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1   package org.apache.turbine.services.template;
2   
3   
4   /*
5    * Licensed to the Apache Software Foundation (ASF) under one
6    * or more contributor license agreements.  See the NOTICE file
7    * distributed with this work for additional information
8    * regarding copyright ownership.  The ASF licenses this file
9    * to you under the Apache License, Version 2.0 (the
10   * "License"); you may not use this file except in compliance
11   * with the License.  You may obtain a copy of the License at
12   *
13   *   http://www.apache.org/licenses/LICENSE-2.0
14   *
15   * Unless required by applicable law or agreed to in writing,
16   * software distributed under the License is distributed on an
17   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
18   * KIND, either express or implied.  See the License for the
19   * specific language governing permissions and limitations
20   * under the License.
21   */
22  
23  
24  import java.util.Hashtable;
25  
26  /**
27   * This is the interface that all template engine services must adhere
28   * to. This includes the Velocity, WebMacro, FreeMarker, and JSP
29   * services.
30   *
31   * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
32   * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
33   * @version $Id: TemplateEngineService.java 1078552 2011-03-06 19:58:46Z tv $ */
34  public interface TemplateEngineService
35  {
36      static final String TEMPLATE_EXTENSIONS = "template.extension";
37      static final String DEFAULT_TEMPLATE_EXTENSION = "template.default.extension";
38      static final String DEFAULT_PAGE = "default.page";
39      static final String DEFAULT_SCREEN = "default.screen";
40      static final String DEFAULT_LAYOUT = "default.layout";
41      static final String DEFAULT_NAVIGATION = "default.navigation";
42      static final String DEFAULT_ERROR_SCREEN = "default.error.screen";
43      static final String DEFAULT_LAYOUT_TEMPLATE = "default.layout.template";
44      static final String DEFAULT_SCREEN_TEMPLATE = "default.screen.template";
45      static final String DEFAULT_NAVIGATION_TEMPLATE = "default.navigation.template";
46  
47      /**
48       * Return the configuration of the template engine in
49       * the form of a Hashtable.
50       */
51      Hashtable<String, Object> getTemplateEngineServiceConfiguration();
52  
53      /**
54       * Initializes file extension associations and registers with the
55       * template service.
56       *
57       * @param defaultExt The default file extension association to use
58       *                   in case of properties file misconfiguration.
59       */
60      void registerConfiguration(String defaultExt);
61  
62      /**
63       * Supplies the file extension to key this engine in {@link
64       * org.apache.turbine.services.template.TemplateService}'s
65       * registry with.
66       */
67      String[] getAssociatedFileExtensions();
68  
69      /**
70       * Use the specific template engine to determine whether
71       * a given template exists. This allows Turbine the TemplateService
72       * to delegate the search for a template to the template
73       * engine being used for the view. This gives us the
74       * advantage of fully utilizing the capabilities of
75       * template engine with respect to retrieving templates
76       * from arbitrary sources.
77       *
78       * @param template The name of the template to check the existance of.
79       * @return         Whether the specified template exists.
80       */
81      boolean templateExists(String template);
82  }