Re: Stored Properties file gets emptied [follow up 2]

From:
Sabine Dinis Blochberger <no.spam@here.invalid>
Newsgroups:
comp.lang.java.help
Date:
Wed, 18 Nov 2009 12:28:00 GMT
Message-ID:
<9_adnaWHjNvSdZ7WnZ2dnUVZ8q2dnZ2d@novis.pt>
Sabine Dinis Blochberger wrote:

It seems there is a bug with our XMPP client (Java 1.6, smack) - I store
the users settings in a Properties file. My boss tells me on some
customers PCs the settings file sometimes ends up losing the contents.


There was a call to writeSettings in the applications shutdownHook that
I since changed. It was for saving the window position, so not critical.

Could it be that a try to write to the file in that circumstance could
lead to an empty or deleted file?

Rest of post quoted for completeness (no new text from me after).

I encapsulate the settings thusly:

public class Settings {
        
    public final static int DEF_SEC_PORT = 5223;
    public final static int DEF_PORT = 5222;
    // etc
    private boolean saveToFile = false;
    
    private Properties defaultProperties;
    private Properties userSettings;
    
    private String settingsDirName;
    private File settingsFile;
       
    /**
     * Creates a new instance of Settings.
     * @param settingsDir directory where to find/keep the
     * settings file.
     * when null, does not write a file
     */
    public Settings(String settingsDir) {
        
        if (settingsDir != null && !settingsDir.isEmpty()) {
            settingsDirName = settingsDir + "/" ;
            settingsFile = new File(settingsDirName +
                SETTINGS_FILE_NAME);
            saveToFile = true;
        } else saveToFile = false;
        
        // initialize default values
        defaultProperties = new Properties();
        defaultProperties.setProperty("autoAway", String.valueOf(true));
        defaultProperties.setProperty("autoAwayAfter",
            String.valueOf(5));
        defaultProperties.setProperty("identifyAsResource",
            DEFAULT_RESOURCE);
        //etc
        
        returnToDefaults();
        
        if (saveToFile) {
            if (!readSettingsFile()) {
                writeSettingsFile();
            }
        }
    }
    
    public final void returnToDefaults() {
        userSettings = new Properties(defaultProperties);
    }
    
    public boolean writeSettingsFile() {
        if (!saveToFile) return false;
        
        FileOutputStream out = null;
        try {
            // save settings
            out = new FileOutputStream(settingsFile);
            userSettings.store(out, "---Auto generated---");
            out.close();
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
            return false;
        } catch (IOException ex) {
            ex.printStackTrace();
            return false;
        }
        finally{
            if (out != null)
                try {
                    out.close();
                } catch (IOException ex) {
                    //ex.printStackTrace();
                }
        }
        return true;
    }
    
    public boolean readSettingsFile() {
        FileInputStream in = null;
        try {
            // read settings
            in = new FileInputStream(settingsFile);
            userSettings.load(in);
            in.close();
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
            return false;
        } catch (IOException ex) {
            ex.printStackTrace();
            return false;
        }
        finally {
            if (in != null)
                try {
                    in.close();
                } catch (IOException ex) {
                    //ex.printStackTrace();
                }
        }
        return true;
    }
        
    // main window position
    /** Returns last main window position */
    public final Point windowPosXY() {
      //snip
    }
    /** Sets last main window position.
      * @param pos position */
    public final void windowPosXY(Point pos) {
      //snip
    }
    // General settings
    /** Returns auto away on or off */
    public final boolean autoAway() {
        return Boolean.valueOf(userSettings.getProperty("autoAway",
                defaultProperties.getProperty("autoAway")));
    }
    /** Sets auto away setting.
     * @param autoAway turn on or off */
    public final void autoAway(boolean autoAway) {
        userSettings.setProperty("autoAway", String.valueOf(autoAway));
    }
  // etc

The class is instanciated in the application at start up with

 private static final String APP_HOME =
     System.getProperties().getProperty("appdir");
  private static final String USER_HOME =
     System.getProperties().getProperty("user.home");
  private static final String USER_APP_HOME = USER_HOME + "/op3mi";

    if (APP_HOME == null) {
        OPTIONS_DIRECTORY = new File(USER_APP_HOME, "/" +
            OPTIONS_DIR_NAME).getAbsoluteFile();
    } else {
        OPTIONS_DIRECTORY = new File(APP_HOME, "/" +
            OPTIONS_DIR_NAME).getAbsoluteFile();
    }
    appSettings = new Settings(OPTIONS_DIRECTORY.getAbsolutePath());

Thanks to any ideas in advance.


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