preferencestore.java

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/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.preference;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Properties;

import org.eclipse.core.commands.common.EventManager;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.util.Assert;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jface.util.SafeRunnable;

/**
 * A concrete preference store implementation based on an internal
 * <code>java.util.Properties</code> object, with support for persisting the
 * non-default preference values to files or streams.
 * <p>
 * This class was not designed to be subclassed.
 * </p>
 * 
 * @see IPreferenceStore
 */
public class PreferenceStore extends EventManager implements
		IPersistentPreferenceStore {

    /**
     * The mapping from preference name to preference value (represented as
     * strings).
     */
    private Properties properties;

    /**
     * The mapping from preference name to default preference value (represented
     * as strings); <code>null</code> if none.
     */
    private Properties defaultProperties;

    /**
     * Indicates whether a value as been changed by <code>setToDefault</code>
     * or <code>setValue</code>; initially <code>false</code>.
     */
    private boolean dirty = false;

    /**
     * The file name used by the <code>load</code> method to load a property
     * file. This filename is used to save the properties file when
     * <code>save</code> is called.
     */
    private String filename;

    /**
     * Creates an empty preference store.
     * <p>
     * Use the methods <code>load(InputStream)</code> and
     * <code>save(InputStream)</code> to load and store this preference store.
     * </p>
     * 
     * @see #load(InputStream)
     * @see #save(OutputStream, String)
     */
    public PreferenceStore() {
        defaultProperties = new Properties();
        properties = new Properties(defaultProperties);
    }

    /**
     * Creates an empty preference store that loads from and saves to the a
     * file.
     * <p>
     * Use the methods <code>load()</code> and <code>save()</code> to load
     * and store this preference store.
     * </p>
     * 
     * @param filename
     *            the file name
     * @see #load()
     * @see #save()
     */
    public PreferenceStore(String filename) {
        this();
        Assert.isNotNull(filename);
        this.filename = filename;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public void addPropertyChangeListener(IPropertyChangeListener listener) {
        addListenerObject(listener);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public boolean contains(String name) {
        return (properties.containsKey(name) || defaultProperties
                .containsKey(name));
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public void firePropertyChangeEvent(String name, Object oldValue,
            Object newValue) {
        final Object[] finalListeners = getListeners();
        // Do we need to fire an event.
        if (finalListeners.length > 0
                && (oldValue == null || !oldValue.equals(newValue))) {
            final PropertyChangeEvent pe = new PropertyChangeEvent(this, name,
                    oldValue, newValue);
            for (int i = 0; i < finalListeners.length; ++i) {
                final IPropertyChangeListener l = (IPropertyChangeListener) finalListeners[i];
                SafeRunnable.run(new SafeRunnable(JFaceResources.getString("PreferenceStore.changeError")) { //$NON-NLS-1$
                		public void run() {
  			                l.propertyChange(pe);
                		}
                });
            }
        }
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public boolean getBoolean(String name) {
        return getBoolean(properties, name);
    }

    /**
     * Helper function: gets boolean for a given name.
     * 
     * @param p
     * @param name
     * @return boolean
     */
    private boolean getBoolean(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return BOOLEAN_DEFAULT_DEFAULT;
		}
        if (value.equals(IPreferenceStore.TRUE)) {
			return true;
		}
        return false;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public boolean getDefaultBoolean(String name) {
        return getBoolean(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public double getDefaultDouble(String name) {
        return getDouble(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public float getDefaultFloat(String name) {
        return getFloat(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public int getDefaultInt(String name) {
        return getInt(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public long getDefaultLong(String name) {
        return getLong(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public String getDefaultString(String name) {
        return getString(defaultProperties, name);
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public double getDouble(String name) {
        return getDouble(properties, name);
    }

    /**
     * Helper function: gets double for a given name.
     * 
     * @param p
     * @param name
     * @return double
     */
    private double getDouble(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return DOUBLE_DEFAULT_DEFAULT;
		}
        double ival = DOUBLE_DEFAULT_DEFAULT;
        try {
            ival = new Double(value).doubleValue();
        } catch (NumberFormatException e) {
        }
        return ival;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public float getFloat(String name) {
        return getFloat(properties, name);
    }

    /**
     * Helper function: gets float for a given name.
     * @param p
     * @param name
     * @return float
     */
    private float getFloat(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return FLOAT_DEFAULT_DEFAULT;
		}
        float ival = FLOAT_DEFAULT_DEFAULT;
        try {
            ival = new Float(value).floatValue();
        } catch (NumberFormatException e) {
        }
        return ival;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public int getInt(String name) {
        return getInt(properties, name);
    }

    /**
     * Helper function: gets int for a given name.
     * @param p
     * @param name
     * @return int
     */
    private int getInt(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return INT_DEFAULT_DEFAULT;
		}
        int ival = 0;
        try {
            ival = Integer.parseInt(value);
        } catch (NumberFormatException e) {
        }
        return ival;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public long getLong(String name) {
        return getLong(properties, name);
    }

    /**
     * Helper function: gets long for a given name.
     * @param p
     * @param name
     * @return
     */
    private long getLong(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return LONG_DEFAULT_DEFAULT;
		}
        long ival = LONG_DEFAULT_DEFAULT;
        try {
            ival = Long.parseLong(value);
        } catch (NumberFormatException e) {
        }
        return ival;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public String getString(String name) {
        return getString(properties, name);
    }

    /**
     * Helper function: gets string for a given name.
     * @param p
     * @param name
     * @return
     */
    private String getString(Properties p, String name) {
        String value = p != null ? p.getProperty(name) : null;
        if (value == null) {
			return STRING_DEFAULT_DEFAULT;
		}
        return value;
    }

    /*
     * (non-Javadoc) Method declared on IPreferenceStore.
     */
    public boolean isDefault(String name) {
        return (!properties.containsKey(name) && defaultProperties
                .containsKey(name));
    }

    /**
     * Prints the contents of this preference store to the given print stream.