source: src/main/java/weka/gui/SaveBuffer.java @ 18

/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    SaveBuffer.java
 *    Copyright (C) 2000 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.gui;

import weka.gui.Logger;

import java.io.File;
import java.io.FileWriter;
import java.io.Writer;
import java.io.BufferedWriter;
import java.io.PrintWriter;

import java.awt.Component;
import javax.swing.JFileChooser;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JDialog;

/**
 * This class handles the saving of StringBuffers to files. It will pop
 * up a file chooser allowing the user to select a destination file. If
 * the file exists, the user is prompted for the correct course of action,
 * ie. overwriting, appending, selecting a new filename or canceling.
 *
 * @author Mark Hall (mhall@cs.waikato.ac.nz)
 * @version $Revision 1.0 $
 */
public class SaveBuffer {

  /** The Logger to send messages to */
  private Logger m_Log;

  /** The parent component requesting the save */
  private Component m_parentComponent;

  /** Last directory selected from the file chooser */
  private String m_lastvisitedDirectory=null;

  /**
   * Constructor
   * @param log the logger to send messages to
   * @param parent the parent component will be requesting a save
   */
  public SaveBuffer(Logger log, Component parent) {
    m_Log = log;
    m_parentComponent = parent;
  }

  /**
   * Save a buffer
   * @param buf the buffer to save
   * @return true if the save is completed succesfully
   */
  public boolean save(StringBuffer buf) {
    if (buf != null) {
      JFileChooser fileChooser;
      if (m_lastvisitedDirectory == null) {
        fileChooser = new JFileChooser(
                      new File(System.getProperty("user.dir")));
      } else {
        fileChooser = new JFileChooser(m_lastvisitedDirectory);
      }

      fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
      int returnVal = fileChooser.showSaveDialog(m_parentComponent);
      if (returnVal == JFileChooser.APPROVE_OPTION) {
        File sFile = fileChooser.getSelectedFile();
        m_lastvisitedDirectory = sFile.getPath();

        if (sFile.exists()) {
          Object [] options = new String[4];
          options[0] = "Append";
          options[1] = "Overwrite";
          options[2] = "Choose new name";
          options[3] = "Cancel";
        
          JOptionPane jop = new JOptionPane("File exists",
                                             JOptionPane.QUESTION_MESSAGE,
                                            1,
                                            null,
                                            options);
          JDialog dialog = jop.createDialog(m_parentComponent, "File query");
          dialog.setVisible(true);
          Object selectedValue = jop.getValue();
          if (selectedValue == null) {
          } else {
            for(int i=0; i<4; i++) {
              if(options[i].equals(selectedValue)) {
                switch (i) {
                  // append
                case 0:
                  return saveOverwriteAppend(buf, sFile, true);
                  // overwrite
                case 1: 
                  return saveOverwriteAppend(buf, sFile, false);
                  // pick new name
                case 2:
                  return save(buf);
                  // cancel
                case 3: break;
                }
              }
            }
          }
        } else {
          saveOverwriteAppend(buf, sFile, false); // file does not exist
        }
      } else {
        return false; // file save canceled
      }
    }
    return false; // buffer null
  }

  /** 
   * Saves the provided buffer to the specified file
   * @param buf the buffer to save
   * @param sFile the file to save to
   * @param append true if buffer is to be appended to file
   * @return true if save is succesful
   */
  private boolean saveOverwriteAppend(StringBuffer buf, 
                                      File sFile,
                                      boolean append) {

    try {
      String path = sFile.getPath();
      if (m_Log != null) {
        if (append) {
          m_Log.statusMessage("Appending to file...");
        } else {
          m_Log.statusMessage("Saving to file...");
        }
      }
      PrintWriter out
        = new PrintWriter(new BufferedWriter(
                          new FileWriter(path, append)));
      out.write(buf.toString(),0,buf.toString().length());
      out.close();
      if (m_Log != null) {
        m_Log.statusMessage("OK");
      }
    } catch (Exception ex) {
      ex.printStackTrace();
      if (m_Log != null) {
        m_Log.logMessage(ex.getMessage());
      }
      return false;
    }

    return true;
  }

  /**
   * Main method for testing this class
   */
  public static void main(String [] args) {
     try {
       final javax.swing.JFrame jf =
         new javax.swing.JFrame("SaveBuffer test");
      jf.getContentPane().setLayout(new java.awt.BorderLayout());
      weka.gui.LogPanel lp = new weka.gui.LogPanel();
      javax.swing.JButton jb = new javax.swing.JButton("Save");
      jf.getContentPane().add(jb,java.awt.BorderLayout.SOUTH);
      jf.getContentPane().add(lp, java.awt.BorderLayout.CENTER);
      final SaveBuffer svb = new SaveBuffer(lp, jf);
      jb.addActionListener(new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent e) {
            svb.save(new StringBuffer("A bit of test text"));
          }
        });

      jf.addWindowListener(new java.awt.event.WindowAdapter() {
          public void windowClosing(java.awt.event.WindowEvent e) {
            jf.dispose();
            System.exit(0);
          }
        });
      jf.pack();
      jf.setVisible(true);
     } catch (Exception ex) {
       ex.printStackTrace();
       System.err.println(ex.getMessage());
     }
  }
}