Java tutorial
/* * Copyright 2000-2018 Vaadin Ltd. * * 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.vaadin.client.communication; import java.io.Serializable; import java.util.HashSet; import java.util.Set; import com.google.gwt.core.client.JavaScriptObject; import com.google.gwt.event.shared.EventHandler; import com.vaadin.client.FastStringSet; import com.vaadin.client.JsArrayObject; import com.vaadin.client.Profiler; import com.vaadin.client.ServerConnector; import com.vaadin.client.Util; import com.vaadin.client.communication.StateChangeEvent.StateChangeHandler; import com.vaadin.client.metadata.NoDataException; import com.vaadin.client.metadata.Property; import com.vaadin.client.ui.AbstractConnector; import elemental.json.JsonObject; public class StateChangeEvent extends AbstractServerConnectorEvent<StateChangeHandler> { /** * Type of this event, used by the event bus. */ public static final Type<StateChangeHandler> TYPE = new Type<>(); /** * Used to cache a FastStringSet representation of the properties that have * changed if one is needed. */ @Deprecated private FastStringSet changedProperties; /** * Used to cache a Set representation of the changedProperties if one is * needed. */ @Deprecated private Set<String> changedPropertiesSet; private boolean initialStateChange = false; private JsonObject stateJson; @Override public Type<StateChangeHandler> getAssociatedType() { return TYPE; } /** * Creates a new state change event. * * @param connector * the event whose state has changed * @param changedPropertiesSet * a set of names of the changed properties * @deprecated As of 7.0.1, use * {@link #StateChangeEvent(ServerConnector, JsonObject, boolean)} * instead for improved performance. */ @Deprecated public StateChangeEvent(ServerConnector connector, Set<String> changedPropertiesSet) { setConnector(connector); // Keep instance around for caching this.changedPropertiesSet = changedPropertiesSet; changedProperties = FastStringSet.create(); for (String property : changedPropertiesSet) { changedProperties.add(property); } } /** * Creates a new state change event. * * @param connector * the event whose state has changed * @param changedProperties * a set of names of the changed properties * @deprecated As of 7.0.2, use * {@link #StateChangeEvent(ServerConnector, JsonObject, boolean)} * instead for improved performance. */ @Deprecated public StateChangeEvent(ServerConnector connector, FastStringSet changedProperties) { setConnector(connector); this.changedProperties = changedProperties; } /** * /** Creates a new state change event. * * @param connector * the event whose state has changed * @param stateJson * the JSON representation of the state change * @param initialStateChange * <code>true</code> if the state change is for a new connector, * otherwise <code>false</code> */ public StateChangeEvent(ServerConnector connector, JsonObject stateJson, boolean initialStateChange) { setConnector(connector); this.stateJson = stateJson; this.initialStateChange = initialStateChange; } @Override public void dispatch(StateChangeHandler listener) { listener.onStateChanged(this); } /** * Event handler that gets notified whenever any part of the state has been * updated by the server. * * @author Vaadin Ltd * @since 7.0.0 */ public interface StateChangeHandler extends Serializable, EventHandler { /** * Notifies the event handler that the state has changed. * * @param stateChangeEvent * the state change event with details about the change */ public void onStateChanged(StateChangeEvent stateChangeEvent); } /** * Gets the properties that have changed. * * @return a set of names of the changed properties * * @deprecated As of 7.0.1, use {@link #hasPropertyChanged(String)} instead * for improved performance. */ @Deprecated public Set<String> getChangedProperties() { if (changedPropertiesSet == null) { Profiler.enter("StateChangeEvent.getChangedProperties populate"); changedPropertiesSet = new HashSet<>(); getChangedPropertiesFastSet().addAllTo(changedPropertiesSet); Profiler.leave("StateChangeEvent.getChangedProperties populate"); } return changedPropertiesSet; } /** * Gets the properties that have changed. * * @return a set of names of the changed properties * * @deprecated As of 7.0.1, use {@link #hasPropertyChanged(String)} instead * for improved performance. */ @Deprecated public FastStringSet getChangedPropertiesFastSet() { if (changedProperties == null) { Profiler.enter("StateChangeEvent.getChangedPropertiesFastSet populate"); changedProperties = FastStringSet.create(); addJsonFields(stateJson, changedProperties, ""); if (isInitialStateChange()) { addAllStateFields(AbstractConnector.getStateType(getConnector()), changedProperties, ""); } Profiler.leave("StateChangeEvent.getChangedPropertiesFastSet populate"); } return changedProperties; } /** * Checks whether the give property has changed. * * @param property * the name of the property to check * @return <code>true</code> if the property has changed, else * <code>false></code> */ public boolean hasPropertyChanged(String property) { if (isInitialStateChange()) { // Everything has changed for a new connector return true; } else if (stateJson != null) { // Check whether it's in the json object return isInJson(property, Util.json2jso(stateJson)); } else { // Legacy cases if (changedProperties != null) { // Check legacy stuff return changedProperties.contains(property); } else if (changedPropertiesSet != null) { // Check legacy stuff return changedPropertiesSet.contains(property); } else { throw new IllegalStateException( "StateChangeEvent should have either stateJson, changedProperties or changePropertiesSet"); } } } /** * Checks whether the given property name (which might contains dots) is * defined in some JavaScript object. * * @param property * the name of the property, might include dots to reference * inner objects * @param target * the JavaScript object to check * @return true if the property is defined */ private static final native boolean isInJson(String property, JavaScriptObject target) /*-{ var segments = property.split('.'); while (typeof target == 'object') { var nextSegment = segments.shift(); if (!(nextSegment in target)) { // Abort if segment is not found return false; } else if (segments.length == 0) { // Done if there are no more segments return true; } else { // Else just go deeper target = target[nextSegment]; } } // Not defined if we reach something that isn't an object return false; }-*/; /** * Recursively adds the names of all properties in the provided state type. * * @param type * the type to process * @param changedProperties * a set of all currently added properties * @param context * the base name of the current object */ @Deprecated private static void addAllStateFields(com.vaadin.client.metadata.Type type, FastStringSet changedProperties, String context) { try { JsArrayObject<Property> properties = type.getPropertiesAsArray(); int size = properties.size(); for (int i = 0; i < size; i++) { Property property = properties.get(i); String propertyName = context + property.getName(); changedProperties.add(propertyName); com.vaadin.client.metadata.Type propertyType = property.getType(); if (propertyType.hasProperties()) { addAllStateFields(propertyType, changedProperties, propertyName + "."); } } } catch (NoDataException e) { throw new IllegalStateException( "No property info for " + type + ". Did you remember to compile the right widgetset?", e); } } /** * Recursively adds the names of all fields in all objects in the provided * json object. * * @param json * the json object to process * @param changedProperties * a set of all currently added fields * @param context * the base name of the current object */ @Deprecated private static void addJsonFields(JsonObject json, FastStringSet changedProperties, String context) { for (String key : json.keys()) { String fieldName = context + key; changedProperties.add(fieldName); JsonObject object = json.get(key); if (object != null) { addJsonFields(object, changedProperties, fieldName + "."); } } } /** * Checks if the state change event is the first one for the given * connector. * * @since 7.1 * @return true if this is the first state change event for the connector, * false otherwise */ public boolean isInitialStateChange() { return initialStateChange; } }