/* * 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.log4j.lf5.viewer.configure;import java.io.*;import java.net.URL;import java.util.Iterator;import java.util.LinkedList;/** * <p>MRUFileManager handles the storage and retrival the most * recently opened log files. * * @author Brad Marlborough * @author Richard Hurst */// Contributed by ThoughtWorks Inc.public class MRUFileManager {  //--------------------------------------------------------------------------  //   Constants:  //--------------------------------------------------------------------------  private static final String CONFIG_FILE_NAME = "mru_file_manager";  private static final int DEFAULT_MAX_SIZE = 3;  //--------------------------------------------------------------------------  //   Protected Variables:  //--------------------------------------------------------------------------  //--------------------------------------------------------------------------  //   Private Variables:  //--------------------------------------------------------------------------  private int _maxSize = 0;  private LinkedList _mruFileList;  //--------------------------------------------------------------------------  //   Constructors:  //--------------------------------------------------------------------------  public MRUFileManager() {    load();    setMaxSize(DEFAULT_MAX_SIZE);  }  public MRUFileManager(int maxSize) {    load();    setMaxSize(maxSize);  }  //--------------------------------------------------------------------------  //   Public Methods:  //--------------------------------------------------------------------------  /**   * Saves a list of MRU files out to a file.   */  public void save() {    File file = new File(getFilename());    try {      ObjectOutputStream oos = new ObjectOutputStream(new          FileOutputStream(file));      oos.writeObject(_mruFileList);      oos.flush();      oos.close();    } catch (Exception e) {      // do nothing      e.printStackTrace();    }  }  /**   * Gets the size of the MRU file list.   */  public int size() {    return _mruFileList.size();  }  /**   * Returns a particular file name stored in a MRU file   * list based on an index value.   */  public Object getFile(int index) {    if (index < size()) {      return _mruFileList.get(index);    }    return null;  }  /**   * Returns a input stream to the resource at the specified index   */  public InputStream getInputStream(int index) throws IOException,      FileNotFoundException {    if (index < size()) {      Object o = getFile(index);      if (o instanceof File) {        return getInputStream((File) o);      } else {        return getInputStream((URL) o);      }    }    return null;  }  /**   * Adds a file name to the MRU file list.   */  public void set(File file) {    setMRU(file);  }  /**   * Adds a url to the MRU file list.   */  public void set(URL url) {    setMRU(url);  }  /**   * Gets the list of files stored in the MRU file list.   */  public String[] getMRUFileList() {    if (size() == 0) {      return null;    }    String[] ss = new String[size()];    for (int i = 0; i < size(); i++) {      Object o = getFile(i);      if (o instanceof File) {        ss[i] = ((File) o).getAbsolutePath();      } else // must be a url      {        ss[i] = o.toString();      }    }    return ss;  }  /**   * Moves the the index to the top of the MRU List   *   * @param index The index to be first in the mru list   */  public void moveToTop(int index) {    _mruFileList.add(0, _mruFileList.remove(index));  }  /**   * Creates the directory where the MRU file list will be written.   * The "lf5" directory is created in the Documents and Settings   * directory on Windows 2000 machines and where ever the user.home   * variable points on all other platforms.   */  public static void createConfigurationDirectory() {    String home = System.getProperty("user.home");    String sep = System.getProperty("file.separator");    File f = new File(home + sep + "lf5");    if (!f.exists()) {      try {        f.mkdir();      } catch (SecurityException e) {        e.printStackTrace();      }    }  }  //--------------------------------------------------------------------------  //   Protected Methods:  //--------------------------------------------------------------------------  /**   * Gets an input stream for the corresponding file.   *   * @param file The file to create the input stream from.   * @return InputStream   */  protected InputStream getInputStream(File file) throws IOException,      FileNotFoundException {    BufferedInputStream reader =        new BufferedInputStream(new FileInputStream(file));    return reader;  }  /**   * Gets an input stream for the corresponding URL.   *   * @param url The url to create the input stream from.   * @return InputStream   */  protected InputStream getInputStream(URL url) throws IOException {    return url.openStream();  }  /**   * Adds an object to the mru.   */  protected void setMRU(Object o) {    int index = _mruFileList.indexOf(o);    if (index == -1) {      _mruFileList.add(0, o);      setMaxSize(_maxSize);    } else {      moveToTop(index);    }  }  /**   * Loads the MRU file list in from a file and stores it in a LinkedList.   * If no file exists, a new LinkedList is created.   */  protected void load() {    createConfigurationDirectory();    File file = new File(getFilename());    if (file.exists()) {      try {        ObjectInputStream ois = new ObjectInputStream(            new FileInputStream(file));        _mruFileList = (LinkedList) ois.readObject();        ois.close();        // check that only files and url are in linked list        Iterator it = _mruFileList.iterator();        while (it.hasNext()) {          Object o = it.next();          if (!(o instanceof File) && !(o instanceof URL)) {            it.remove();          }        }      } catch (Exception e) {        _mruFileList = new LinkedList();      }    } else {      _mruFileList = new LinkedList();    }  }  protected String getFilename() {    String home = System.getProperty("user.home");    String sep = System.getProperty("file.separator");    return home + sep + "lf5" + sep + CONFIG_FILE_NAME;  }  /**   * Ensures that the MRU list will have a MaxSize.   */  protected void setMaxSize(int maxSize) {    if (maxSize < _mruFileList.size()) {      for (int i = 0; i < _mruFileList.size() - maxSize; i++) {        _mruFileList.removeLast();      }    }    _maxSize = maxSize;  }  //--------------------------------------------------------------------------  //   Private Methods:  //--------------------------------------------------------------------------  //--------------------------------------------------------------------------  //   Nested Top-Level Classes or Interfaces  //--------------------------------------------------------------------------}