Java tutorial
/* * Copyright 2014 JBoss 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 io.apiman.manager.ui.client.local.widgets; import io.apiman.manager.ui.client.local.AppMessages; import io.apiman.manager.ui.client.local.beans.JavaScriptFile; import java.util.ArrayList; import java.util.HashSet; import java.util.List; import java.util.Set; import javax.annotation.PostConstruct; import javax.inject.Inject; import org.jboss.errai.ui.client.local.spi.TranslationService; import com.google.gwt.core.client.JavaScriptObject; import com.google.gwt.dom.client.DataTransfer; import com.google.gwt.event.dom.client.DragEnterEvent; import com.google.gwt.event.dom.client.DragEnterHandler; import com.google.gwt.event.dom.client.DragLeaveEvent; import com.google.gwt.event.dom.client.DragLeaveHandler; import com.google.gwt.event.dom.client.DragOverEvent; import com.google.gwt.event.dom.client.DragOverHandler; import com.google.gwt.event.dom.client.DropEvent; import com.google.gwt.event.dom.client.DropHandler; import com.google.gwt.event.logical.shared.ValueChangeEvent; import com.google.gwt.event.logical.shared.ValueChangeHandler; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.user.client.ui.HasValue; import com.google.gwt.user.client.ui.Label; /** * A simple div drop-zone. This allows users to drag and drop files form their * computer onto this widget. * * @author eric.wittmann@redhat.com */ public class DropZone extends Label implements HasValue<List<JavaScriptFile>> { @Inject private TranslationService i18n; private int fileSizeLimit = 1024 * 1024; private Set<String> acceptableTypes = new HashSet<String>(); private List<JavaScriptFile> value = new ArrayList<JavaScriptFile>(); /** * Constructor. */ public DropZone() { } @PostConstruct protected void postConstruct() { addDragEnterHandler(new DragEnterHandler() { @Override public void onDragEnter(DragEnterEvent event) { getElement().addClassName("dropping"); //$NON-NLS-1$ event.preventDefault(); event.stopPropagation(); } }); addDragLeaveHandler(new DragLeaveHandler() { @Override public void onDragLeave(DragLeaveEvent event) { getElement().removeClassName("dropping"); //$NON-NLS-1$ event.preventDefault(); event.stopPropagation(); } }); addDragOverHandler(new DragOverHandler() { @Override public void onDragOver(DragOverEvent event) { if (!getElement().getClassName().contains("dropping")) { //$NON-NLS-1$ getElement().addClassName("dropping"); //$NON-NLS-1$ } event.preventDefault(); event.stopPropagation(); } }); addDropHandler(new DropHandler() { @Override public void onDrop(DropEvent event) { getElement().removeClassName("dropping"); //$NON-NLS-1$ event.preventDefault(); event.stopPropagation(); doDrop(event); } }); } /** * Called when the user drops a file. * * @param event */ protected void doDrop(DropEvent event) { value.clear(); handleFiles(event.getDataTransfer()); getElement().addClassName("dropped"); //$NON-NLS-1$ String text = createDroppedText(); getElement().setInnerText(text); fireValueChangeEvent(); } /** * @return the text to display when files have been dropped */ private String createDroppedText() { StringBuilder builder = new StringBuilder(); builder.append(i18n.format(AppMessages.FILES_DROPPED)); boolean first = true; for (JavaScriptFile javaScriptFile : value) { if (!first) { builder.append(", "); //$NON-NLS-1$ } builder.append(javaScriptFile.getName()); first = false; } return builder.toString(); } /** * Called to handle the list of files that were dropped. * * @param dt */ public final native void handleFiles(DataTransfer dt) /*-{ if (dt && dt.files) { var files = dt.files; for (var i = 0; i < files.length; i++) { var file = files[i]; if (this.@io.apiman.manager.ui.client.local.widgets.DropZone::accept(Ljava/lang/String;ILjava/lang/String;)(file.name, file.size, file.type)) { this.@io.apiman.manager.ui.client.local.widgets.DropZone::addFile(Lcom/google/gwt/core/client/JavaScriptObject;)(file); } } } }-*/; /** * Adds a file to the list of files. * @param jsFile */ protected void addFile(JavaScriptObject jsFile) { value.add(new JavaScriptFile(jsFile)); } /** * Returns true if the drop zone accepts the dropped file. * * @param fileName * @param fileSize * @param fileType */ protected boolean accept(String fileName, int fileSize, String fileType) { return true; } /** * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler) */ @Override public HandlerRegistration addValueChangeHandler(ValueChangeHandler<List<JavaScriptFile>> handler) { return addHandler(handler, ValueChangeEvent.getType()); } /** * @see com.google.gwt.user.client.ui.HasValue#getValue() */ @Override public List<JavaScriptFile> getValue() { return value; } /** * @see com.google.gwt.user.client.ui.HasValue#setValue(java.lang.Object) */ @Override public void setValue(List<JavaScriptFile> value) { setValue(value, false); } /** * @see com.google.gwt.user.client.ui.HasValue#setValue(java.lang.Object, * boolean) */ @Override public void setValue(List<JavaScriptFile> value, boolean fireEvents) { this.value = value; if (fireEvents) { fireValueChangeEvent(); } } /** * Fires the value change event. */ private void fireValueChangeEvent() { ValueChangeEvent.fire(this, value); } }