org.apache.tapestry5.services.assets.AssetRequestHandler Maven / Gradle / Ivy
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// Copyright 2010 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.tapestry5.services.assets;
import java.io.IOException;
import javax.servlet.http.HttpServletResponse;
import org.apache.tapestry5.Asset;
import org.apache.tapestry5.SymbolConstants;
import org.apache.tapestry5.internal.services.AssetDispatcher;
import org.apache.tapestry5.services.Request;
import org.apache.tapestry5.services.Response;
/**
* Handler for asset requests, which expose some kind of {@link Asset} to
* the user agent (i.e., the client web browser). Starting in Tapestry 5.2,
* asset paths are more structured, consisting of four parts:
*
* /assets/
-- the root path for all assets
* -
* application version -- the application version, as defined by the
* {@link SymbolConstants#APPLICATION_VERSION} symbol
*
- handler id -- a handler for this part of the asset path (defined by contributions to the
*
AssetDispatcher
service)
* - extra path -- additional path beyond the handler id, used to identify the specific resource
*
*
* So, an example path might be /assets/1.0.1/corelib/components/select.png
. The handler id would be
* corelib
, and the extra path would be components/select.png
.
*
* @since 5.2.0
* @see AssetDispatcher
*/
public interface AssetRequestHandler
{
/**
* Given a request targeted (via the handler id) to the specific handler, process the request.
* The handler is responsible for processing the request, sending back either a bytestream
* (via {@link Response#getOutputStream(String)}) or an error response
* (via {@link Response#sendError(int, String)}). It is the handler's responsibility to allow
* for client-side caching (possibly sending an {@link HttpServletResponse#SC_NOT_MODIFIED} response).
*
* The handler should return true if it provided a response. If the handler returns false, this indicates that the
* extra path did not identify a known asset (virtual or otherwise) and the AssetDispatcher service should send a
* {@link HttpServletResponse#SC_NOT_FOUND} response.
*
* @param request
* incoming asset request
* @param response
* used to send a response to client
* @param extraPath
* additional path to identify the specific asset
* @return true if request handler, false if asset not found
*/
boolean handleAssetRequest(Request request, Response response, String extraPath) throws IOException;
}