001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry.engine.encoders;
016
017import org.apache.tapestry.INamespace;
018import org.apache.tapestry.engine.ServiceEncoder;
019import org.apache.tapestry.engine.ServiceEncoding;
020import org.apache.tapestry.services.ServiceConstants;
021
022/**
023 * The canonical implementation of {@link org.apache.tapestry.engine.ServiceEncoder}, it encodes
024 * page name and a service name. The page name becomes the servlet path, prefixed with "/" and
025 * suffixed with a dot and a particular extension. In this way, "/app?service=page&page=Home"
026 * becomes simply "Home.html". This is most suitable for the "page" and "external" services.
027 * 
028 * @author Howard M. Lewis Ship
029 * @since 4.0
030 */
031public class PageServiceEncoder implements ServiceEncoder
032{
033    private String _extension;
034
035    private String _serviceName;
036
037    public void encode(ServiceEncoding encoding)
038    {
039        String service = encoding.getParameterValue(ServiceConstants.SERVICE);
040
041        if (!service.equals(_serviceName))
042            return;
043
044        String pageName = encoding.getParameterValue(ServiceConstants.PAGE);
045
046        // Only handle pages in the application namespace (not from a library).
047
048        if (pageName.indexOf(INamespace.SEPARATOR) >= 0)
049            return;
050
051        StringBuffer buffer = new StringBuffer("/");
052        buffer.append(pageName);
053        buffer.append('.');
054        buffer.append(_extension);
055
056        encoding.setServletPath(buffer.toString());
057
058        encoding.setParameterValue(ServiceConstants.SERVICE, null);
059        encoding.setParameterValue(ServiceConstants.PAGE, null);
060    }
061
062    public void decode(ServiceEncoding encoding)
063    {
064        String servletPath = encoding.getServletPath();
065
066        int dotx = servletPath.lastIndexOf('.');
067        if (dotx < 0)
068            return;
069
070        String extension = servletPath.substring(dotx + 1);
071
072        if (!extension.equals(_extension))
073            return;
074
075        // Skip the slash and the dot.
076
077        String page = servletPath.substring(1, dotx);
078
079        encoding.setParameterValue(ServiceConstants.SERVICE, _serviceName);
080        encoding.setParameterValue(ServiceConstants.PAGE, page);
081    }
082
083    public void setExtension(String extension)
084    {
085        _extension = extension;
086    }
087
088    public void setServiceName(String serviceName)
089    {
090        _serviceName = serviceName;
091    }
092}