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/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates and others.
 * All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jakarta.servlet.jsp.el;

import java.beans.FeatureDescriptor;
import java.util.Iterator;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import jakarta.servlet.ServletContext;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.jsp.PageContext;
import jakarta.servlet.jsp.JspContext;

import jakarta.el.PropertyNotWritableException;
import jakarta.el.ELContext;
import jakarta.el.ELResolver;

/**
 * Defines variable resolution behavior for the EL implicit objects defined in the JSP specification.
 * 
 * 

* 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)).
  • *
* * @see jakarta.el.ELResolver * @since JSP 2.1 */ public class ImplicitObjectELResolver extends ELResolver { /** * If the base object is 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. *

* * @param context The context of this evaluation. * @param base Only 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 */ @Override 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. *

* * @param context The context of this evaluation. * @param base Only 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 */ @Override 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. *

* * @param context The context of this evaluation. * @param base Only 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. */ @Override 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. *

* * @param context The context of this evaluation. * @param base Only 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. */ @Override 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: *

*
*
displayName
- The name of the implicit object.
*
name
- Same as displayName property.
*
shortDescription
- A suitable description for the implicit object. Will vary by implementation.
*
expert
- false
*
hidden
- false
*
preferred
- true
*
* In addition, the following named attributes must be set in the returned FeatureDescriptors: *
*
{@link ELResolver#TYPE}
- The runtime type of the implicit object.
*
{@link ELResolver#RESOLVABLE_AT_DESIGN_TIME}
- true.
*
* * @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 An Iterator containing one FeatureDescriptor object for each implicit object, * or null if base is not null. */ @Override public Iterator getFeatureDescriptors(ELContext context, Object base) { ArrayList list = new ArrayList<>(11); // pageContext FeatureDescriptor descriptor = new FeatureDescriptor(); descriptor.setName("pageContext"); descriptor.setDisplayName("pageContext"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", PageContext.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // pageScope descriptor = new FeatureDescriptor(); descriptor.setName("pageScope"); descriptor.setDisplayName("pageScope"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // requestScope descriptor = new FeatureDescriptor(); descriptor.setName("requestScope"); descriptor.setDisplayName("requestScope"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // sessionScope descriptor = new FeatureDescriptor(); descriptor.setName("sessionScope"); descriptor.setDisplayName("sessionScope"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // applicationScope descriptor = new FeatureDescriptor(); descriptor.setName("applicationScope"); descriptor.setDisplayName("applicationScope"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // param descriptor = new FeatureDescriptor(); descriptor.setName("param"); descriptor.setDisplayName("param"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // paramValues descriptor = new FeatureDescriptor(); descriptor.setName("paramValues"); descriptor.setDisplayName("paramValues"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // header descriptor = new FeatureDescriptor(); descriptor.setName("header"); descriptor.setDisplayName("header"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // headerValues descriptor = new FeatureDescriptor(); descriptor.setName("headerValues"); descriptor.setDisplayName("headerValues"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // cookie descriptor = new FeatureDescriptor(); descriptor.setName("cookie"); descriptor.setDisplayName("cookie"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); // initParam descriptor = new FeatureDescriptor(); descriptor.setName("initParam"); descriptor.setDisplayName("initParam"); // descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", Map.class); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); return list.iterator(); } /** * If the base object is null, 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. */ @Override public Class getCommonPropertyType(ELContext context, Object base) { if (base == null) { return String.class; } return null; } // 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 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. static final String sAttributeName = "org.apache.taglibs.standard.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 * * @param pContext The PageContext for which this instance is to be constructed */ public ImplicitObjects(PageContext pContext) { mContext = pContext; } /** * * @param pContext The PageContext for which the ImplicitObjects instance is required * @return 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; } /** * * @return the Map that "wraps" page-scoped attributes */ public Map getPageScopeMap() { if (mPage == null) { mPage = createPageScopeMap(mContext); } return mPage; } /** * * @return the Map that "wraps" request-scoped attributes */ public Map getRequestScopeMap() { if (mRequest == null) { mRequest = createRequestScopeMap(mContext); } return mRequest; } /** * * @return the Map that "wraps" session-scoped attributes */ public Map getSessionScopeMap() { if (mSession == null) { mSession = createSessionScopeMap(mContext); } return mSession; } /** * * @return the Map that "wraps" application-scoped attributes */ public Map getApplicationScopeMap() { if (mApplication == null) { mApplication = createApplicationScopeMap(mContext); } return mApplication; } /** * * @return the Map that maps parameter name to a single parameter values. */ public Map getParamMap() { if (mParam == null) { mParam = createParamMap(mContext); } return mParam; } /** * * @return the Map that maps parameter name to an array of parameter values. */ public Map getParamsMap() { if (mParams == null) { mParams = createParamsMap(mContext); } return mParams; } /** * * @return the Map that maps header name to a single header values. */ public Map getHeaderMap() { if (mHeader == null) { mHeader = createHeaderMap(mContext); } return mHeader; } /** * * @return the Map that maps header name to an array of header values. */ public Map getHeadersMap() { if (mHeaders == null) { mHeaders = createHeadersMap(mContext); } return mHeaders; } /** * * @return the Map that maps init parameter name to a single init parameter values. */ public Map getInitParamMap() { if (mInitParam == null) { mInitParam = createInitParamMap(mContext); } return mInitParam; } /** * * @return 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 * * @param pContext The PageContext for which the Map should be produced * * @return the Map that "wraps" page-scoped attributes */ public static Map createPageScopeMap(PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap() { @Override public Enumeration enumerateKeys() { return context.getAttributeNamesInScope(PageContext.PAGE_SCOPE); } @Override public Object getValue(Object pKey) { if (pKey instanceof String) { return context.getAttribute((String) pKey, PageContext.PAGE_SCOPE); } else { return null; } } @Override public boolean isMutable() { return true; } }; } /** * * Creates the Map that "wraps" request-scoped attributes * * @param pContext The PageContext for which the Map should be produced * * @return the Map that "wraps" request-scoped attributes */ public static Map createRequestScopeMap(PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap() { @Override public Enumeration enumerateKeys() { return context.getAttributeNamesInScope(PageContext.REQUEST_SCOPE); } @Override public Object getValue(Object pKey) { if (pKey instanceof String) { return context.getAttribute((String) pKey, PageContext.REQUEST_SCOPE); } else { return null; } } @Override public boolean isMutable() { return true; } }; } /** * * Creates the Map that "wraps" session-scoped attributes * * @param pContext The PageContext for which the Map should be produced * * @return the Map that "wraps" session-scoped attributes */ public static Map createSessionScopeMap(PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap() { @Override public Enumeration enumerateKeys() { return context.getAttributeNamesInScope(PageContext.SESSION_SCOPE); } @Override public Object getValue(Object pKey) { if (pKey instanceof String) { return context.getAttribute((String) pKey, PageContext.SESSION_SCOPE); } else { return null; } } @Override public boolean isMutable() { return true; } }; } /** * * Creates the Map that "wraps" application-scoped attributes * * @param pContext The PageContext for which the Map should be produced * * @return the Map that "wraps" application-scoped attributes */ public static Map createApplicationScopeMap(PageContext pContext) { final PageContext context = pContext; return new EnumeratedMap() { @Override public Enumeration enumerateKeys() { return context.getAttributeNamesInScope(PageContext.APPLICATION_SCOPE); } @Override public Object getValue(Object pKey) { if (pKey instanceof String) { return context.getAttribute((String) pKey, PageContext.APPLICATION_SCOPE); } else { return null; } } @Override public boolean isMutable() { return true; } }; } /** * * Creates the Map that maps parameter name to single parameter value. * * @param pContext The PageContext for which the Map should be produced * * @return 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() { @Override public Enumeration enumerateKeys() { return request.getParameterNames(); } @Override public String getValue(Object pKey) { if (pKey instanceof String) { return request.getParameter((String) pKey); } else { return null; } } @Override public boolean isMutable() { return false; } }; } /** * * Creates the Map that maps parameter name to an array of parameter values. * * @param pContext The PageContext for which the Map should be produced * * @return 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() { @Override public Enumeration enumerateKeys() { return request.getParameterNames(); } @Override public String[] getValue(Object pKey) { if (pKey instanceof String) { return request.getParameterValues((String) pKey); } else { return null; } } @Override public boolean isMutable() { return false; } }; } /** * * Creates the Map that maps header name to single header value. * * @param pContext The PageContext for which the Map should be produced * * @return 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() { @Override public Enumeration enumerateKeys() { return request.getHeaderNames(); } @Override public String getValue(Object pKey) { if (pKey instanceof String) { return request.getHeader((String) pKey); } else { return null; } } @Override public boolean isMutable() { return false; } }; } /** * * Creates the Map that maps header name to an array of header values. * * @param pContext The PageContext for which the Map should be produced * * @return 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() { @Override public Enumeration enumerateKeys() { return request.getHeaderNames(); } @Override public String[] 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()); } } return l.toArray(new String[l.size()]); } else { return null; } } @Override public boolean isMutable() { return false; } }; } /** * * Creates the Map that maps init parameter name to single init parameter value. * * @param pContext The PageContext for which the Map should be produced * * @return 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() { @Override public Enumeration enumerateKeys() { return context.getInitParameterNames(); } @Override public String getValue(Object pKey) { if (pKey instanceof String) { return context.getInitParameter((String) pKey); } else { return null; } } @Override public boolean isMutable() { return false; } }; } /** * * Creates the Map that maps cookie name to the first matching Cookie in request.getCookies(). * * @param pContext The PageContext for which the Map should be produced * * @return 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; @Override public void clear() { throw new UnsupportedOperationException(); } @Override public boolean containsKey(Object pKey) { return getValue(pKey) != null; } @Override public boolean containsValue(Object pValue) { return getAsMap().containsValue(pValue); } @Override public Set> entrySet() { return getAsMap().entrySet(); } @Override public V get(Object pKey) { return getValue(pKey); } @Override public boolean isEmpty() { return !enumerateKeys().hasMoreElements(); } @Override public Set keySet() { return getAsMap().keySet(); } @Override public V put(K pKey, V pValue) { throw new UnsupportedOperationException(); } @Override public void putAll(Map pMap) { throw new UnsupportedOperationException(); } @Override public V remove(Object pKey) { throw new UnsupportedOperationException(); } @Override public int size() { return getAsMap().size(); } @Override public Collection values() { return getAsMap().values(); } // ------------------------------------- // Abstract methods // ------------------------------------- /** * * @return an enumeration of the keys */ public abstract Enumeration enumerateKeys(); /** * * @return true if it is possible for this data source to change */ public abstract boolean isMutable(); /** * * @param pKey The key for which the value should be obtained * @return the value associated with the given key, or null if not found. */ public abstract V getValue(Object pKey); /** * * Converts the MapSource to a Map. If the map is not mutable, this is cached * * @return A Map created from the source Enumeration */ 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();) { K key = e.nextElement(); V value = getValue(key); ret.put(key, value); } return ret; } } }





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