2.1/samples/expenses/src/main/java/com/google/gwt/sample/expenses/client/place/AbstractProxyListActivity.java - gwt - Git at Google

 /*
  * Copyright 2010 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.gwt.sample.expenses.client.place;

 import com.google.gwt.activity.shared.Activity;
 import com.google.gwt.event.shared.EventBus;
 import com.google.gwt.event.shared.HandlerRegistration;
 import com.google.gwt.place.shared.Place;
 import com.google.gwt.place.shared.PlaceChangeEvent;
 import com.google.gwt.place.shared.PlaceController;
 import com.google.gwt.requestfactory.shared.EntityProxy;
 import com.google.gwt.requestfactory.shared.EntityProxyChange;
 import com.google.gwt.requestfactory.shared.EntityProxyId;
 import com.google.gwt.requestfactory.shared.Receiver;
 import com.google.gwt.requestfactory.shared.Request;
 import com.google.gwt.requestfactory.shared.WriteOperation;
 import com.google.gwt.sample.expenses.client.place.ProxyPlace.Operation;
 import com.google.gwt.user.cellview.client.AbstractHasData;
 import com.google.gwt.user.client.ui.AcceptsOneWidget;
 import com.google.gwt.view.client.HasData;
 import com.google.gwt.view.client.ProvidesKey;
 import com.google.gwt.view.client.Range;
 import com.google.gwt.view.client.RangeChangeEvent;
 import com.google.gwt.view.client.SelectionChangeEvent;
 import com.google.gwt.view.client.SingleSelectionModel;

 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 /**
  * Abstract activity for displaying a list of {@link EntityProxy}. These
  * activities are not re-usable. Once they are stopped, they cannot be
  * restarted.
  * <p>
  * Subclasses must:
  *
  * <ul>
  * <li>provide a {@link ProxyListView}
  * <li>implement method to request a full count
  * <li>implement method to find a range of entities
  * <li>respond to "show details" commands
  * </ul>
  * <p>
  * Only the properties required by the view will be requested.
  *
  * @param <P> the type of {@link EntityProxy} listed
  */
 public abstract class AbstractProxyListActivity<P extends EntityProxy>
     implements Activity, ProxyListView.Delegate<P> {

   /**
    * This mapping allows us to update individual rows as records change.
    */
   private final Map<EntityProxyId<P>, Integer> idToRow = new HashMap<EntityProxyId<P>, Integer>();
   private final Map<EntityProxyId<P>, P> idToProxy = new HashMap<EntityProxyId<P>, P>();

   private final PlaceController placeController;
   private final SingleSelectionModel<P> selectionModel;
   private final Class<P> proxyClass;

   private HandlerRegistration rangeChangeHandler;
   private ProxyListView<P> view;
   private AcceptsOneWidget display;

   public AbstractProxyListActivity(PlaceController placeController,
       ProxyListView<P> view, Class<P> proxyType) {
     this.view = view;
     this.placeController = placeController;
     this.proxyClass = proxyType;
     view.setDelegate(this);

     final HasData<P> hasData = view.asHasData();
     rangeChangeHandler = hasData.addRangeChangeHandler(new RangeChangeEvent.Handler() {
       public void onRangeChange(RangeChangeEvent event) {
         AbstractProxyListActivity.this.onRangeChanged(hasData);
       }
     });

     // Inherit the view's key provider
     ProvidesKey<P> keyProvider = ((AbstractHasData<P>) hasData).getKeyProvider();
     selectionModel = new SingleSelectionModel<P>(keyProvider);
     hasData.setSelectionModel(selectionModel);

     selectionModel.addSelectionChangeHandler(new SelectionChangeEvent.Handler() {
       public void onSelectionChange(SelectionChangeEvent event) {
         P selectedObject = selectionModel.getSelectedObject();
         if (selectedObject != null) {
           showDetails(selectedObject);
         }
       }
     });
   }

   public void createClicked() {
     placeController.goTo(new ProxyPlace(proxyClass));
   }

   public ProxyListView<P> getView() {
     return view;
   }

   public String mayStop() {
     return null;
   }

   public void onCancel() {
     onStop();
   }

   /**
    * Called by the table as it needs data.
    */
   public void onRangeChanged(HasData<P> listView) {
     final Range range = listView.getVisibleRange();

     final Receiver<List<P>> callback = new Receiver<List<P>>() {
       @Override
       public void onSuccess(List<P> values) {
         if (view == null) {
           // This activity is dead
           return;
         }
         idToRow.clear();
         idToProxy.clear();
         for (int i = 0, row = range.getStart(); i < values.size(); i++, row++) {
           P proxy = values.get(i);
           @SuppressWarnings("unchecked")
           // Why is this cast needed?
           EntityProxyId<P> proxyId = (EntityProxyId<P>) proxy.stableId();
           idToRow.put(proxyId, row);
           idToProxy.put(proxyId, proxy);
         }
         getView().asHasData().setRowData(range.getStart(), values);
         if (display != null) {
           display.setWidget(getView());
         }
       }
     };

     fireRangeRequest(range, callback);
   }

   public void onStop() {
     view.setDelegate(null);
     view = null;
     rangeChangeHandler.removeHandler();
     rangeChangeHandler = null;
   }

   /**
    * Select the given record, or clear the selection if called with null or an
    * id we don't know.
    */
   public void select(EntityProxyId<P> proxyId) {
     /*
      * The selectionModel will not flash if we put it back to the same state it
      * is already in, so we can keep this code simple.
      */

     // Clear the selection
     P selected = selectionModel.getSelectedObject();
     if (selected != null) {
       selectionModel.setSelected(selected, false);
     }

     // Select the new proxy, if it's relevant
     if (proxyId != null) {
       P selectMe = idToProxy.get(proxyId);
       selectionModel.setSelected(selectMe, true);
     }
   }

   public void start(AcceptsOneWidget display, EventBus eventBus) {
     view.setDelegate(this);
     EntityProxyChange.registerForProxyType(eventBus, proxyClass,
         new EntityProxyChange.Handler<P>() {
           public void onProxyChange(EntityProxyChange<P> event) {
             update(event.getWriteOperation(), event.getProxyId());
           }
         });
     eventBus.addHandler(PlaceChangeEvent.TYPE, new PlaceChangeEvent.Handler() {
       public void onPlaceChange(PlaceChangeEvent event) {
         updateSelection(event.getNewPlace());
       }
     });
     this.display = display;
     init();
     updateSelection(placeController.getWhere());
   }

   public void update(WriteOperation writeOperation, EntityProxyId<P> proxyId) {
     switch (writeOperation) {
       case UPDATE:
         update(proxyId);
         break;

       case DELETE:
         init();
         break;

       case PERSIST:
         /*
          * On create, we presume the new record is at the end of the list, so
          * fetch the last page of items.
          */
         getLastPage();
         break;
     }
   }

   protected abstract Request<List<P>> createRangeRequest(Range range);

   protected abstract void fireCountRequest(Receiver<Long> callback);

   /**
    * Called when the user chooses a record to view. This default implementation
    * sends the {@link PlaceController} to an appropriate {@link ProxyPlace}.
    *
    * @param record the chosen record
    */
   protected void showDetails(P record) {
     placeController.goTo(new ProxyPlace(record.stableId(), Operation.DETAILS));
   }

   @SuppressWarnings("unchecked")
   private EntityProxyId<P> cast(ProxyPlace proxyPlace) {
     return (EntityProxyId<P>) proxyPlace.getProxyId();
   }

   private void fireRangeRequest(final Range range,
       final Receiver<List<P>> callback) {
     createRangeRequest(range).with(getView().getPaths()).fire(callback);
   }

   private void getLastPage() {
     fireCountRequest(new Receiver<Long>() {
       @Override
       public void onSuccess(Long response) {
         if (view == null) {
           // This activity is dead
           return;
         }
         HasData<P> table = getView().asHasData();
         int rows = response.intValue();
         table.setRowCount(rows, true);
         if (rows > 0) {
           int pageSize = table.getVisibleRange().getLength();
           int remnant = rows % pageSize;
           if (remnant == 0) {
             table.setVisibleRange(rows - pageSize, pageSize);
           } else {
             table.setVisibleRange(rows - remnant, pageSize);
           }
         }
         onRangeChanged(table);
       }
     });
   }

   private void init() {
     fireCountRequest(new Receiver<Long>() {
       @Override
       public void onSuccess(Long response) {
         if (view == null) {
           // This activity is dead
           return;
         }
         getView().asHasData().setRowCount(response.intValue(), true);
         onRangeChanged(view.asHasData());
       }
     });
   }

   private void update(EntityProxyId<P> proxyId) {
     final Integer row = idToRow.get(proxyId);
     if (row == null) {
       return;
     }
     fireRangeRequest(new Range(row, 1), new Receiver<List<P>>() {
       @Override
       public void onSuccess(List<P> response) {
         getView().asHasData().setRowData(row,
             Collections.singletonList(response.get(0)));
       }
     });
   }

   private void updateSelection(Place newPlace) {
     if (newPlace instanceof ProxyPlace) {
       ProxyPlace proxyPlace = (ProxyPlace) newPlace;
       if (proxyPlace.getOperation() != Operation.CREATE
           && proxyPlace.getProxyClass().equals(proxyClass)) {
         select(cast(proxyPlace));
         return;
       }
     }

     select(null);
   }
 }
	/*
	* Copyright 2010 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may not
	* use this file except in compliance with the License. You may obtain a copy of
	* the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations under
	* the License.
	*/
	package com.google.gwt.sample.expenses.client.place;

	import com.google.gwt.activity.shared.Activity;
	import com.google.gwt.event.shared.EventBus;
	import com.google.gwt.event.shared.HandlerRegistration;
	import com.google.gwt.place.shared.Place;
	import com.google.gwt.place.shared.PlaceChangeEvent;
	import com.google.gwt.place.shared.PlaceController;
	import com.google.gwt.requestfactory.shared.EntityProxy;
	import com.google.gwt.requestfactory.shared.EntityProxyChange;
	import com.google.gwt.requestfactory.shared.EntityProxyId;
	import com.google.gwt.requestfactory.shared.Receiver;
	import com.google.gwt.requestfactory.shared.Request;
	import com.google.gwt.requestfactory.shared.WriteOperation;
	import com.google.gwt.sample.expenses.client.place.ProxyPlace.Operation;
	import com.google.gwt.user.cellview.client.AbstractHasData;
	import com.google.gwt.user.client.ui.AcceptsOneWidget;
	import com.google.gwt.view.client.HasData;
	import com.google.gwt.view.client.ProvidesKey;
	import com.google.gwt.view.client.Range;
	import com.google.gwt.view.client.RangeChangeEvent;
	import com.google.gwt.view.client.SelectionChangeEvent;
	import com.google.gwt.view.client.SingleSelectionModel;

	import java.util.Collections;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;

	/**
	* Abstract activity for displaying a list of {@link EntityProxy}. These
	* activities are not re-usable. Once they are stopped, they cannot be
	* restarted.
	* <p>
	* Subclasses must:
	*
	* <ul>
	* <li>provide a {@link ProxyListView}
	* <li>implement method to request a full count
	* <li>implement method to find a range of entities
	* <li>respond to "show details" commands
	* </ul>
	* <p>
	* Only the properties required by the view will be requested.
	*
	* @param <P> the type of {@link EntityProxy} listed
	*/
	public abstract class AbstractProxyListActivity<P extends EntityProxy>
	implements Activity, ProxyListView.Delegate<P> {

	/**
	* This mapping allows us to update individual rows as records change.
	*/
	private final Map<EntityProxyId<P>, Integer> idToRow = new HashMap<EntityProxyId<P>, Integer>();
	private final Map<EntityProxyId<P>, P> idToProxy = new HashMap<EntityProxyId<P>, P>();

	private final PlaceController placeController;
	private final SingleSelectionModel<P> selectionModel;
	private final Class<P> proxyClass;

	private HandlerRegistration rangeChangeHandler;
	private ProxyListView<P> view;
	private AcceptsOneWidget display;

	public AbstractProxyListActivity(PlaceController placeController,
	ProxyListView<P> view, Class<P> proxyType) {
	this.view = view;
	this.placeController = placeController;
	this.proxyClass = proxyType;
	view.setDelegate(this);

	final HasData<P> hasData = view.asHasData();
	rangeChangeHandler = hasData.addRangeChangeHandler(new RangeChangeEvent.Handler() {
	public void onRangeChange(RangeChangeEvent event) {
	AbstractProxyListActivity.this.onRangeChanged(hasData);
	}
	});

	// Inherit the view's key provider
	ProvidesKey<P> keyProvider = ((AbstractHasData<P>) hasData).getKeyProvider();
	selectionModel = new SingleSelectionModel<P>(keyProvider);
	hasData.setSelectionModel(selectionModel);

	selectionModel.addSelectionChangeHandler(new SelectionChangeEvent.Handler() {
	public void onSelectionChange(SelectionChangeEvent event) {
	P selectedObject = selectionModel.getSelectedObject();
	if (selectedObject != null) {
	showDetails(selectedObject);
	}
	}
	});
	}

	public void createClicked() {
	placeController.goTo(new ProxyPlace(proxyClass));
	}

	public ProxyListView<P> getView() {
	return view;
	}

	public String mayStop() {
	return null;
	}

	public void onCancel() {
	onStop();
	}

	/**
	* Called by the table as it needs data.
	*/
	public void onRangeChanged(HasData<P> listView) {
	final Range range = listView.getVisibleRange();

	final Receiver<List<P>> callback = new Receiver<List<P>>() {
	@Override
	public void onSuccess(List<P> values) {
	if (view == null) {
	// This activity is dead
	return;
	}
	idToRow.clear();
	idToProxy.clear();
	for (int i = 0, row = range.getStart(); i < values.size(); i++, row++) {
	P proxy = values.get(i);
	@SuppressWarnings("unchecked")
	// Why is this cast needed?
	EntityProxyId<P> proxyId = (EntityProxyId<P>) proxy.stableId();
	idToRow.put(proxyId, row);
	idToProxy.put(proxyId, proxy);
	}
	getView().asHasData().setRowData(range.getStart(), values);
	if (display != null) {
	display.setWidget(getView());
	}
	}
	};

	fireRangeRequest(range, callback);
	}

	public void onStop() {
	view.setDelegate(null);
	view = null;
	rangeChangeHandler.removeHandler();
	rangeChangeHandler = null;
	}

	/**
	* Select the given record, or clear the selection if called with null or an
	* id we don't know.
	*/
	public void select(EntityProxyId<P> proxyId) {
	/*
	* The selectionModel will not flash if we put it back to the same state it
	* is already in, so we can keep this code simple.
	*/

	// Clear the selection
	P selected = selectionModel.getSelectedObject();
	if (selected != null) {
	selectionModel.setSelected(selected, false);
	}

	// Select the new proxy, if it's relevant
	if (proxyId != null) {
	P selectMe = idToProxy.get(proxyId);
	selectionModel.setSelected(selectMe, true);
	}
	}

	public void start(AcceptsOneWidget display, EventBus eventBus) {
	view.setDelegate(this);
	EntityProxyChange.registerForProxyType(eventBus, proxyClass,
	new EntityProxyChange.Handler<P>() {
	public void onProxyChange(EntityProxyChange<P> event) {
	update(event.getWriteOperation(), event.getProxyId());
	}
	});
	eventBus.addHandler(PlaceChangeEvent.TYPE, new PlaceChangeEvent.Handler() {
	public void onPlaceChange(PlaceChangeEvent event) {
	updateSelection(event.getNewPlace());
	}
	});
	this.display = display;
	init();
	updateSelection(placeController.getWhere());
	}

	public void update(WriteOperation writeOperation, EntityProxyId<P> proxyId) {
	switch (writeOperation) {
	case UPDATE:
	update(proxyId);
	break;

	case DELETE:
	init();
	break;

	case PERSIST:
	/*
	* On create, we presume the new record is at the end of the list, so
	* fetch the last page of items.
	*/
	getLastPage();
	break;
	}
	}

	protected abstract Request<List<P>> createRangeRequest(Range range);

	protected abstract void fireCountRequest(Receiver<Long> callback);

	/**
	* Called when the user chooses a record to view. This default implementation
	* sends the {@link PlaceController} to an appropriate {@link ProxyPlace}.
	*
	* @param record the chosen record
	*/
	protected void showDetails(P record) {
	placeController.goTo(new ProxyPlace(record.stableId(), Operation.DETAILS));
	}

	@SuppressWarnings("unchecked")
	private EntityProxyId<P> cast(ProxyPlace proxyPlace) {
	return (EntityProxyId<P>) proxyPlace.getProxyId();
	}

	private void fireRangeRequest(final Range range,
	final Receiver<List<P>> callback) {
	createRangeRequest(range).with(getView().getPaths()).fire(callback);
	}

	private void getLastPage() {
	fireCountRequest(new Receiver<Long>() {
	@Override
	public void onSuccess(Long response) {
	if (view == null) {
	// This activity is dead
	return;
	}
	HasData<P> table = getView().asHasData();
	int rows = response.intValue();
	table.setRowCount(rows, true);
	if (rows > 0) {
	int pageSize = table.getVisibleRange().getLength();
	int remnant = rows % pageSize;
	if (remnant == 0) {
	table.setVisibleRange(rows - pageSize, pageSize);
	} else {
	table.setVisibleRange(rows - remnant, pageSize);
	}
	}
	onRangeChanged(table);
	}
	});
	}

	private void init() {
	fireCountRequest(new Receiver<Long>() {
	@Override
	public void onSuccess(Long response) {
	if (view == null) {
	// This activity is dead
	return;
	}
	getView().asHasData().setRowCount(response.intValue(), true);
	onRangeChanged(view.asHasData());
	}
	});
	}

	private void update(EntityProxyId<P> proxyId) {
	final Integer row = idToRow.get(proxyId);
	if (row == null) {
	return;
	}
	fireRangeRequest(new Range(row, 1), new Receiver<List<P>>() {
	@Override
	public void onSuccess(List<P> response) {
	getView().asHasData().setRowData(row,
	Collections.singletonList(response.get(0)));
	}
	});
	}

	private void updateSelection(Place newPlace) {
	if (newPlace instanceof ProxyPlace) {
	ProxyPlace proxyPlace = (ProxyPlace) newPlace;
	if (proxyPlace.getOperation() != Operation.CREATE
	&& proxyPlace.getProxyClass().equals(proxyClass)) {
	select(cast(proxyPlace));
	return;
	}
	}

	select(null);
	}
	}