKey) { if (pKey instanceof String) { return context.getAttribute ((String) pKey, PageContext.SESSION_SCOPE); } else { return null; } } public boolean isMutable () { return true; } }; } //------------------------------------- /** * * Creates the Map that "wraps" application-scoped attributes **/ public static Map createApplicationScopeMap (PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap () { public Enumeration enumerateKeys () { return context.getAttributeNamesInScope (PageContext.APPLICATION_SCOPE); } public Object getValue (Object pKey) { if (pKey instanceof String) { return context.getAttribute ((String) pKey, PageContext.APPLICATION_SCOPE); } else { return null; } } public boolean isMutable () { return true; } }; } //------------------------------------- /** * * Creates the Map that maps parameter name to single parameter * value. **/ public static Map createParamMap (PageContext pContext) { final HttpServletRequest request = (HttpServletRequest) pContext.getRequest (); return new EnumeratedMap () { public Enumeration enumerateKeys () { return request.getParameterNames (); } public Object getValue (Object pKey) { if (pKey instanceof String) { return request.getParameter ((String) pKey); } else { return null; } } public boolean isMutable () { return false; } }; } //------------------------------------- /** * * Creates the Map that maps parameter name to an array of parameter * values. **/ public static Map createParamsMap (PageContext pContext) { final HttpServletRequest request = (HttpServletRequest) pContext.getRequest (); return new EnumeratedMap () { public Enumeration enumerateKeys () { return request.getParameterNames (); } public Object getValue (Object pKey) { if (pKey instanceof String) { return request.getParameterValues ((String) pKey); } else { return null; } } public boolean isMutable () { return false; } }; } //------------------------------------- /** * * Creates the Map that maps header name to single header * value. **/ public static Map createHeaderMap (PageContext pContext) { final HttpServletRequest request = (HttpServletRequest) pContext.getRequest (); return new EnumeratedMap () { public Enumeration enumerateKeys () { return request.getHeaderNames (); } public Object getValue (Object pKey) { if (pKey instanceof String) { return request.getHeader ((String) pKey); } else { return null; } } public boolean isMutable () { return false; } }; } //------------------------------------- /** * * Creates the Map that maps header name to an array of header * values. **/ public static Map createHeadersMap (PageContext pContext) { final HttpServletRequest request = (HttpServletRequest) pContext.getRequest (); return new EnumeratedMap () { public Enumeration enumerateKeys () { return request.getHeaderNames (); } public Object getValue (Object pKey) { if (pKey instanceof String) { // Drain the header enumeration List l = new ArrayList (); Enumeration e = request.getHeaders ((String) pKey); if (e != null) { while (e.hasMoreElements ()) { l.add (e.nextElement ()); } } String [] ret = (String []) l.toArray (new String [l.size ()]); return ret; } else { return null; } } public boolean isMutable () { return false; } }; } //------------------------------------- /** * * Creates the Map that maps init parameter name to single init * parameter value. **/ public static Map createInitParamMap (PageContext pContext) { final ServletContext context = pContext.getServletContext (); return new EnumeratedMap () { public Enumeration enumerateKeys () { return context.getInitParameterNames (); } public Object getValue (Object pKey) { if (pKey instanceof String) { return context.getInitParameter ((String) pKey); } else { return null; } } public boolean isMutable () { return false; } }; } //------------------------------------- /** * * Creates the Map that maps cookie name to the first matching * Cookie in request.getCookies(). **/ public static Map createCookieMap (PageContext pContext) { // Read all the cookies and construct the entire map HttpServletRequest request = (HttpServletRequest) pContext.getRequest (); Cookie [] cookies = request.getCookies (); Map ret = new HashMap (); for (int i = 0; cookies != null && i < cookies.length; i++) { Cookie cookie = cookies [i]; if (cookie != null) { String name = cookie.getName (); if (!ret.containsKey (name)) { ret.put (name, cookie); } } } return ret; } //------------------------------------- } // XXX - I moved this class from commons-el to an inner class here // so that we do not have a dependency from the JSP APIs into commons-el. // There might be a better way to do this. /** *
This is a Map implementation driven by a data source that only * provides an enumeration of keys and a getValue(key) method. This * class must be subclassed to implement those methods. * *
Some of the methods may incur a performance penalty that * involves enumerating the entire data source. In these cases, the * Map will try to save the results of that enumeration, but only if * the underlying data source is immutable. * * @author Nathan Abramson - Art Technology Group **/ private static abstract class EnumeratedMap implements Map { //------------------------------------- // Member variables //------------------------------------- Map mMap; //------------------------------------- public void clear () { throw new UnsupportedOperationException (); } //------------------------------------- public boolean containsKey (Object pKey) { return getValue (pKey) != null; } //------------------------------------- public boolean containsValue (Object pValue) { return getAsMap ().containsValue (pValue); } //------------------------------------- public Set entrySet () { return getAsMap ().entrySet (); } //------------------------------------- public Object get (Object pKey) { return getValue (pKey); } //------------------------------------- public boolean isEmpty () { return !enumerateKeys ().hasMoreElements (); } //------------------------------------- public Set keySet () { return getAsMap ().keySet (); } //------------------------------------- public Object put (Object pKey, Object pValue) { throw new UnsupportedOperationException (); } //------------------------------------- public void putAll (Map pMap) { throw new UnsupportedOperationException (); } //------------------------------------- public Object remove (Object pKey) { throw new UnsupportedOperationException (); } //------------------------------------- public int size () { return getAsMap ().size (); } //------------------------------------- public Collection values () { return getAsMap ().values (); } //------------------------------------- // Abstract methods //------------------------------------- /** * * Returns an enumeration of the keys **/ public abstract Enumeration enumerateKeys (); //------------------------------------- /** * * Returns true if it is possible for this data source to change **/ public abstract boolean isMutable (); //------------------------------------- /** * * Returns the value associated with the given key, or null if not * found. **/ public abstract Object getValue (Object pKey); //------------------------------------- /** * * Converts the MapSource to a Map. If the map is not mutable, this * is cached **/ public Map getAsMap () { if (mMap != null) { return mMap; } else { Map m = convertToMap (); if (!isMutable ()) { mMap = m; } return m; } } //------------------------------------- /** * * Converts to a Map **/ Map convertToMap () { Map ret = new HashMap (); for (Enumeration e = enumerateKeys (); e.hasMoreElements (); ) { Object key = e.nextElement (); Object value = getValue (key); ret.put (key, value); } return ret; } //------------------------------------- } }