pagecontextimpl.java

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/*
 * Copyright 1999,2004 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 org.apache.jasper.runtime;

import java.io.IOException;
import java.io.Writer;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Enumeration;
import java.util.Hashtable;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.VariableResolver;
import javax.servlet.jsp.tagext.BodyContent;

import org.apache.commons.el.ExpressionEvaluatorImpl;
import org.apache.commons.el.VariableResolverImpl;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.jasper.Constants;
import org.apache.jasper.compiler.Localizer;
import org.apache.jasper.security.SecurityUtil;

/**
 * Implementation of the PageContext class from the JSP spec.
 * Also doubles as a VariableResolver for the EL.
 *
 * @author Anil K. Vijendran
 * @author Larry Cable
 * @author Hans Bergsten
 * @author Pierre Delisle
 * @author Mark Roth
 * @author Jan Luehe
 */
public class PageContextImpl extends PageContext implements VariableResolver {

    // Logger
    private static Log log = LogFactory.getLog(PageContextImpl.class);

    // The expression evaluator, for evaluating EL expressions.
    private static ExpressionEvaluatorImpl elExprEval
	= new ExpressionEvaluatorImpl(false);

    // The variable resolver, for evaluating EL expressions.
    private VariableResolverImpl variableResolver;

    private BodyContentImpl[] outs;
    private int depth;

    // per-servlet state
    private Servlet servlet;
    private ServletConfig config;
    private ServletContext context;
    private JspFactory factory;
    private boolean needsSession;
    private String errorPageURL;
    private boolean autoFlush;
    private int	bufferSize;

    // page-scope attributes
    private transient Hashtable	attributes;

    // per-request state
    private transient ServletRequest request;
    private transient ServletResponse response;
    private transient Object page;
    private transient HttpSession session;
    private boolean isIncluded;

    // initial output stream
    private transient JspWriter out;
    private transient JspWriterImpl baseOut;

    /*
     * Constructor.
     */
    PageContextImpl(JspFactory factory) {
        this.factory = factory;
	this.variableResolver = new VariableResolverImpl(this);
	this.outs = new BodyContentImpl[0];
	this.attributes = new Hashtable(16);
	this.depth = -1;
    }

    public void initialize(Servlet servlet,
			   ServletRequest request,
                           ServletResponse response,
			   String errorPageURL,
                           boolean needsSession,
			   int bufferSize,
                           boolean autoFlush) throws IOException {

	_initialize(servlet, request, response, errorPageURL, needsSession,
		    bufferSize, autoFlush);
    }

    private void _initialize(Servlet servlet,
			     ServletRequest request,
			     ServletResponse response,
			     String errorPageURL,
			     boolean needsSession,
			     int bufferSize,
			     boolean autoFlush) throws IOException {

	// initialize state
	this.servlet = servlet;
	this.config = servlet.getServletConfig();
	this.context = config.getServletContext();
	this.needsSession = needsSession;
	this.errorPageURL = errorPageURL;
	this.bufferSize = bufferSize;
	this.autoFlush = autoFlush;
	this.request = request;
 	this.response = response;

	// Setup session (if required)
	if (request instanceof HttpServletRequest && needsSession)
	    this.session = ((HttpServletRequest)request).getSession();
	if (needsSession && session == null)
	    throw new IllegalStateException
                ("Page needs a session and none is available");

        // initialize the initial out ...
        depth = -1;
        if (this.baseOut == null) {
            this.baseOut = new JspWriterImpl(response, bufferSize, autoFlush);
        } else {
            this.baseOut.init(response, bufferSize, autoFlush);
        }
        this.out = baseOut;

	// register names/values as per spec
	setAttribute(OUT, this.out);
	setAttribute(REQUEST, request);
	setAttribute(RESPONSE, response);

	if (session != null)
	    setAttribute(SESSION, session);

	setAttribute(PAGE, servlet);
	setAttribute(CONFIG, config);
	setAttribute(PAGECONTEXT, this);
	setAttribute(APPLICATION, context);

	isIncluded = request.getAttribute(
	    "javax.servlet.include.servlet_path") != null;
    }

    public void release() {
        out = baseOut;
	try {
	    if (isIncluded) {
		((JspWriterImpl)out).flushBuffer();
                // push it into the including jspWriter
	    } else {
                // Old code:
                //out.flush();
                // Do not flush the buffer even if we're not included (i.e.
                // we are the main page. The servlet will flush it and close
                // the stream.
                ((JspWriterImpl)out).flushBuffer();
            }
	} catch (IOException ex) {
	    log.warn("Internal error flushing the buffer in release()");
	}

	servlet = null;
	config = null;
	context = null;
	needsSession = false;
	errorPageURL = null;
	bufferSize = JspWriter.DEFAULT_BUFFER;
	autoFlush = true;
	request = null;
	response = null;
        depth = -1;
	baseOut.recycle();
	session = null;

	attributes.clear();
    }

    public Object getAttribute(final String name) {

        if (name == null) {
            throw new NullPointerException(
                    Localizer.getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()){
            return AccessController.doPrivileged(new PrivilegedAction(){
                public Object run(){
                    return doGetAttribute(name);
                }
            });
        } else {
            return doGetAttribute(name);
        }

    }

    private Object doGetAttribute(String name){
        return attributes.get(name);
    }

    public Object getAttribute(final String name, final int scope) {

        if (name == null) {
            throw new NullPointerException(
                    Localizer.getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()){
            return AccessController.doPrivileged(new PrivilegedAction(){
                public Object run(){
                    return doGetAttribute(name, scope);
                }
            });
        } else {
            return doGetAttribute(name, scope);
        }

    }

    private Object doGetAttribute(String name, int scope){
        switch (scope) {
            case PAGE_SCOPE:
            return attributes.get(name);

            case REQUEST_SCOPE:
            return request.getAttribute(name);

            case SESSION_SCOPE:
            if (session == null) {
                throw new IllegalStateException(
                        Localizer.getMessage("jsp.error.page.noSession"));
            }
            return session.getAttribute(name);

            case APPLICATION_SCOPE:
            return context.getAttribute(name);

            default:
            throw new IllegalArgumentException("Invalid scope");
        }
    }

    public void setAttribute(final String name, final Object attribute) {

        if (name == null) {
            throw new NullPointerException(
                    Localizer.getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()){
            AccessController.doPrivileged(new PrivilegedAction(){
                public Object run(){
                    doSetAttribute(name, attribute);
                    return null;
                }
            });
        } else {
            doSetAttribute(name, attribute);
        }
    }

    private void doSetAttribute(String name, Object attribute){
        if (attribute != null) {
            attributes.put(name, attribute);
        } else {
            removeAttribute(name, PAGE_SCOPE);
        }
    }

    public void setAttribute(final String name, final Object o, final int scope) {

        if (name == null) {
            throw new NullPointerException(
                    Localizer.getMessage("jsp.error.attribute.null_name"));
        }

        if (SecurityUtil.isPackageProtectionEnabled()){
            AccessController.doPrivileged(new PrivilegedAction(){
                public Object run(){
                    doSetAttribute(name, o, scope);