Java tutorial
/* * Copyright 2008 Google Inc. * * 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 com.google.gwt.resources.ext; import com.google.gwt.core.ext.GeneratorContext; import com.google.gwt.core.ext.UnableToCompleteException; import com.google.gwt.core.ext.typeinfo.JClassType; import java.net.URL; /** * Context object for ResourceGenerators. An instance of this type will be * provided by the resource generation framework to implementations of * ResourceGenerator via {@link ResourceGenerator#init}. Because this interface * is not intended to be implemented by end-users, the API provided by this * interface may be extended in the future. * <p> * Depending on the optimizations made by the implementation of {@link #deploy}, * the resulting URL may or may not be compatible with standard * {@link com.google.gwt.http.client.RequestBuilder} / XMLHttpRequest security * semantics. If the resource is intended to be used with XHR, or if there are * other reasons why embedding the resource is undesirable such as known * incompatibilities, the <code>forceExternal</code> parameter should be set to * <code>true</code> when invoking {@link #deploy}. * </p> */ public interface ResourceContext { /** * Cause a specific collection of bytes to be available in the program's * compiled output. The return value of this method is a Java expression which * will evaluate to the location of the resource at runtime. The exact format * should not be depended upon. * * @param suggestedFileName an unobfuscated filename to possibly use for the * resource * @param mimeType the MIME type of the data being provided * @param data the bytes to add to the output * @param forceExternal prevents embedding of the resource, e.g. in case of * known incompatibilities or for example to enforce compatibility * with security restrictions if the resource is intended to be * accessed via an XMLHttpRequest * @return a Java expression which will evaluate to the location of the * provided resource at runtime */ String deploy(String suggestedFileName, String mimeType, byte[] data, boolean forceExternal) throws UnableToCompleteException; /** * Cause a specific collection of bytes to be available in the program's * compiled output. The return value of this method is a Java expression which * will evaluate to the location of the resource at runtime. The exact format * should not be depended upon. * * @param resource the resource to add to the compiled output * @param forceExternal prevents embedding of the resource, e.g. in case of * known incompatibilities or for example to enforce compatibility * with security restrictions if the resource is intended to be * accessed via an XMLHttpRequest * @return a Java expression which will evaluate to the location of the * provided resource at runtime * @deprecated use {@link #deploy(URL, String, boolean)} instead */ @Deprecated String deploy(URL resource, boolean forceExternal) throws UnableToCompleteException; /** * Cause a specific collection of bytes to be available in the program's * compiled output. The return value of this method is a Java expression which * will evaluate to the location of the resource at runtime. The exact format * should not be depended upon. * * @param resource the resource to add to the compiled output * @param mimeType optional MIME Type to be used for an embedded resource * @param forceExternal prevents embedding of the resource, e.g. in case of * known incompatibilities or for example to enforce compatibility * with security restrictions if the resource is intended to be * accessed via an XMLHttpRequest * @return a Java expression which will evaluate to the location of the * provided resource at runtime */ String deploy(URL resource, String mimeType, boolean forceExternal) throws UnableToCompleteException; /** * Retrieve data from the ResourceContext. * * @param <T> the type of data to retrieve * @param key the key value passed to {@link #getCachedData} * @param clazz the type to which the cached value must be assignable * @return the value previously passed to {@link #putCachedData} or * <code>null</code> if the data was not found * @throws ClassCastException if the cached data is not assignable to the * specified type */ <T> T getCachedData(String key, Class<T> clazz); /** * Return the interface type of the resource bundle being generated. */ JClassType getClientBundleType(); /** * Return the GeneratorContext in which the overall resource generation * framework is being run. Implementations of ResourceGenerator should prefer * {@link #deploy} over {@link GeneratorContext#tryCreateResource} in order to * take advantage of serving optimizations that can be performed by the bundle * architecture. */ GeneratorContext getGeneratorContext(); /** * Returns the simple source name of the implementation of the bundle being * generated. This can be used during code-generation to refer to the instance * of the bundle (e.g. via <code>SimpleSourceName.this</code>). * * @throws IllegalStateException if this method is called during * {@link ResourceGenerator#init} or * {@link ResourceGenerator#prepare} methods. */ String getImplementationSimpleSourceName() throws IllegalStateException; /** * Returns a {@link ClientBundleRequirements} object, which can be used to * track deferred-binding and configuration properties that are relevant to a * resource context. */ ClientBundleRequirements getRequirements(); /** * Store data in the ResourceContext. ResourceGenerators may reduce the amount * of recomputation performed by caching data the ResourceContext. This cache * will be invalidated when the compiler's TypeOracle is refreshed or * replaced. Each ResourceGenerator has an isolated view of the cache. * * @param <T> the type of data being stored * @param key a string key to locate the data * @param value the value to store * @return <code>true</code> if the cache did not previously contain the * key-value pair */ <T> boolean putCachedData(String key, T value); /** * Indicates if the runtime context supports data: urls. When data URLs are * supported by the context, aggregation of resource data into larger payloads * is discouraged, as it offers reduced benefit to the application at runtime. */ boolean supportsDataUrls(); }