1/*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package javax.activation;
27
28import java.io.File;
29import java.util.Map;
30import java.util.WeakHashMap;
31
32/**
33 * The FileTypeMap is an abstract class that provides a data typing
34 * interface for files. Implementations of this class will
35 * implement the getContentType methods which will derive a content
36 * type from a file name or a File object. FileTypeMaps could use any
37 * scheme to determine the data type, from examining the file extension
38 * of a file (like the MimetypesFileTypeMap) to opening the file and
39 * trying to derive its type from the contents of the file. The
40 * FileDataSource class uses the default FileTypeMap (a MimetypesFileTypeMap
41 * unless changed) to determine the content type of files.
42 *
43 * @see javax.activation.FileTypeMap
44 * @see javax.activation.FileDataSource
45 * @see javax.activation.MimetypesFileTypeMap
46 *
47 * @since 1.6
48 */
49
50public abstract class FileTypeMap {
51
52    private static FileTypeMap defaultMap = null;
53    private static Map<ClassLoader,FileTypeMap> map =
54                                new WeakHashMap<ClassLoader,FileTypeMap>();
55
56    /**
57     * The default constructor.
58     */
59    public FileTypeMap() {
60        super();
61    }
62
63    /**
64     * Return the type of the file object. This method should
65     * always return a valid MIME type.
66     *
67     * @param file A file to be typed.
68     * @return The content type.
69     */
70    abstract public String getContentType(File file);
71
72    /**
73     * Return the type of the file passed in.  This method should
74     * always return a valid MIME type.
75     *
76     * @param filename the pathname of the file.
77     * @return The content type.
78     */
79    abstract public String getContentType(String filename);
80
81    /**
82     * Sets the default FileTypeMap for the system. This instance
83     * will be returned to callers of getDefaultFileTypeMap.
84     *
85     * @param fileTypeMap The FileTypeMap.
86     * @exception SecurityException if the caller doesn't have permission
87     *                                  to change the default
88     */
89    public static synchronized void setDefaultFileTypeMap(FileTypeMap fileTypeMap) {
90        SecurityManager security = System.getSecurityManager();
91        if (security != null) {
92            try {
93                // if it's ok with the SecurityManager, it's ok with me...
94                security.checkSetFactory();
95            } catch (SecurityException ex) {
96                // otherwise, we also allow it if this code and the
97                // factory come from the same (non-system) class loader (e.g.,
98                // the JAF classes were loaded with the applet classes).
99                ClassLoader cl = FileTypeMap.class.getClassLoader();
100                if (cl == null || cl.getParent() == null ||
101                    cl != fileTypeMap.getClass().getClassLoader())
102                    throw ex;
103            }
104        }
105        // remove any per-thread-context-class-loader FileTypeMap
106        map.remove(SecuritySupport.getContextClassLoader());
107        defaultMap = fileTypeMap;
108    }
109
110    /**
111     * Return the default FileTypeMap for the system.
112     * If setDefaultFileTypeMap was called, return
113     * that instance, otherwise return an instance of
114     * <code>MimetypesFileTypeMap</code>.
115     *
116     * @return The default FileTypeMap
117     * @see javax.activation.FileTypeMap#setDefaultFileTypeMap
118     */
119    public static synchronized FileTypeMap getDefaultFileTypeMap() {
120        if (defaultMap != null)
121            return defaultMap;
122
123        // fetch per-thread-context-class-loader default
124        ClassLoader tccl = SecuritySupport.getContextClassLoader();
125        FileTypeMap def = map.get(tccl);
126        if (def == null) {
127            def = new MimetypesFileTypeMap();
128            map.put(tccl, def);
129        }
130        return def;
131    }
132}
133