Tomcat example source code file (ImplicitObjectELResolver.java)

This example Tomcat source code file (ImplicitObjectELResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

bean, cookie, enumeration, enumeration, http, httpservletrequest, map, map, nullpointerexception, object, object, pagecontext, request, response, scopemanager, scopemap, scopemap, servlet, string, util

The Tomcat ImplicitObjectELResolver.java source code

/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 javax.servlet.jsp.el;

import java.beans.FeatureDescriptor;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Vector;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.PropertyNotFoundException;
import javax.el.PropertyNotWritableException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.PageContext;

/**
 *
 * @since 2.1
 */
public class ImplicitObjectELResolver extends ELResolver {

    private final static String[] SCOPE_NAMES = new String[] {
            "applicationScope", "cookie", "header", "headerValues",
            "initParam", "pageContext", "pageScope", "param", "paramValues",
            "requestScope", "sessionScope" };

    private final static int APPLICATIONSCOPE = 0;

    private final static int COOKIE = 1;

    private final static int HEADER = 2;

    private final static int HEADERVALUES = 3;

    private final static int INITPARAM = 4;

    private final static int PAGECONTEXT = 5;

    private final static int PAGESCOPE = 6;

    private final static int PARAM = 7;

    private final static int PARAM_VALUES = 8;

    private final static int REQUEST_SCOPE = 9;

    private final static int SESSION_SCOPE = 10;

    public ImplicitObjectELResolver() {
        super();
    }

    public Object getValue(ELContext context, Object base, Object property)
            throws NullPointerException, PropertyNotFoundException, ELException {
        if (context == null) {
            throw new NullPointerException();
        }

        if (base == null && property != null) {
            int idx = Arrays.binarySearch(SCOPE_NAMES, property.toString());

            if (idx >= 0) {
                PageContext page = (PageContext) context
                        .getContext(JspContext.class);
                context.setPropertyResolved(true);
                switch (idx) {
                case APPLICATIONSCOPE:
                    return ScopeManager.get(page).getApplicationScope();
                case COOKIE:
                    return ScopeManager.get(page).getCookie();
                case HEADER:
                    return ScopeManager.get(page).getHeader();
                case HEADERVALUES:
                    return ScopeManager.get(page).getHeaderValues();
                case INITPARAM:
                    return ScopeManager.get(page).getInitParam();
                case PAGECONTEXT:
                    return ScopeManager.get(page).getPageContext();
                case PAGESCOPE:
                    return ScopeManager.get(page).getPageScope();
                case PARAM:
                    return ScopeManager.get(page).getParam();
                case PARAM_VALUES:
                    return ScopeManager.get(page).getParamValues();
                case REQUEST_SCOPE:
                    return ScopeManager.get(page).getRequestScope();
                case SESSION_SCOPE:
                    return ScopeManager.get(page).getSessionScope();
                }
            }
        }
        return null;
    }

    public Class getType(ELContext context, Object base, Object property)
            throws NullPointerException, PropertyNotFoundException, ELException {
        if (context == null) {
            throw new NullPointerException();
        }

        if (base == null && property != null) {
            int idx = Arrays.binarySearch(SCOPE_NAMES, property.toString());
            if (idx >= 0) {
                context.setPropertyResolved(true);
            }
        }
        return null;
    }

    public void setValue(ELContext context, Object base, Object property,
            Object value) throws NullPointerException,
            PropertyNotFoundException, PropertyNotWritableException,
            ELException {
        if (context == null) {
            throw new NullPointerException();
        }

        if (base == null && property != null) {
            int idx = Arrays.binarySearch(SCOPE_NAMES, property.toString());
            if (idx >= 0) {
                context.setPropertyResolved(true);
                throw new PropertyNotWritableException();
            }
        }
    }

    public boolean isReadOnly(ELContext context, Object base, Object property)
            throws NullPointerException, PropertyNotFoundException, ELException {
        if (context == null) {
            throw new NullPointerException();
        }

        if (base == null && property != null) {
            int idx = Arrays.binarySearch(SCOPE_NAMES, property.toString());
            if (idx >= 0) {
                context.setPropertyResolved(true);
                return true;
            }
        }
        return false;
    }

    public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
        List<FeatureDescriptor> feats = new ArrayList(
                SCOPE_NAMES.length);
        FeatureDescriptor feat;
        for (int i = 0; i < SCOPE_NAMES.length; i++) {
            feat = new FeatureDescriptor();
            feat.setDisplayName(SCOPE_NAMES[i]);
            feat.setExpert(false);
            feat.setHidden(false);
            feat.setName(SCOPE_NAMES[i]);
            feat.setPreferred(true);
            feat.setValue(RESOLVABLE_AT_DESIGN_TIME, Boolean.TRUE);
            feat.setValue(TYPE, String.class);
            feats.add(feat);
        }
        return feats.iterator();
    }

    public Class<String> getCommonPropertyType(ELContext context, Object base) {
        if (base == null) {
            return String.class;
        }
        return null;
    }

    private static class ScopeManager {
        private final static String MNGR_KEY = ScopeManager.class.getName();

        private final PageContext page;

        private Map applicationScope;

        private Map cookie;

        private Map header;

        private Map headerValues;

        private Map initParam;

        private Map pageScope;

        private Map param;

        private Map paramValues;

        private Map requestScope;

        private Map sessionScope;

        public ScopeManager(PageContext page) {
            this.page = page;
        }

        public static ScopeManager get(PageContext page) {
            ScopeManager mngr = (ScopeManager) page.getAttribute(MNGR_KEY);
            if (mngr == null) {
                mngr = new ScopeManager(page);
                page.setAttribute(MNGR_KEY, mngr);
            }
            return mngr;
        }

        public Map getApplicationScope() {
            if (this.applicationScope == null) {
                this.applicationScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        page.getServletContext().setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        page.getServletContext().removeAttribute(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page.getServletContext().getAttributeNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getServletContext().getAttribute(name);
                    }
                };
            }
            return this.applicationScope;
        }

        public Map getCookie() {
            if (this.cookie == null) {
                this.cookie = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        Cookie[] c = ((HttpServletRequest) page.getRequest())
                                .getCookies();
                        if (c != null) {
                            Vector v = new Vector();
                            for (int i = 0; i < c.length; i++) {
                                v.add(c[i].getName());
                            }
                            return v.elements();
                        }
                        return null;
                    }

                    protected Object getAttribute(String name) {
                        Cookie[] c = ((HttpServletRequest) page.getRequest())
                                .getCookies();
                        if (c != null) {
                            for (int i = 0; i < c.length; i++) {
                                if (name.equals(c[i].getName())) {
                                    return c[i];
                                }
                            }
                        }
                        return null;
                    }

                };
            }
            return this.cookie;
        }

        public Map getHeader() {
            if (this.header == null) {
                this.header = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeaderNames();
                    }

                    protected Object getAttribute(String name) {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeader(name);
                    }
                };
            }
            return this.header;
        }

        public Map getHeaderValues() {
            if (this.headerValues == null) {
                this.headerValues = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeaderNames();
                    }

                    protected Object getAttribute(String name) {
                        Enumeration e = ((HttpServletRequest) page.getRequest())
                                .getHeaders(name);
                        if (e != null) {
                            List list = new ArrayList();
                            while (e.hasMoreElements()) {
                                list.add(e.nextElement().toString());
                            }
                            return (String[]) list.toArray(new String[list
                                    .size()]);
                        }
                        return null;
                    }

                };
            }
            return this.headerValues;
        }

        public Map getInitParam() {
            if (this.initParam == null) {
                this.initParam = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return page.getServletContext().getInitParameterNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getServletContext().getInitParameter(name);
                    }
                };
            }
            return this.initParam;
        }

        public PageContext getPageContext() {
            return this.page;
        }

        public Map getPageScope() {
            if (this.pageScope == null) {
                this.pageScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        page.setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        page.removeAttribute(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page
                                .getAttributeNamesInScope(PageContext.PAGE_SCOPE);
                    }

                    protected Object getAttribute(String name) {
                        return page.getAttribute(name);
                    }
                };
            }
            return this.pageScope;
        }

        public Map getParam() {
            if (this.param == null) {
                this.param = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getParameterNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getRequest().getParameter(name);
                    }
                };
            }
            return this.param;
        }

        public Map getParamValues() {
            if (this.paramValues == null) {
                this.paramValues = new ScopeMap() {
                    protected Object getAttribute(String name) {
                        return page.getRequest().getParameterValues(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getParameterNames();
                    }
                };
            }
            return this.paramValues;
        }

        public Map getRequestScope() {
            if (this.requestScope == null) {
                this.requestScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        page.getRequest().setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        page.getRequest().removeAttribute(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getAttributeNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getRequest().getAttribute(name);
                    }
                };
            }
            return this.requestScope;
        }

        public Map getSessionScope() {
            if (this.sessionScope == null) {
                this.sessionScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        ((HttpServletRequest) page.getRequest()).getSession()
                                .setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            session.removeAttribute(name);
                        }
                    }

                    protected Enumeration getAttributeNames() {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            return session.getAttributeNames();
                        }
                        return null;
                    }

                    protected Object getAttribute(String name) {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            return session.getAttribute(name);
                        }
                        return null;
                    }
                };
            }
            return this.sessionScope;
        }
    }

    private abstract static class ScopeMap extends AbstractMap {

        protected abstract Enumeration getAttributeNames();

        protected abstract Object getAttribute(String name);

        protected void removeAttribute(String name) {
            throw new UnsupportedOperationException();
        }

        protected void setAttribute(String name, Object value) {
            throw new UnsupportedOperationException();
        }

        public final Set entrySet() {
            Enumeration e = getAttributeNames();
            Set set = new HashSet();
            if (e != null) {
                while (e.hasMoreElements()) {
                    set.add(new ScopeEntry((String) e.nextElement()));
                }
            }
            return set;
        }

        private class ScopeEntry implements Map.Entry {

            private final String key;

            public ScopeEntry(String key) {
                this.key = key;
            }

            public Object getKey() {
                return (Object) this.key;
            }

            public Object getValue() {
                return getAttribute(this.key);
            }

            public Object setValue(Object value) {
                if (value == null) {
                    removeAttribute(this.key);
                } else {
                    setAttribute(this.key, value);
                }
                return null;
            }

            public boolean equals(Object obj) {
                return (obj != null && this.hashCode() == obj.hashCode());
            }

            public int hashCode() {
                return this.key.hashCode();
            }

        }

        public final Object get(Object key) {
            if (key != null) {
                return getAttribute(key.toString());
            }
            return null;
        }

        public final Object put(Object key, Object value) {
            if (key == null) {
                throw new NullPointerException();
            }
            if (value == null) {
                this.removeAttribute(key.toString());
            } else {
                this.setAttribute(key.toString(), value);
            }
            return null;
        }

        public final Object remove(Object key) {
            if (key == null) {
                throw new NullPointerException();
            }
            this.removeAttribute(key.toString());
            return null;
        }

    }

}