Java tutorial
/* * Copyright (C) 2006 The Android Open Source Project * * 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 android.webkit; import android.annotation.Nullable; import android.annotation.UnsupportedAppUsage; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.Map; /** * Manages the HTTP cache used by an application's {@link WebView} instances. * @deprecated Access to the HTTP cache will be removed in a future release. * @hide Since {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1} */ // The class CacheManager provides the persistent cache of content that is // received over the network. The component handles parsing of HTTP headers and // utilizes the relevant cache headers to determine if the content should be // stored and if so, how long it is valid for. Network requests are provided to // this component and if they can not be resolved by the cache, the HTTP headers // are attached, as appropriate, to the request for revalidation of content. The // class also manages the cache size. // // CacheManager may only be used if your activity contains a WebView. @Deprecated public final class CacheManager { /** * Represents a resource stored in the HTTP cache. Instances of this class * can be obtained by calling * {@link CacheManager#getCacheFile CacheManager.getCacheFile(String, Map<String, String>))}. * * @deprecated Access to the HTTP cache will be removed in a future release. */ @Deprecated public static class CacheResult { // these fields are saved to the database @UnsupportedAppUsage int httpStatusCode; @UnsupportedAppUsage long contentLength; @UnsupportedAppUsage long expires; @UnsupportedAppUsage String expiresString; @UnsupportedAppUsage String localPath; @UnsupportedAppUsage String lastModified; @UnsupportedAppUsage String etag; @UnsupportedAppUsage String mimeType; @UnsupportedAppUsage String location; @UnsupportedAppUsage String encoding; @UnsupportedAppUsage String contentdisposition; @UnsupportedAppUsage String crossDomain; // these fields are NOT saved to the database @UnsupportedAppUsage InputStream inStream; @UnsupportedAppUsage OutputStream outStream; @UnsupportedAppUsage File outFile; /** * Gets the status code of this cache entry. * * @return the status code of this cache entry */ @UnsupportedAppUsage public int getHttpStatusCode() { return httpStatusCode; } /** * Gets the content length of this cache entry. * * @return the content length of this cache entry */ @UnsupportedAppUsage public long getContentLength() { return contentLength; } /** * Gets the path of the file used to store the content of this cache * entry, relative to the base directory of the cache. See * {@link CacheManager#getCacheFileBaseDir CacheManager.getCacheFileBaseDir()}. * * @return the path of the file used to store this cache entry */ @UnsupportedAppUsage public String getLocalPath() { return localPath; } /** * Gets the expiry date of this cache entry, expressed in milliseconds * since midnight, January 1, 1970 UTC. * * @return the expiry date of this cache entry */ @UnsupportedAppUsage public long getExpires() { return expires; } /** * Gets the expiry date of this cache entry, expressed as a string. * * @return the expiry date of this cache entry * */ @UnsupportedAppUsage public String getExpiresString() { return expiresString; } /** * Gets the date at which this cache entry was last modified, expressed * as a string. * * @return the date at which this cache entry was last modified */ @UnsupportedAppUsage public String getLastModified() { return lastModified; } /** * Gets the entity tag of this cache entry. * * @return the entity tag of this cache entry */ @UnsupportedAppUsage public String getETag() { return etag; } /** * Gets the MIME type of this cache entry. * * @return the MIME type of this cache entry */ @UnsupportedAppUsage public String getMimeType() { return mimeType; } /** * Gets the value of the HTTP 'Location' header with which this cache * entry was received. * * @return the HTTP 'Location' header for this cache entry */ @UnsupportedAppUsage public String getLocation() { return location; } /** * Gets the encoding of this cache entry. * * @return the encoding of this cache entry */ @UnsupportedAppUsage public String getEncoding() { return encoding; } /** * Gets the value of the HTTP 'Content-Disposition' header with which * this cache entry was received. * * @return the HTTP 'Content-Disposition' header for this cache entry * */ @UnsupportedAppUsage public String getContentDisposition() { return contentdisposition; } /** * Gets the input stream to the content of this cache entry, to allow * content to be read. See * {@link CacheManager#getCacheFile CacheManager.getCacheFile(String, Map<String, String>)}. * * @return an input stream to the content of this cache entry */ @UnsupportedAppUsage public InputStream getInputStream() { return inStream; } /** * Gets an output stream to the content of this cache entry, to allow * content to be written. See * {@link CacheManager#saveCacheFile CacheManager.saveCacheFile(String, CacheResult)}. * * @return an output stream to the content of this cache entry */ // Note that this is always null for objects returned by getCacheFile()! @UnsupportedAppUsage public OutputStream getOutputStream() { return outStream; } /** * Sets an input stream to the content of this cache entry. * * @param stream an input stream to the content of this cache entry */ @UnsupportedAppUsage public void setInputStream(InputStream stream) { this.inStream = stream; } /** * Sets the encoding of this cache entry. * * @param encoding the encoding of this cache entry */ @UnsupportedAppUsage public void setEncoding(String encoding) { this.encoding = encoding; } /** * @hide */ public void setContentLength(long contentLength) { this.contentLength = contentLength; } } /** * Gets the base directory in which the files used to store the contents of * cache entries are placed. See * {@link CacheManager.CacheResult#getLocalPath CacheManager.CacheResult.getLocalPath()}. * * @return the base directory of the cache * @deprecated This method no longer has any effect and always returns {@code null}. */ @Deprecated @Nullable @UnsupportedAppUsage public static File getCacheFileBaseDir() { return null; } /** * Gets whether the HTTP cache is disabled. * * @return {@code true} if the HTTP cache is disabled * @deprecated This method no longer has any effect and always returns {@code false}. */ @Deprecated @UnsupportedAppUsage public static boolean cacheDisabled() { return false; } /** * Starts a cache transaction. Returns {@code true} if this is the only running * transaction. Otherwise, this transaction is nested inside currently * running transactions and {@code false} is returned. * * @return {@code true} if this is the only running transaction * @deprecated This method no longer has any effect and always returns {@code false}. */ @Deprecated @UnsupportedAppUsage public static boolean startCacheTransaction() { return false; } /** * Ends the innermost cache transaction and returns whether this was the * only running transaction. * * @return {@code true} if this was the only running transaction * @deprecated This method no longer has any effect and always returns {@code false}. */ @Deprecated @UnsupportedAppUsage public static boolean endCacheTransaction() { return false; } /** * Gets the cache entry for the specified URL, or {@code null} if none is found. * If a non-null value is provided for the HTTP headers map, and the cache * entry needs validation, appropriate headers will be added to the map. * The input stream of the CacheEntry object should be closed by the caller * when access to the underlying file is no longer required. * * @param url the URL for which a cache entry is requested * @param headers a map from HTTP header name to value, to be populated * for the returned cache entry * @return the cache entry for the specified URL * @deprecated This method no longer has any effect and always returns {@code null}. */ @Deprecated @Nullable @UnsupportedAppUsage public static CacheResult getCacheFile(String url, Map<String, String> headers) { return null; } /** * Adds a cache entry to the HTTP cache for the specicifed URL. Also closes * the cache entry's output stream. * * @param url the URL for which the cache entry should be added * @param cacheResult the cache entry to add * @deprecated Access to the HTTP cache will be removed in a future release. */ @Deprecated @UnsupportedAppUsage public static void saveCacheFile(String url, CacheResult cacheResult) { saveCacheFile(url, 0, cacheResult); } @UnsupportedAppUsage static void saveCacheFile(String url, long postIdentifier, CacheResult cacheRet) { try { cacheRet.outStream.close(); } catch (IOException e) { return; } // This method is exposed in the public API but the API provides no // way to obtain a new CacheResult object with a non-null output // stream ... // - CacheResult objects returned by getCacheFile() have a null // output stream. // - new CacheResult objects have a null output stream and no // setter is provided. // Since this method throws a null pointer exception in this case, // it is effectively useless from the point of view of the public // API. // // With the Chromium HTTP stack we continue to throw the same // exception for 'backwards compatibility' with the Android HTTP // stack. // // This method is not used from within this package, and for public API // use, we should already have thrown an exception above. assert false; } }