com.totsp.gwittir.client.util.WindowContext.java Source code

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Here is the source code for com.totsp.gwittir.client.util.WindowContext.java

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/*
 * Created on August 3, 2007, 3:40 PM
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package com.totsp.gwittir.client.util;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import com.google.gwt.core.client.GWT;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.WindowCloseListener;
import com.totsp.gwittir.client.log.Level;
import com.totsp.gwittir.client.log.Logger;
import com.totsp.gwittir.client.util.impl.WindowContextPersister;
import com.totsp.gwittir.client.util.impl.WindowContextPersisterMacShell;

/**
 * The WindowContext class is a front end for abstract client storage, allowing for the storage of
 * key/value pairs that persist on the client between browser sessions.
 * 
 * It is built on top of the other persistence systems in the client.util package and fails down (with
 * availablility from Gears to MSIE UserData, to FireFox/Opera DOMStorage (and in the future to Flash LSO).
 * 
 * @author <a href="cooper@screaming-penguin.com">Robert "kebernet" Cooper</a>
 */
public class WindowContext {

    /** 
     * The static instance of the WindowContext object.
     */
    private static final Logger LOG = Logger.getLogger(WindowContext.class.getName());
    public static final WindowContext INSTANCE = new WindowContext();
    private final Map<String, String> data = new HashMap<String, String>();
    private WindowContextPersister persister = (WindowContextPersister) GWT.create(WindowContextPersister.class);
    private boolean initialized = false;
    private int flushed = 0;
    private final WindowCloseListener wcl = new WindowCloseListener() {
        public String onWindowClosing() {
            flush();
            flushed = 1;
            return null;
        }

        public void onWindowClosed() {

        }
    };

    private WindowContext() {
        super();
        Window.addWindowCloseListener(wcl);
        Window.setStatus(this.instrumentModuleFrame());

    }

    private native String instrumentModuleFrame() /*-{
                                                  var instance = this;
                                                  if($wnd != window){
                                                  window.onunload = function(){
                                                  try{
                                                  //alert("flush");
                                                  instance.@com.totsp.gwittir.client.util.WindowContext::flush()();
                                                  } catch(e) {
                                                  alert(e);
                                                  }
                                                  }
                                                      
                                                  }
                                                  return $wnd.__gwittir_storage;
                                                  }-*/;

    /** 
     * Immediately writes the values in the context to whatever the persistent store is. This
     * will happen automatically during onWindowClosing(); Final storage may or may not be synchronous
     * to the call of the flush() method.
     */
    public void flush() {
        if (flushed != 1) {
            persister.storeWindowContextData(data);
            LOG.log(Level.INFO, "Flushed " + data.size() + " items.", null);
        }
    }

    /**
     * Initializes the WindowContext. Takes in a call back that will be notified when the
     * initialization procedure is complete. This will *always* take place off the execution 
     * context of the call to initialize, whether the individual persistence mechanism is asynchronous
     * or not.
     * 
     * Calls to initialize after the first will be ignored.
     * 
     * @param callback WindowContextCallback to notify when the WindowContext has been initialized. 
     */
    public void initialize(final WindowContextCallback callback) {
        //      if(!GWT.isScript() && getUserAgent().indexOf("WebKit") != -1){
        //         this.persister = new WindowContextPersisterMacShell();
        //         LOG.log(Level.WARN, "***You are in hosted mode on Safari. Defaulting to the WindowName persister because HTML5 won't work in hosted mode!***", null);
        //      }
        LOG.log(Level.INFO, "Got persister :" + persister.getClass(), null);
        WindowContextCallback internalCallback = new WindowContextCallback() {

            public void onInitialized() {
                data.putAll(persister.getWindowContextData());
                initialized = true;
                LOG.log(Level.DEBUG, "Initialized.", null);
                callback.onInitialized();
            }

        };
        persister.init(internalCallback);
    }

    /**
     * Gets the value of a key
     * @param key The key value to lookup
     * @return a value or null
     */
    public String get(String key) {
        return data.get(key);
    }

    /**
     * Inserts a new value into the dataset
     * @param key the key to insert. Keys should contain ONLY alphanumeric characters.
     * @param item the new value to insert.
     */
    public void put(String key, String item) {
        assert key.matches("[a-zA-Z0-9]*") : "Illegal character in the key";
        LOG.log(Level.DEBUG, "set [" + key + ":" + item + "]", null);
        data.put(key, item);
    }

    public Set<String> keySet() {
        return data.keySet();
    }

    /**
     * An interface to implement to receive notification of when the WindowContext has been initialized.
     * 
     */
    public static interface WindowContextCallback {

        /**
         * Called asynchronously when the WindowContext is ready for use.
         */
        void onInitialized();
    }

    public static native String getUserAgent()
    /*-{return navigator.userAgent; }-*/;

    public boolean isInitialized() {
        return this.initialized;
    }
}