Source Home >> Java Source 1.6.0 >> java.io. V 0.09

001/*
002 * @(#)FileSystem.java	1.18 05/12/01
003 *
004 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
005 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
006 */
007
008package java.io;
009
010
011/**
012 * Package-private abstract class for the local filesystem abstraction.
013 */
014
015abstract class FileSystem {
016
017    /**
018     * Return the FileSystem object representing this platform's local
019     * filesystem.
020     */
021    public static native FileSystem getFileSystem();
022
023
024    /* -- Normalization and construction -- */
025
026    /**
027     * Return the local filesystem's name-separator character.
028     */
029    public abstract char getSeparator();
030
031    /**
032     * Return the local filesystem's path-separator character.
033     */
034    public abstract char getPathSeparator();
035
036    /**
037     * Convert the given pathname string to normal form.  If the string is
038     * already in normal form then it is simply returned.
039     */
040    public abstract String normalize(String path);
041
042    /**
043     * Compute the length of this pathname string's prefix.  The pathname
044     * string must be in normal form.
045     */
046    public abstract int prefixLength(String path);
047
048    /**
049     * Resolve the child pathname string against the parent.
050     * Both strings must be in normal form, and the result
051     * will be in normal form.
052     */
053    public abstract String resolve(String parent, String child);
054
055    /**
056     * Return the parent pathname string to be used when the parent-directory
057     * argument in one of the two-argument File constructors is the empty
058     * pathname.
059     */
060    public abstract String getDefaultParent();
061
062    /**
063     * Post-process the given URI path string if necessary.  This is used on
064     * win32, e.g., to transform "/c:/foo" into "c:/foo".  The path string
065     * still has slash separators; code in the File class will translate them
066     * after this method returns.
067     */
068    public abstract String fromURIPath(String path);
069
070
071    /* -- Path operations -- */
072
073    /**
074     * Tell whether or not the given abstract pathname is absolute.
075     */
076    public abstract boolean isAbsolute(File f);
077
078    /**
079     * Resolve the given abstract pathname into absolute form.  Invoked by the
080     * getAbsolutePath and getCanonicalPath methods in the File class.
081     */
082    public abstract String resolve(File f);
083
084    public abstract String canonicalize(String path) throws IOException;
085
086
087    /* -- Attribute accessors -- */
088
089    /* Constants for simple boolean attributes */
090    public static final int BA_EXISTS    = 0x01;
091    public static final int BA_REGULAR   = 0x02;
092    public static final int BA_DIRECTORY = 0x04;
093    public static final int BA_HIDDEN    = 0x08;
094
095    /**
096     * Return the simple boolean attributes for the file or directory denoted
097     * by the given abstract pathname, or zero if it does not exist or some
098     * other I/O error occurs.
099     */
100    public abstract int getBooleanAttributes(File f);
101
102    public static final int ACCESS_READ    = 0x04;
103    public static final int ACCESS_WRITE   = 0x02;
104    public static final int ACCESS_EXECUTE = 0x01;
105
106    /**
107     * Check whether the file or directory denoted by the given abstract
108     * pathname may be accessed by this process.  The second argument specifies
109     * which access, ACCESS_READ, ACCESS_WRITE or ACCESS_EXECUTE, to check.
110     * Return false if access is denied or an I/O error occurs
111     */
112    public abstract boolean checkAccess(File f, int access);
113    /**
114     * Set on or off the access permission (to owner only or to all) to the file 
115     * or directory denoted by the given abstract pathname, based on the parameters
116     * enable, access and oweronly.
117     */
118    public abstract boolean setPermission(File f, int access, boolean enable, boolean owneronly);
119
120    /**
121     * Return the time at which the file or directory denoted by the given
122     * abstract pathname was last modified, or zero if it does not exist or
123     * some other I/O error occurs.
124     */
125    public abstract long getLastModifiedTime(File f);
126
127    /**
128     * Return the length in bytes of the file denoted by the given abstract
129     * pathname, or zero if it does not exist, is a directory, or some other
130     * I/O error occurs.
131     */
132    public abstract long getLength(File f);
133
134
135    /* -- File operations -- */
136
137    /**
138     * Create a new empty file with the given pathname.  Return
139     * <code>true</code> if the file was created and <code>false</code> if a
140     * file or directory with the given pathname already exists.  Throw an
141     * IOException if an I/O error occurs.
142     */
143    public abstract boolean createFileExclusively(String pathname)
144	throws IOException;
145
146    /**
147     * Delete the file or directory denoted by the given abstract pathname,
148     * returning <code>true</code> if and only if the operation succeeds.
149     */
150    public abstract boolean delete(File f);
151
152    /**
153     * List the elements of the directory denoted by the given abstract
154     * pathname.  Return an array of strings naming the elements of the
155     * directory if successful; otherwise, return <code>null</code>.
156     */
157    public abstract String[] list(File f);
158
159    /**
160     * Create a new directory denoted by the given abstract pathname,
161     * returning <code>true</code> if and only if the operation succeeds.
162     */
163    public abstract boolean createDirectory(File f);
164
165    /**
166     * Rename the file or directory denoted by the first abstract pathname to
167     * the second abstract pathname, returning <code>true</code> if and only if
168     * the operation succeeds.
169     */
170    public abstract boolean rename(File f1, File f2);
171
172    /**
173     * Set the last-modified time of the file or directory denoted by the
174     * given abstract pathname, returning <code>true</code> if and only if the
175     * operation succeeds.
176     */
177    public abstract boolean setLastModifiedTime(File f, long time);
178
179    /**
180     * Mark the file or directory denoted by the given abstract pathname as
181     * read-only, returning <code>true</code> if and only if the operation
182     * succeeds.
183     */
184    public abstract boolean setReadOnly(File f);
185
186
187    /* -- Filesystem interface -- */
188
189    /**
190     * List the available filesystem roots.
191     */
192    public abstract File[] listRoots();
193
194    /* -- Disk usage -- */
195    public static final int SPACE_TOTAL  = 0;
196    public static final int SPACE_FREE   = 1;
197    public static final int SPACE_USABLE = 2;
198
199    public abstract long getSpace(File f, int t);
200    
201    /* -- Basic infrastructure -- */
202
203    /**
204     * Compare two abstract pathnames lexicographically.
205     */
206    public abstract int compare(File f1, File f2);
207
208    /**
209     * Compute the hash code of an abstract pathname.
210     */
211    public abstract int hashCode(File f);
212
213    // Flags for enabling/disabling performance optimizations for file
214    // name canonicalization
215    static boolean useCanonCaches      = true;
216    static boolean useCanonPrefixCache = true;
217
218    private static boolean getBooleanProperty(String prop, boolean defaultVal) {
219        String val = System.getProperty(prop);
220        if (val == null) return defaultVal;
221        if (val.equalsIgnoreCase("true")) {
222            return true;
223        } else {
224            return false;
225        }
226    }
227
228    static {
229        useCanonCaches      = getBooleanProperty("sun.io.useCanonCaches",
230                                                 useCanonCaches);
231        useCanonPrefixCache = getBooleanProperty("sun.io.useCanonPrefixCache",
232                                                 useCanonPrefixCache);
233    }
234}