symlink.java

java ant的源码！非常值得看的源码

     * Set overwrite mode. If set to false (default)
     * the task will not overwrite existing links, and may stop the build
     * if a link already exists depending on the setting of failonerror.
     *
     * @param owrite If true overwrite existing links.
     */
    public void setOverwrite(boolean owrite) {
        this.overwrite = owrite;
    }

    /**
     * Set failonerror mode. If set to true (default) the entire build fails
     * upon error; otherwise the error is logged and the build will continue.
     *
     * @param foe    If true throw BuildException on error, else log it.
     */
    public void setFailOnError(boolean foe) {
        this.failonerror = foe;
    }

    /**
     * Set the action to be performed.  May be "single",
     * "delete", "recreate" or "record".
     *
     * @param action    The action to perform.
     */
    public void setAction(String action) {
        super.setAction(action);
    }

    /**
     * Set the name of the link. Used when action = "single".
     *
     * @param lnk     The name for the link.
     */
    public void setLink(String lnk) {
        this.link = lnk;
    }

    /**
     * Set the name of the resource to which a link should be created.
     * Used when action = "single".
     *
     * @param src      The resource to be linked.
     */
    public void setResource(String src) {
        this.resource = src;
    }

    /**
     * Set the name of the file to which links will be written.
     * Used when action = "record".
     *
     * @param lf      The name of the file to write links to.
     */
    public void setLinkfilename(String lf) {
        this.linkFileName = lf;
    }

    /**
     * Add a fileset to this task.
     *
     * @param set      The fileset to add.
     */
    public void addFileset(FileSet set) {
        fileSets.addElement(set);
    }

    /**
     * Delete a symlink (without deleting the associated resource).
     *
     * <p>This is a convenience method that simply invokes
     * <code>deleteSymlink(java.io.File)</code>.
     *
     * @param path    A string containing the path of the symlink to delete.
     *
     * @throws FileNotFoundException   When the path results in a
     *                                   <code>File</code> that doesn't exist.
     * @throws IOException             If calls to <code>File.rename</code>
     *                                   or <code>File.delete</code> fail.
     */
    public static void deleteSymlink(String path)
        throws IOException, FileNotFoundException {
        deleteSymlink(new File(path));
    }

    /**
     * Delete a symlink (without deleting the associated resource).
     *
     * <p>This is a utility method that removes a unix symlink without removing
     * the resource that the symlink points to. If it is accidentally invoked
     * on a real file, the real file will not be harmed, but an exception
     * will be thrown when the deletion is attempted. This method works by
     * getting the canonical path of the link, using the canonical path to
     * rename the resource (breaking the link) and then deleting the link.
     * The resource is then returned to its original name inside a finally
     * block to ensure that the resource is unharmed even in the event of
     * an exception.
     *
     * @param linkfil    A <code>File</code> object of the symlink to delete.
     *
     * @throws FileNotFoundException   When the path results in a
     *                                   <code>File</code> that doesn't exist.
     * @throws IOException             If calls to <code>File.rename</code>,
     *                                   <code>File.delete</code> or
     *                                   <code>File.getCanonicalPath</code>
     *                                   fail.
     */
    public static void deleteSymlink(File linkfil)
        throws IOException, FileNotFoundException {
        if (!linkfil.exists()) {
            throw new FileNotFoundException("No such symlink: " + linkfil);
        }
        // find the resource of the existing link:
        File canfil = linkfil.getCanonicalFile();

        // rename the resource, thus breaking the link:
        File temp = FILE_UTILS.createTempFile("symlink", ".tmp",
                                              canfil.getParentFile());
        try {
            try {
                FILE_UTILS.rename(canfil, temp);
            } catch (IOException e) {
                throw new IOException(
                    "Couldn't rename resource when attempting to delete "
                    + linkfil);
            }
            // delete the (now) broken link:
            if (!linkfil.delete()) {
                throw new IOException("Couldn't delete symlink: " + linkfil
                    + " (was it a real file? is this not a UNIX system?)");
            }
        } finally {
            // return the resource to its original name:
            try {
                FILE_UTILS.rename(temp, canfil);
            } catch (IOException e) {
                throw new IOException("Couldn't return resource " + temp
                    + " to its original name: " + canfil.getAbsolutePath()
                    + "\n THE RESOURCE'S NAME ON DISK HAS "
                    + "BEEN CHANGED BY THIS ERROR!\n");
            }
        }
    }

    /**
     * Write a properties file. This method uses <code>Properties.store</code>
     * and thus may throw exceptions that occur while writing the file.
     *
     * @param properties     The properties object to be written.
     * @param dir            The directory for which we are writing the links.
     */
    private void writePropertyFile(Properties properties, File dir)
        throws BuildException {
        BufferedOutputStream bos = null;
        try {
            bos = new BufferedOutputStream(
                new FileOutputStream(new File(dir, linkFileName)));
            properties.store(bos, "Symlinks from " + dir);
        } catch (IOException ioe) {
            throw new BuildException(ioe, getLocation());
        } finally {
            FileUtils.close(bos);
        }
    }

    /**
     * Handle errors based on the setting of failonerror.
     *
     * @param msg    The message to log, or include in the
     *                  <code>BuildException</code>.
     */
    private void handleError(String msg) {
        if (failonerror) {
            throw new BuildException(msg);
        }
        log(msg);
    }

    /**
     * Conduct the actual construction of a link.
     *
     * <p> The link is constructed by calling <code>Execute.runCommand</code>.
     *
     * @param res   The path of the resource we are linking to.
     * @param lnk       The name of the link we wish to make.
     */
    private void doLink(String res, String lnk) throws BuildException {
        File linkfil = new File(lnk);
        if (overwrite && linkfil.exists()) {
            try {
                deleteSymlink(linkfil);
            } catch (FileNotFoundException fnfe) {
                handleError("Symlink disappeared before it was deleted: " + lnk);
            } catch (IOException ioe) {
                handleError("Unable to overwrite preexisting link: " + lnk);
            }
        }
        String[] cmd = new String[] {"ln", "-s", res, lnk};
        log(Commandline.toString(cmd));
        Execute.runCommand(this, cmd);
    }

    /**
     * Find all the links in all supplied filesets.
     *
     * <p> This method is invoked when the action attribute is
     * &quot;record&quot;. This means that filesets are interpreted
     * as the directories in which links may be found.
     *
     * @param v   The filesets specified by the user.
     * @return A HashSet of <code>File</code> objects containing the
     *         links (with canonical parent directories).
     */
    private HashSet findLinks(Vector v) {
        HashSet result = new HashSet();
        for (int i = 0; i < v.size(); i++) {
            FileSet fs = (FileSet) v.get(i);
            DirectoryScanner ds = fs.getDirectoryScanner(getProject());
            String[][] fnd = new String[][]
                {ds.getIncludedFiles(), ds.getIncludedDirectories()};
            File dir = fs.getDir(getProject());
            for (int j = 0; j < fnd.length; j++) {
                for (int k = 0; k < fnd[j].length; k++) {
                    try {
                        File f = new File(dir, fnd[j][k]);
                        File pf = f.getParentFile();
                        String name = f.getName();
                        if (FILE_UTILS.isSymbolicLink(pf, name)) {
                            result.add(new File(pf.getCanonicalFile(), name));
                        }
                    } catch (IOException e) {
                        handleError("IOException: " + fnd[j][k] + " omitted");
                    }
                }
            }
        }
        return result;
    }

    /**
     * Load links from properties files included in one or more FileSets.
     *
     * <p> This method is only invoked when the action attribute is set to
     * &quot;recreate&quot;. The filesets passed in are assumed to specify the
     * names of the property files with the link information and the
     * subdirectories in which to look for them.
     *
     * @param v    The <code>FileSet</code>s for this task.
     * @return            The links to be made.
     */
    private Properties loadLinks(Vector v) {
        Properties finalList = new Properties();
        // loop through the supplied file sets:
        for (int i = 0; i < v.size(); i++) {
            FileSet fs = (FileSet) v.elementAt(i);
            DirectoryScanner ds = new DirectoryScanner();
            fs.setupDirectoryScanner(ds, getProject());
            ds.setFollowSymlinks(false);
            ds.scan();
            String[] incs = ds.getIncludedFiles();
            File dir = fs.getDir(getProject());

            // load included files as properties files:
            for (int j = 0; j < incs.length; j++) {
                File inc = new File(dir, incs[j]);
                File pf = inc.getParentFile();
                Properties lnks = new Properties();
                try {
                    lnks.load(new BufferedInputStream(new FileInputStream(inc)));
                    pf = pf.getCanonicalFile();
                } catch (FileNotFoundException fnfe) {
                    handleError("Unable to find " + incs[j] + "; skipping it.");
                    continue;
                } catch (IOException ioe) {
                    handleError("Unable to open " + incs[j]
                                + " or its parent dir; skipping it.");
                    continue;
                }
                lnks.list(new PrintStream(
                    new LogOutputStream(this, Project.MSG_INFO)));
                // Write the contents to our master list of links
                // This method assumes that all links are defined in
                // terms of absolute paths, or paths relative to the
                // working directory:
                for (Iterator kitr = lnks.keySet().iterator(); kitr.hasNext();) {
                    String key = (String) kitr.next();
                    finalList.put(new File(pf, key).getAbsolutePath(),
                        lnks.getProperty(key));
                }
            }
        }
        return finalList;
    }
}