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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.webkit;
     18 
     19 import android.text.TextUtils;
     20 import java.util.regex.Pattern;
     21 import libcore.net.MimeUtils;
     22 
     23 /**
     24  * Two-way map that maps MIME-types to file extensions and vice versa.
     25  *
     26  * <p>See also {@link java.net.URLConnection#guessContentTypeFromName}
     27  * and {@link java.net.URLConnection#guessContentTypeFromStream}. This
     28  * class and {@code URLConnection} share the same MIME-type database.
     29  */
     30 public class MimeTypeMap {
     31     private static final MimeTypeMap sMimeTypeMap = new MimeTypeMap();
     32 
     33     private MimeTypeMap() {
     34     }
     35 
     36     /**
     37      * Returns the file extension or an empty string iff there is no
     38      * extension. This method is a convenience method for obtaining the
     39      * extension of a url and has undefined results for other Strings.
     40      * @param url
     41      * @return The file extension of the given url.
     42      */
     43     public static String getFileExtensionFromUrl(String url) {
     44         if (!TextUtils.isEmpty(url)) {
     45             int fragment = url.lastIndexOf('#');
     46             if (fragment > 0) {
     47                 url = url.substring(0, fragment);
     48             }
     49 
     50             int query = url.lastIndexOf('?');
     51             if (query > 0) {
     52                 url = url.substring(0, query);
     53             }
     54 
     55             int filenamePos = url.lastIndexOf('/');
     56             String filename =
     57                 0 <= filenamePos ? url.substring(filenamePos + 1) : url;
     58 
     59             // if the filename contains special characters, we don't
     60             // consider it valid for our matching purposes:
     61             if (!filename.isEmpty() &&
     62                 Pattern.matches("[a-zA-Z_0-9\\.\\-\\(\\)\\%]+", filename)) {
     63                 int dotPos = filename.lastIndexOf('.');
     64                 if (0 <= dotPos) {
     65                     return filename.substring(dotPos + 1);
     66                 }
     67             }
     68         }
     69 
     70         return "";
     71     }
     72 
     73     /**
     74      * Return true if the given MIME type has an entry in the map.
     75      * @param mimeType A MIME type (i.e. text/plain)
     76      * @return True iff there is a mimeType entry in the map.
     77      */
     78     public boolean hasMimeType(String mimeType) {
     79         return MimeUtils.hasMimeType(mimeType);
     80     }
     81 
     82     /**
     83      * Return the MIME type for the given extension.
     84      * @param extension A file extension without the leading '.'
     85      * @return The MIME type for the given extension or null iff there is none.
     86      */
     87     public String getMimeTypeFromExtension(String extension) {
     88         return MimeUtils.guessMimeTypeFromExtension(extension);
     89     }
     90 
     91     // Static method called by jni.
     92     private static String mimeTypeFromExtension(String extension) {
     93         return MimeUtils.guessMimeTypeFromExtension(extension);
     94     }
     95 
     96     /**
     97      * Return true if the given extension has a registered MIME type.
     98      * @param extension A file extension without the leading '.'
     99      * @return True iff there is an extension entry in the map.
    100      */
    101     public boolean hasExtension(String extension) {
    102         return MimeUtils.hasExtension(extension);
    103     }
    104 
    105     /**
    106      * Return the registered extension for the given MIME type. Note that some
    107      * MIME types map to multiple extensions. This call will return the most
    108      * common extension for the given MIME type.
    109      * @param mimeType A MIME type (i.e. text/plain)
    110      * @return The extension for the given MIME type or null iff there is none.
    111      */
    112     public String getExtensionFromMimeType(String mimeType) {
    113         return MimeUtils.guessExtensionFromMimeType(mimeType);
    114     }
    115 
    116     /**
    117      * If the given MIME type is null, or one of the "generic" types (text/plain
    118      * or application/octet-stream) map it to a type that Android can deal with.
    119      * If the given type is not generic, return it unchanged.
    120      *
    121      * @param mimeType MIME type provided by the server.
    122      * @param url URL of the data being loaded.
    123      * @param contentDisposition Content-disposition header given by the server.
    124      * @return The MIME type that should be used for this data.
    125      */
    126     /* package */ String remapGenericMimeType(String mimeType, String url,
    127             String contentDisposition) {
    128         // If we have one of "generic" MIME types, try to deduce
    129         // the right MIME type from the file extension (if any):
    130         if ("text/plain".equals(mimeType) ||
    131                 "application/octet-stream".equals(mimeType)) {
    132 
    133             // for attachment, use the filename in the Content-Disposition
    134             // to guess the mimetype
    135             String filename = null;
    136             if (contentDisposition != null) {
    137                 filename = URLUtil.parseContentDisposition(contentDisposition);
    138             }
    139             if (filename != null) {
    140                 url = filename;
    141             }
    142             String extension = getFileExtensionFromUrl(url);
    143             String newMimeType = getMimeTypeFromExtension(extension);
    144             if (newMimeType != null) {
    145                 mimeType = newMimeType;
    146             }
    147         } else if ("text/vnd.wap.wml".equals(mimeType)) {
    148             // As we don't support wml, render it as plain text
    149             mimeType = "text/plain";
    150         } else {
    151             // It seems that xhtml+xml and vnd.wap.xhtml+xml mime
    152             // subtypes are used interchangeably. So treat them the same.
    153             if ("application/vnd.wap.xhtml+xml".equals(mimeType)) {
    154                 mimeType = "application/xhtml+xml";
    155             }
    156         }
    157         return mimeType;
    158     }
    159 
    160     /**
    161      * Get the singleton instance of MimeTypeMap.
    162      * @return The singleton instance of the MIME-type map.
    163      */
    164     public static MimeTypeMap getSingleton() {
    165         return sMimeTypeMap;
    166     }
    167 }
    168