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| 1 | /* | ||
| 2 | * Copyright (c) 2008, 2011, 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 | |||
| 26 | package sun.nio.fs; | ||
| 27 | |||
| 28 | import java.nio.file.Path; | ||
| 29 | import java.nio.file.spi.FileTypeDetector; | ||
| 30 | import java.util.Locale; | ||
| 31 | import java.io.IOException; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * Base implementation of FileTypeDetector | ||
| 35 | */ | ||
| 36 | |||
| 37 | public abstract class AbstractFileTypeDetector | ||
| 38 | extends FileTypeDetector | ||
| 39 | { | ||
| 40 | protected AbstractFileTypeDetector() { | ||
| 41 | super(); | ||
| 42 | } | ||
| 43 | |||
| 44 | /** | ||
| 45 | * Invokes the appropriate probe method to guess a file's content type, | ||
| 46 | * and checks that the content type's syntax is valid. | ||
| 47 | */ | ||
| 48 | @Override | ||
| 49 | public final String probeContentType(Path file) throws IOException { | ||
| 50 | if (file == null) | ||
| 51 | throw new NullPointerException("'file' is null"); | ||
| 52 | String result = implProbeContentType(file); | ||
| 53 | return (result == null) ? null : parse(result); | ||
| 54 | } | ||
| 55 | |||
| 56 | /** | ||
| 57 | * Probes the given file to guess its content type. | ||
| 58 | */ | ||
| 59 | protected abstract String implProbeContentType(Path file) | ||
| 60 | throws IOException; | ||
| 61 | |||
| 62 | /** | ||
| 63 | * Parses a candidate content type into its type and subtype, returning | ||
| 64 | * null if either token is invalid. | ||
| 65 | */ | ||
| 66 | private static String parse(String s) { | ||
| 67 | int slash = s.indexOf('/'); | ||
| 68 | int semicolon = s.indexOf(';'); | ||
| 69 | if (slash < 0) | ||
| 70 | return null; // no subtype | ||
| 71 | String type = s.substring(0, slash).trim().toLowerCase(Locale.ENGLISH); | ||
| 72 | if (!isValidToken(type)) | ||
| 73 | return null; // invalid type | ||
| 74 | String subtype = (semicolon < 0) ? s.substring(slash + 1) : | ||
| 75 | s.substring(slash + 1, semicolon); | ||
| 76 | subtype = subtype.trim().toLowerCase(Locale.ENGLISH); | ||
| 77 | if (!isValidToken(subtype)) | ||
| 78 | return null; // invalid subtype | ||
| 79 | StringBuilder sb = new StringBuilder(type.length() + subtype.length() + 1); | ||
| 80 | sb.append(type); | ||
| 81 | sb.append('/'); | ||
| 82 | sb.append(subtype); | ||
| 83 | return sb.toString(); | ||
| 84 | } | ||
| 85 | |||
| 86 | /** | ||
| 87 | * Special characters | ||
| 88 | */ | ||
| 89 | private static final String TSPECIALS = "()<>@,;:/[]?=\\\""; | ||
| 90 | |||
| 91 | /** | ||
| 92 | * Returns true if the character is a valid token character. | ||
| 93 | */ | ||
| 94 | private static boolean isTokenChar(char c) { | ||
| 95 | return (c > 040) && (c < 0177) && (TSPECIALS.indexOf(c) < 0); | ||
| 96 | } | ||
| 97 | |||
| 98 | /** | ||
| 99 | * Returns true if the given string is a legal type or subtype. | ||
| 100 | */ | ||
| 101 | private static boolean isValidToken(String s) { | ||
| 102 | int len = s.length(); | ||
| 103 | if (len == 0) | ||
| 104 | return false; | ||
| 105 | for (int i = 0; i < len; i++) { | ||
| 106 | if (!isTokenChar(s.charAt(i))) | ||
| 107 | return false; | ||
| 108 | } | ||
| 109 | return true; | ||
| 110 | } | ||
| 111 | } | ||