| /* |
| * FileWatcher.java February 2008 |
| * |
| * Copyright (C) 2008, Niall Gallagher <niallg@users.sf.net> |
| * |
| * Licensed 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.simpleframework.common.buffer; |
| |
| import java.io.File; |
| import java.io.FileFilter; |
| import java.io.IOException; |
| |
| /** |
| * The <code>FileWatcher</code> object is used to create files that |
| * are to be used for file buffers. All files created by this are |
| * created in the <code>java.io.tmpdir</code> path. Temporary files |
| * created in this directory last for a configurable length of time |
| * before they are deleted. |
| * |
| * @author Niall Gallagher |
| */ |
| class FileWatcher implements FileFilter { |
| |
| /** |
| * This is the prefix for the temporary files created. |
| */ |
| private final String prefix; |
| |
| /** |
| * This is the duration the files created will exist for. |
| */ |
| private final long duration; |
| |
| /** |
| * Constructor for the <code>FileWatcher</code> object. This will |
| * allow temporary files to exist for five minutes. After this |
| * time the will be removed from the underlying directory. Any |
| * request for a new file will result in a sweep of the temporary |
| * directory for all matching files, if they have expired they |
| * will be deleted. |
| * |
| * @param prefix this is the file name prefix for the files |
| */ |
| public FileWatcher(String prefix) { |
| this(prefix, 300000); |
| } |
| |
| /** |
| * Constructor for the <code>FileWatcher</code> object. This will |
| * allow temporary files to exist for a configurable length of time. |
| * After this time the will be removed from the underlying directory. |
| * Any request for a new file will result in a sweep of the temporary |
| * directory for all matching files, if they have expired they |
| * will be deleted. |
| * |
| * @param prefix this is the file name prefix for the files |
| * @param duration this is the duration the files exist for |
| */ |
| public FileWatcher(String prefix, long duration) { |
| this.duration = duration; |
| this.prefix = prefix; |
| } |
| |
| /** |
| * This will create a temporary file which can be used as a buffer |
| * for <code>FileBuffer</code> objects. The file returned by this |
| * method will be created before it is returned, which ensures it |
| * can be used as a means to buffer bytes. All files are created |
| * in the <code>java.io.tmpdir</code> location, which represents |
| * the underlying file system temporary file destination. |
| * |
| * @return this returns a created temporary file for buffers |
| */ |
| public File create() throws IOException { |
| File path = create(prefix); |
| |
| if(!path.isDirectory()) { |
| File parent = path.getParentFile(); |
| |
| if(parent.isDirectory()) { |
| clean(parent); |
| } |
| } |
| return path; |
| } |
| |
| /** |
| * This will create a temporary file which can be used as a buffer |
| * for <code>FileBuffer</code> objects. The file returned by this |
| * method will be created before it is returned, which ensures it |
| * can be used as a means to buffer bytes. All files are created |
| * in the <code>java.io.tmpdir</code> location, which represents |
| * the underlying file system temporary file destination. |
| * |
| * @param prefix this is the prefix of the file to be created |
| * |
| * @return this returns a created temporary file for buffers |
| */ |
| private File create(String prefix) throws IOException { |
| File file = File.createTempFile(prefix, null); |
| |
| if(!file.exists()) { |
| file.createNewFile(); |
| } |
| return file; |
| } |
| |
| /** |
| * When this method is invoked the files that match the pattern |
| * of the temporary files are evaluated for deletion. Only those |
| * files that have not been modified in the duration period can |
| * be deleted. This ensures the file system is not exhausted. |
| * |
| * @param path this is the path of the file to be evaluated |
| */ |
| private void clean(File path) throws IOException { |
| File[] list = path.listFiles(this); |
| |
| for(File next : list) { |
| for(int i = 0; i < 3; i++) { |
| if(next.delete()) { |
| break; |
| } |
| } |
| } |
| } |
| |
| /** |
| * This determines if the file provided is an acceptable file for |
| * deletion. Acceptable files are those that match the pattern |
| * of files created by this file system object. If the file is |
| * a matching file then it is a candidate for deletion. |
| * |
| * @param file this is the file to evaluate for deletion |
| * |
| * @return this returns true if the file matches the pattern |
| */ |
| public boolean accept(File file) { |
| String name = file.getName(); |
| |
| if(file.isDirectory()) { |
| return false; |
| } |
| return accept(file, name); |
| } |
| |
| /** |
| * This determines if the file provided is an acceptable file for |
| * deletion. Acceptable files are those that match the pattern |
| * of files created by this file system object. If the file is |
| * a matching file then it is a candidate for deletion. |
| * |
| * @param file this is the file to evaluate for deletion |
| * @param name this is the name of the file to be evaluated |
| * |
| * @return this returns true if the file matches the pattern |
| */ |
| private boolean accept(File file, String name) { |
| long time = System.currentTimeMillis(); |
| long modified = file.lastModified(); |
| |
| if(modified + duration > time) { // not yet expired |
| return false; |
| } |
| return name.startsWith(prefix); |
| } |
| } |