Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.camel.util; import java.io.File; import java.io.IOException; import java.util.Iterator; import java.util.Locale; import java.util.Random; import java.util.Stack; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * File utilities */ public final class FileUtil { private static final transient Log LOG = LogFactory.getLog(FileUtil.class); private static final int RETRY_SLEEP_MILLIS = 10; private static File defaultTempDir; private FileUtil() { } /** * Normalizes the path to cater for Windows and other platforms */ public static String normalizePath(String path) { if (path == null) { return null; } if (isWindows()) { // special handling for Windows where we need to convert / to \\ return path.replace('/', '\\'); } else { // for other systems make sure we use / as separators return path.replace('\\', '/'); } } public static boolean isWindows() { String osName = System.getProperty("os.name").toLowerCase(Locale.US); return osName.indexOf("windows") > -1; } public static File createTempFile(String prefix, String suffix) throws IOException { return createTempFile(prefix, suffix, null); } public static File createTempFile(String prefix, String suffix, File parentDir) throws IOException { File parent = (parentDir == null) ? getDefaultTempDir() : parentDir; if (suffix == null) { suffix = ".tmp"; } if (prefix == null) { prefix = "camel"; } else if (prefix.length() < 3) { prefix = prefix + "camel"; } // create parent folder parent.mkdirs(); return File.createTempFile(prefix, suffix, parent); } /** * Strip any leading separators */ public static String stripLeadingSeparator(String name) { if (name == null) { return null; } while (name.startsWith("/") || name.startsWith(File.separator)) { name = name.substring(1); } return name; } /** * Does the name start with a leading separator */ public static boolean hasLeadingSeparator(String name) { if (name == null) { return false; } if (name.startsWith("/") || name.startsWith(File.separator)) { return true; } return false; } /** * Strip first leading separator */ public static String stripFirstLeadingSeparator(String name) { if (name == null) { return null; } if (name.startsWith("/") || name.startsWith(File.separator)) { name = name.substring(1); } return name; } /** * Strip any trailing separators */ public static String stripTrailingSeparator(String name) { if (name == null) { return null; } while (name.endsWith("/") || name.endsWith(File.separator)) { name = name.substring(0, name.length() - 1); } return name; } /** * Strips any leading paths */ public static String stripPath(String name) { if (name == null) { return null; } int pos = name.lastIndexOf('/'); if (pos == -1) { pos = name.lastIndexOf(File.separator); } if (pos != -1) { return name.substring(pos + 1); } return name; } public static String stripExt(String name) { if (name == null) { return null; } int pos = name.lastIndexOf('.'); if (pos != -1) { return name.substring(0, pos); } return name; } /** * Returns only the leading path (returns <tt>null</tt> if no path) */ public static String onlyPath(String name) { if (name == null) { return null; } int pos = name.lastIndexOf('/'); if (pos == -1) { pos = name.lastIndexOf(File.separator); } if (pos > 0) { return name.substring(0, pos); } else if (pos == 0) { // name is in the root path, so extract the path as the first char return name.substring(0, 1); } // no path in name return null; } /** * Compacts a path by stacking it and reducing <tt>..</tt> */ public static String compactPath(String path) { if (path == null) { return null; } // only normalize path if it contains .. as we want to avoid: path/../sub/../sub2 as this can leads to trouble if (path.indexOf("..") == -1) { return path; } // only normalize if contains a path separator if (path.indexOf(File.separator) == -1) { return path; } Stack<String> stack = new Stack<String>(); String separatorRegex = File.separator; if (FileUtil.isWindows()) { separatorRegex = "\\\\"; } String[] parts = path.split(separatorRegex); for (String part : parts) { if (part.equals("..") && !stack.isEmpty()) { // only pop if there is a previous path stack.pop(); } else { stack.push(part); } } // build path based on stack StringBuilder sb = new StringBuilder(); for (Iterator<String> it = stack.iterator(); it.hasNext();) { sb.append(it.next()); if (it.hasNext()) { sb.append(File.separator); } } return sb.toString(); } private static synchronized File getDefaultTempDir() { if (defaultTempDir != null && defaultTempDir.exists()) { return defaultTempDir; } String s = System.getProperty("java.io.tmpdir"); File checkExists = new File(s); if (!checkExists.exists()) { throw new RuntimeException("The directory " + checkExists.getAbsolutePath() + " does not exist, please set java.io.tempdir" + " to an existing directory"); } // create a sub folder with a random number Random ran = new Random(); int x = ran.nextInt(1000000); File f = new File(s, "camel-tmp-" + x); while (!f.mkdir()) { x = ran.nextInt(1000000); f = new File(s, "camel-tmp-" + x); } defaultTempDir = f; // create shutdown hook to remove the temp dir Thread hook = new Thread() { @Override public void run() { removeDir(defaultTempDir); } }; Runtime.getRuntime().addShutdownHook(hook); return defaultTempDir; } private static void removeDir(File d) { String[] list = d.list(); if (list == null) { list = new String[0]; } for (String s : list) { File f = new File(d, s); if (f.isDirectory()) { removeDir(f); } else { delete(f); } } delete(d); } private static void delete(File f) { if (!f.delete()) { if (isWindows()) { System.gc(); } try { Thread.sleep(RETRY_SLEEP_MILLIS); } catch (InterruptedException ex) { // Ignore Exception } if (!f.delete()) { f.deleteOnExit(); } } } public static boolean renameFile(File from, File to) { // do not try to rename non existing files if (!from.exists()) { return false; } // some OS such as Windows can have problem doing rename IO operations so we may need to // retry a couple of times to let it work boolean renamed = false; int count = 0; while (!renamed && count < 3) { if (LOG.isDebugEnabled() && count > 0) { LOG.debug("Retrying attempt " + count + " to rename file from: " + from + " to: " + to); } renamed = from.renameTo(to); if (!renamed && count > 0) { try { Thread.sleep(1000); } catch (InterruptedException e) { // ignore } } count++; } if (LOG.isDebugEnabled() && count > 0) { LOG.debug("Tried " + count + " to rename file: " + from + " to: " + to + " with result: " + renamed); } return renamed; } public static boolean deleteFile(File file) { // do not try to delete non existing files if (!file.exists()) { return false; } // some OS such as Windows can have problem doing delete IO operations so we may need to // retry a couple of times to let it work boolean deleted = false; int count = 0; while (!deleted && count < 3) { if (LOG.isDebugEnabled() && count > 0) { LOG.debug("Retrying attempt " + count + " to delete file: " + file); } deleted = file.delete(); if (!deleted && count > 0) { try { Thread.sleep(1000); } catch (InterruptedException e) { // ignore } } count++; } if (LOG.isDebugEnabled() && count > 0) { LOG.debug("Tried " + count + " to delete file: " + file + " with result: " + deleted); } return deleted; } /** * Is the given file an absolute file. * <p/> * Will also work around issue on Windows to consider files on Windows starting with a \ * as absolute files. This makes the logic consistent across all OS platforms. * * @param file the file * @return <tt>true</ff> if its an absolute path, <tt>false</tt> otherwise. */ public static boolean isAbsolute(File file) { if (isWindows()) { // special for windows String path = file.getPath(); if (path.startsWith(File.separator)) { return true; } } return file.isAbsolute(); } }