Package javax.servlet.jsp.el

Source Code of javax.servlet.jsp.el.ScopedAttributeELResolver

/*
* 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.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.PropertyNotFoundException;
import javax.el.PropertyNotWritableException;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.PageContext;

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

  public ScopedAttributeELResolver() {
    super();
  }

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

    if (base == null) {
      context.setPropertyResolved(true);
      if (property != null) {
        String key = property.toString();
        PageContext page = (PageContext) context
            .getContext(JspContext.class);
        return page.findAttribute(key);
      }
    }

    return null;
  }

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

    if (base == null) {
      context.setPropertyResolved(true);
      return Object.class;
    }

    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) {
      context.setPropertyResolved(true);
      if (property != null) {
        String key = property.toString();
        PageContext page = (PageContext) context
            .getContext(JspContext.class);
        int scope = page.getAttributesScope(key);
        if (scope != 0) {
          page.setAttribute(key, value, scope);
        } else {
          page.setAttribute(key, value);
        }
      }
    }
  }

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

    if (base == null) {
      context.setPropertyResolved(true);
    }

    return false;
  }

  public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {

    PageContext ctxt = (PageContext) context.getContext(JspContext.class);
    List<FeatureDescriptor> list = new ArrayList<FeatureDescriptor>();
    Enumeration e;
    Object value;
    String name;

    e = ctxt.getAttributeNamesInScope(PageContext.PAGE_SCOPE);
    while (e.hasMoreElements()) {
      name = (String) e.nextElement();
      value = ctxt.getAttribute(name, PageContext.PAGE_SCOPE);
      FeatureDescriptor descriptor = new FeatureDescriptor();
      descriptor.setName(name);
      descriptor.setDisplayName(name);
      descriptor.setExpert(false);
      descriptor.setHidden(false);
      descriptor.setPreferred(true);
      descriptor.setShortDescription("page scoped attribute");
      descriptor.setValue("type", value.getClass());
      descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
      list.add(descriptor);
    }

    e = ctxt.getAttributeNamesInScope(PageContext.REQUEST_SCOPE);
    while (e.hasMoreElements()) {
      name = (String) e.nextElement();
      value = ctxt.getAttribute(name, PageContext.REQUEST_SCOPE);
      FeatureDescriptor descriptor = new FeatureDescriptor();
      descriptor.setName(name);
      descriptor.setDisplayName(name);
      descriptor.setExpert(false);
      descriptor.setHidden(false);
      descriptor.setPreferred(true);
      descriptor.setShortDescription("request scope attribute");
      descriptor.setValue("type", value.getClass());
      descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
      list.add(descriptor);
    }

    if (ctxt.getSession() != null) {
      e = ctxt.getAttributeNamesInScope(PageContext.SESSION_SCOPE);
      while (e.hasMoreElements()) {
        name = (String) e.nextElement();
        value = ctxt.getAttribute(name, PageContext.SESSION_SCOPE);
        FeatureDescriptor descriptor = new FeatureDescriptor();
        descriptor.setName(name);
        descriptor.setDisplayName(name);
        descriptor.setExpert(false);
        descriptor.setHidden(false);
        descriptor.setPreferred(true);
        descriptor.setShortDescription("session scoped attribute");
        descriptor.setValue("type", value.getClass());
        descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
        list.add(descriptor);
      }
    }

    e = ctxt.getAttributeNamesInScope(PageContext.APPLICATION_SCOPE);
    while (e.hasMoreElements()) {
      name = (String) e.nextElement();
      value = ctxt.getAttribute(name, PageContext.APPLICATION_SCOPE);
      FeatureDescriptor descriptor = new FeatureDescriptor();
      descriptor.setName(name);
      descriptor.setDisplayName(name);
      descriptor.setExpert(false);
      descriptor.setHidden(false);
      descriptor.setPreferred(true);
      descriptor.setShortDescription("application scoped attribute");
      descriptor.setValue("type", value.getClass());
      descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
      list.add(descriptor);
    }
    return list.iterator();
  }

  private static void appendEnumeration(Collection c, Enumeration e) {
    while (e.hasMoreElements()) {
      c.add(e.nextElement());
    }
  }

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