| // Copyright 2006, 2008, 2009, 2013 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; |
| |
| import org.apache.tapestry5.ioc.Resource; |
| |
| /** |
| * An Asset is any kind of resource that can be exposed to the client web browser. Although quite often an Asset is a |
| * resource in a web application's context folder, within Tapestry, Assets may also be resources on the classpath (i.e., |
| * packaged inside JARs). |
| * <p/> |
| * An Asset's toString() will return the URL for the resource (the same value as {@link #toClientURL()}). |
| * <p/> |
| * Release 5.1.0.0 introduced {@link org.apache.tapestry5.Asset2}, which extends this interface with an additional |
| * method. |
| * |
| * @see org.apache.tapestry5.services.AssetPathConverter |
| */ |
| public interface Asset |
| { |
| /** |
| * Returns a URL that can be passed, unchanged, to the client in order for it to access the resource. The same value |
| * is returned from <code>toString()</code>. |
| * <p/> |
| * Tapestry's built-in asset types (context and classpath) always incorporate a checksum as part of the path, |
| * and alternate implementations are encouraged to do so as well. In addition, Tapestry ensures that context and |
| * classpath assets have a far-future expires header (to ensure aggressive caching by the client). |
| * <p/>Note that starting in Tapestry 5.4, it is expected that Asset instances recognize |
| * when the underlying Resource's content has changed, and update the clientURL to reflect the new content's |
| * checksum. This wasn't an issue in earlier releases where the clientURL incorporated a version number. |
| * <p/> |
| * Finally, starting in 5.4, this value will often be <em>variant</em>: the exact URL returned will depend on |
| * whether the underlying resource content is compressable, whether the current {@link org.apache.tapestry5.services.Request} |
| * supports compression. |
| * |
| * @see org.apache.tapestry5.services.AssetSource |
| * @see org.apache.tapestry5.services.AssetPathConverter |
| */ |
| String toClientURL(); |
| |
| /** |
| * Returns the underlying Resource for the Asset. |
| */ |
| Resource getResource(); |
| |
| } |