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World Wind is a collection of components that interactively display 3D geographic information within Java applications or applets.
/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwindx.examples.util;
import gov.nasa.worldwind.*;
import gov.nasa.worldwind.layers.*;
import gov.nasa.worldwind.util.*;
import java.io.File;
import java.lang.reflect.Constructor;
import java.util.*;
import java.util.logging.Level;
/**
* @author dcollins
* @version $Id: SessionState.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class SessionState
{
protected static class LayerStateFilename
{
protected String className;
protected int index;
public LayerStateFilename(String className, int index)
{
this.className = className;
this.index = index;
}
}
protected static final String VIEW_STATE_PATH = "SessionState/ViewState.xml";
protected static final String LAYER_STATE_PATH = "SessionState/LayerState";
protected static final String LAYER_STATE_FILENAME_DELIMITER = "-";
protected static final Comparator LAYER_STATE_FILENAME_COMPARATOR = new Comparator()
{
@Override
public int compare(String a, String b)
{
LayerStateFilename fna = parseLayerStateFilename(a);
LayerStateFilename fnb = parseLayerStateFilename(b);
if (fna == null || fnb == null)
return fnb != null ? -1 : (fna != null ? 1 : 0);
else
return fna.index < fnb.index ? -1 : (fna.index > fnb.index ? 1 : 0);
}
};
protected String sessionKey;
public SessionState(String sessionKey)
{
if (WWUtil.isEmpty(sessionKey))
{
String msg = Logging.getMessage("nullValue.KeyIsNull");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
this.sessionKey = sessionKey;
}
public String getSessionKey()
{
return this.sessionKey;
}
public void saveSessionState(WorldWindow worldWindow)
{
if (worldWindow == null)
{
String msg = Logging.getMessage("nullValue.WorldWindow");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
this.saveViewState(worldWindow);
this.saveLayerListState(worldWindow);
}
public void restoreSessionState(WorldWindow worldWindow)
{
if (worldWindow == null)
{
String msg = Logging.getMessage("nullValue.WorldWindow");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
this.restoreViewState(worldWindow);
this.restoreLayerListState(worldWindow);
}
protected void saveViewState(WorldWindow worldWindow)
{
// There's nothing to save if the view is null. We treat this as an exceptional condition rather than a
// supported case and leave the existing state file, if one exists.
View view = worldWindow.getView();
if (view == null)
return;
try
{
// There's nothing to do if the view does not provide restorable state. A null return value from
// getRestorableState is valid, and indicates that the view does not support save/restore. We treat this as
// an exceptional condition rather than a standard case and leave the existing state file, if one exists.
String stateInXml = view.getRestorableState();
if (WWUtil.isEmpty(stateInXml))
return;
// Save the View's restorable state XML to the view state path determined by this SessionState's session key
// and the view state sub-path. This overwrites the contents of an existing state file, if any exists.
WWIO.makeParentDirs(this.getViewStatePath());
WWIO.writeTextFile(stateInXml, new File(this.getViewStatePath()));
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to save view state: " + view, e);
}
}
protected void restoreViewState(WorldWindow worldWindow)
{
// There's nothing to restore if the view is null. We treat this as an exceptional condition rather than a
// supported case and leave the existing state file, if one exists.
View view = worldWindow.getView();
if (view == null)
return;
// There's nothing to restore if the view state file does not exist.
File stateFile = new File(this.getViewStatePath());
if (!stateFile.exists())
return;
try
{
// Read the View's restorable state XML from the view state path determined by this SessionState's session
// key and the view state sub-path.
String stateInXml = WWIO.readTextFile(stateFile);
if (WWUtil.isEmpty(stateInXml))
{
String msg = Logging.getMessage("nullValue.RestorableStateIsNull");
Logging.logger().warning(msg);
return;
}
worldWindow.getView().restoreState(stateInXml);
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to restore view state: " + stateFile, e);
}
}
protected void saveLayerListState(WorldWindow worldWindow)
{
// There's nothing to save if the Model or the LayerList is null. We treat this as an exceptional condition
// rather than a supported case and leave the existing state files, if any exist.
if (worldWindow.getModel() == null || worldWindow.getModel().getLayers() == null)
return;
// Delete the contents of the layer state path directory, but not the directory itself.
File stateFile = new File(this.getLayerStatePath());
try
{
if (stateFile.exists())
WWIO.deleteDirectory(stateFile);
else
stateFile.mkdirs();
int index = 0;
for (Layer layer : worldWindow.getModel().getLayers())
{
if (layer == null)
continue; // There's nothing to save if the Layer is null.
String filename = composeLayerStateFilename(layer.getClass().getName(), index);
this.saveLayerState(layer, new File(stateFile, filename));
index++;
}
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to save layer list state: " + stateFile, e);
}
}
protected void restoreLayerListState(WorldWindow worldWindow)
{
// There's nothing to save if the Model or the LayerList is null. We treat this as an exceptional condition
// rather than a supported case and leave the existing state files, if any exist.
if (worldWindow.getModel() == null || worldWindow.getModel().getLayers() == null)
return;
File stateFile = new File(this.getLayerStatePath());
String[] filenames = stateFile.list();
if (filenames == null || filenames.length == 0)
return;
try
{
Arrays.sort(filenames, LAYER_STATE_FILENAME_COMPARATOR);
LayerList layers = worldWindow.getModel().getLayers();
for (String filename : filenames)
{
Layer layer = this.restoreLayerState(new File(stateFile, filename));
if (layer == null)
continue;
Layer existingLayer = this.findLayer(layers, layer.getName());
if (existingLayer != null)
layers.remove(existingLayer);
LayerStateFilename fn = parseLayerStateFilename(filename);
if (fn != null && fn.index < layers.size())
layers.add(fn.index, layer);
else
layers.add(layer);
}
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to restore layer list state: " + stateFile, e);
}
}
protected void saveLayerState(Layer layer, File stateFile)
{
try
{
// There's nothing to do if the Layer cannot be restored.
if (!this.isLayerRestorable(layer))
return;
// There's nothing to do if the Layer does not provide restorable state. A null return value from
// getRestorableState is valid, and indicates that the Layer does not support save/restore.
String stateInXml = layer.getRestorableState();
if (WWUtil.isEmpty(stateInXml))
return;
// Save the Layer's restorable state XML to the view state path determined by this SessionState's session
// key and the layer state sub-path.
WWIO.writeTextFile(stateInXml, stateFile);
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to save layer state: " + layer, e);
}
}
protected Layer restoreLayerState(File stateFile)
{
try
{
// Read the Layer's restorable state XML from the layer state path determined by this SessionState's session
// key and the layer state sub-path.
String stateInXml = WWIO.readTextFile(stateFile);
if (WWUtil.isEmpty(stateInXml))
{
String msg = Logging.getMessage("nullValue.RestorableStateIsNull");
Logging.logger().warning(msg);
return null;
}
// Get the Layer's class name fom its encoded filename.
LayerStateFilename fn = parseLayerStateFilename(stateFile.getName());
if (fn == null)
{
Logging.logger().warning("Invalid layer state filename: " + stateFile.getName());
return null;
}
// Restore the Layer using a constructor that takes a restorable state XML string as its sole argument.
Class c = Class.forName(fn.className);
Constructor constructor = c.getConstructor(String.class);
Object o = constructor.newInstance(stateInXml);
return (o != null && o instanceof Layer) ? (Layer) o : null;
}
catch (Exception e)
{
Logging.logger().log(Level.SEVERE, "Unable to restore layer state: " + stateFile, e);
return null;
}
}
protected boolean isLayerRestorable(Layer layer)
{
try
{
if (layer.getClass().getConstructor(String.class) != null)
return true;
}
catch (Exception e)
{
// Intentionally left blank. Class.getConstructor throws a NoSuchMethodError if the constructor does not
// exist, in which case the return statement below is executed.
}
return false;
}
protected Layer findLayer(LayerList layers, String layerName)
{
if (layerName == null)
return null;
for (Layer layer : layers)
{
if (layer.getName() != null && layer.getName().equals(layerName))
return layer;
}
return null;
}
protected String getSessionStatePath()
{
String appDataPath = Configuration.getCurrentUserAppDataDirectory();
String sessionDataPath = this.getSessionKey();
// The pattern for storing application data on all unix variants is to put those files in a hidden folder in the
// current user's application data directory. Since the session key is our application data's folder name, we
// ensure that it is hidden by inserting "." character at the beginning of the session key if one does not
// already exist.
if ((Configuration.isLinuxOS() || Configuration.isUnixOS() || Configuration.isSolarisOS())
&& !sessionDataPath.startsWith("."))
{
sessionDataPath = "." + sessionDataPath;
}
return WWIO.appendPathPart(appDataPath, sessionDataPath);
}
protected String getViewStatePath()
{
return WWIO.appendPathPart(this.getSessionStatePath(), VIEW_STATE_PATH);
}
protected String getLayerStatePath()
{
return WWIO.appendPathPart(this.getSessionStatePath(), LAYER_STATE_PATH);
}
protected static LayerStateFilename parseLayerStateFilename(String filename)
{
String filenameWithoutSuffix = WWIO.replaceSuffix(filename, "");
String[] tokens = filenameWithoutSuffix.split(LAYER_STATE_FILENAME_DELIMITER);
if (tokens == null || tokens.length < 2)
return null;
Integer index = WWUtil.makeInteger(tokens[0]);
if (index == null)
return null;
String className = tokens[1].trim();
return new LayerStateFilename(className, index);
}
protected static String composeLayerStateFilename(String className, int index)
{
StringBuilder sb = new StringBuilder();
sb.append(index);
sb.append(LAYER_STATE_FILENAME_DELIMITER);
sb.append(className);
sb.append(".xml");
return sb.toString();
}
}