/*
* 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.
*
* $Header:$
*/
package org.apache.beehive.netui.util.internal;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletContext;
import javax.servlet.ServletResponse;
import javax.servlet.ServletRequest;
import javax.servlet.ServletException;
import java.io.PrintStream;
import java.util.Enumeration;
import org.apache.beehive.netui.util.logging.Logger;
public class ServletUtils {
private static final Logger LOG = Logger.getInstance(ServletUtils.class);
public static final String SESSION_MUTEX_ATTRIBUTE = ServletUtils.class.getName() + ".MUTEX";
/**
* Print parameters and attributes in the given request.
*
* @param request the current HttpServletRequest.
* @param output a PrintStream to which to output request parameters and request/session
* attributes; if <code>null</null>, <code>System.err</code> is used.
*
*/
public static void dumpRequest( ServletRequest request, PrintStream output )
{
if ( output == null )
{
output = System.err;
}
output.println( "*** ServletRequest " + request );
if ( request instanceof HttpServletRequest )
{
output.println( " uri = " + ( ( HttpServletRequest ) request ).getRequestURI() );
}
for ( Enumeration e = request.getParameterNames(); e.hasMoreElements(); )
{
String name = ( String ) e.nextElement();
output.println( " parameter " + name + " = " + request.getParameter( name ) );
}
for ( Enumeration e = request.getAttributeNames(); e.hasMoreElements(); )
{
String name = ( String ) e.nextElement();
output.println( " attribute " + name + " = " + request.getAttribute( name ) );
}
if ( request instanceof HttpServletRequest )
{
HttpSession session = ( ( HttpServletRequest ) request ).getSession( false );
if ( session != null )
{
for ( Enumeration e = session.getAttributeNames(); e.hasMoreElements(); )
{
String name = ( String ) e.nextElement();
output.println( " session attribute " + name + " = " + session.getAttribute( name ) );
}
}
}
}
/**
* Print attributes in the given ServletContext.
*
* @param context the current ServletContext.
* @param output a PrintStream to which to output ServletContext attributes; if <code>null</null>,
<code>System.err</code> is used.
*
*/
public static void dumpServletContext( ServletContext context, PrintStream output )
{
if ( output == null )
{
output = System.err;
}
output.println( "*** ServletContext " + context );
for ( Enumeration e = context.getAttributeNames(); e.hasMoreElements(); )
{
String name = ( String ) e.nextElement();
output.println( " attribute " + name + " = " + context.getAttribute( name ) );
}
}
/**
* Set response headers to prevent caching of the response by the browser.
*
* @param response the current ServletResponse
*/
public static void preventCache( ServletResponse response )
{
if ( response instanceof HttpServletResponse )
{
HttpServletResponse httpResponse = ( HttpServletResponse ) response;
httpResponse.setHeader( "Pragma", "No-cache" );
httpResponse.setHeader( "Cache-Control", "no-cache,no-store,max-age=0" );
httpResponse.setDateHeader( "Expires", 1 );
}
}
/**
* Get the base filename of the given URI.
*
* @param uri the URI from which to get the base filename.
* @return a String containing everything after the last slash of the given URI.
*/
public static String getBaseName( String uri )
{
int lastSlash = uri.lastIndexOf( '/' );
assert lastSlash != -1 : uri;
assert lastSlash < uri.length() - 1 : "URI must not end with a slash: " + uri;
return uri.substring( lastSlash + 1 );
}
/**
* Get the directory path of the given URI.
*
* @param uri the URI from which to get the directory path.
* @return a String containing everything before the last slash of the given URI.
*/
public static String getDirName( String uri )
{
int lastSlash = uri.lastIndexOf( '/' );
assert lastSlash != -1 : uri;
assert uri.length() > 1 : uri;
assert lastSlash < uri.length() - 1 : "URI must not end with a slash: " + uri;
return uri.substring( 0, lastSlash );
}
/**
* This initializes the 'cause' on the exception before throwing it; otherwise, the chain of exceptions is hidden
* because of legacy behavior in ServletException ('rootCause' vs. 'cause').
*/
public static void throwServletException(Throwable cause)
throws ServletException
{
ServletException servletException = new ServletException(cause);
// todo: future cleanup
// the servlet 2.5 api sets does the equivalent of initCause in its constructor
// where the servlet 2.4 api does not, so check for the 2.5 behavior before setting initCause
if (servletException.getCause() == null) {
servletException.initCause(cause);
}
throw servletException;
}
/**
* Returns a mutex object for the given {@link HttpSession} that can be used
* as a lock for a given session. For example, to synchronize lazy
* initialization of session scoped objects.
*
* <p>The semantics for locking on an HttpSession object are unspecified, and
* servlet containers are free to implement the HttpSession in such a way
* that acquiring a lock on the HttpSession itself is not safe. When used
* in conjunction with a HttpSessionListener (such as NetUI's
* HttpSessionMutexListener) that puts a mutex object on the session when
* the session is created, this method provides a lock that is 100% safe
* to use across servlet containers. If a HttpSessionListener is not
* registered in web.xml and there is no object for the given attribute name,
* the HttpSession itself is returned as the next best lock.</p>
*
* @param httpSession the current session
* @param attributeName the attribute name of the mutex object on the session
* @return a mutex that can be used to serialize operations on the HttpSession
*/
public static Object getSessionMutex(HttpSession httpSession, String attributeName) {
assert httpSession != null : "HttpSession must not be null";
assert attributeName != null : "The attribute name must not be null";
Object mutex = httpSession.getAttribute(attributeName);
if(mutex == null)
mutex = httpSession;
assert mutex != null;
if(LOG.isDebugEnabled())
LOG.debug("Using session lock of type: " + mutex.getClass());
return mutex;
}
}