Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 org.apache.wicket.markup.html.form.upload; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import org.apache.commons.fileupload.FileItem; import org.apache.wicket.markup.ComponentTag; import org.apache.wicket.markup.head.IHeaderResponse; import org.apache.wicket.markup.head.JavaScriptHeaderItem; import org.apache.wicket.markup.head.OnDomReadyHeaderItem; import org.apache.wicket.markup.html.WebComponent; import org.apache.wicket.markup.html.WebMarkupContainer; import org.apache.wicket.markup.html.basic.Label; import org.apache.wicket.markup.html.form.Form; import org.apache.wicket.markup.html.form.FormComponent; import org.apache.wicket.markup.html.form.FormComponentPanel; import org.apache.wicket.model.IModel; import org.apache.wicket.model.Model; import org.apache.wicket.protocol.http.IMultipartWebRequest; import org.apache.wicket.request.Request; import org.apache.wicket.request.resource.JavaScriptResourceReference; import org.apache.wicket.request.resource.ResourceReference; import org.apache.wicket.util.convert.ConversionException; import org.apache.wicket.util.string.Strings; /** * Form component that allows the user to select multiple files to upload via a single <input * type="file"/> field. * * Notice that this component clears its model at the end of the request, so the uploaded files MUST * be processed within the request they were uploaded. * * Uses javascript implementation from * http://the-stickman.com/web-development/javascript/upload-multiple-files-with-a-single-file-element/ * * For customizing caption text see {@link #RESOURCE_LIMITED} and {@link #RESOURCE_UNLIMITED} * * For an example of styling using CSS see the upload example in wicket-examples * * @author Igor Vaynberg (ivaynberg) */ public class MultiFileUploadField extends FormComponentPanel<Collection<FileUpload>> { private static final long serialVersionUID = 1L; /** * Represents an unlimited max count of uploads */ public static final int UNLIMITED = -1; /** * Resource key used to retrieve caption message for when a limit on the number of uploads is * specified. The limit is represented via ${max} variable. * * Example: org.apache.wicket.mfu.caption.limited=Files (maximum ${max}): */ public static final String RESOURCE_LIMITED = "org.apache.wicket.mfu.caption.limited"; /** * Resource key used to retrieve caption message for when no limit on the number of uploads is * specified. * * Example: org.apache.wicket.mfu.caption.unlimited=Files: */ public static final String RESOURCE_UNLIMITED = "org.apache.wicket.mfu.caption.unlimited"; private static final String NAME_ATTR = "name"; public static final String MAGIC_SEPARATOR = "_mf_"; public static final ResourceReference JS = new JavaScriptResourceReference(MultiFileUploadField.class, "MultiFileUploadField.js"); private final WebComponent upload; private final WebMarkupContainer container; private final int max; private final boolean useMultipleAttr; private transient String[] inputArrayCache = null; /** * Constructor * * @param id */ public MultiFileUploadField(String id) { this(id, null, UNLIMITED); } /** * Constructor * * @param id * @param max * max number of files a user can upload */ public MultiFileUploadField(String id, int max) { this(id, null, max); } /** * Constructor * * @param id * @param model */ public MultiFileUploadField(String id, IModel<? extends Collection<FileUpload>> model) { this(id, model, UNLIMITED); } /** * Constructor * * @param id * @param model * @param max * max number of files a user can upload */ public MultiFileUploadField(String id, IModel<? extends Collection<FileUpload>> model, int max) { this(id, model, max, false); } /** * Constructor * * @param id * @param model * @param max * max number of files a user can upload * @param useMultipleAttr * true in order to use the new HTML5 "multiple" <input> attribute. It will allow * the users to select multiple files at once for multiple times if the browser * supports it, otherwise it will work just as before - one file multiple times. * */ @SuppressWarnings("unchecked") public MultiFileUploadField(String id, IModel<? extends Collection<FileUpload>> model, int max, boolean useMultipleAttr) { super(id, (IModel<Collection<FileUpload>>) model); this.max = max; this.useMultipleAttr = useMultipleAttr; upload = new WebComponent("upload") { @Override protected void onComponentTag(ComponentTag tag) { super.onComponentTag(tag); if (!isEnabledInHierarchy()) { onDisabled(tag); } } }; upload.setOutputMarkupId(true); add(upload); container = new WebMarkupContainer("container"); container.setOutputMarkupId(true); add(container); container.add(new Label("caption", new CaptionModel())); } /** * @see org.apache.wicket.markup.html.form.FormComponentPanel#onComponentTag(org.apache.wicket.markup.ComponentTag) */ @Override protected void onComponentTag(ComponentTag tag) { super.onComponentTag(tag); // remove the name attribute added by the FormComponent if (tag.getAttributes().containsKey(NAME_ATTR)) { tag.getAttributes().remove(NAME_ATTR); } } /** * @see org.apache.wicket.Component#onBeforeRender() */ @Override protected void onBeforeRender() { super.onBeforeRender(); Form<?> form = findParent(Form.class); if (form == null) { // woops throw new IllegalStateException("Component " + getClass().getName() + " must have a " + Form.class.getName() + " component above in the hierarchy"); } } @Override public boolean isMultiPart() { return true; } @Override public void renderHead(IHeaderResponse response) { // initialize the javascript library response.render(JavaScriptHeaderItem.forReference(JS)); response.render(OnDomReadyHeaderItem.forScript( "new MultiSelector('" + getInputName() + "', document.getElementById('" + container.getMarkupId() + "'), " + max + ", " + useMultipleAttr + ", '" + getString("org.apache.wicket.mfu.delete") + "').addElement(document.getElementById('" + upload.getMarkupId() + "'));")); } /** * @see org.apache.wicket.markup.html.form.FormComponent#getInputAsArray() */ @Override public String[] getInputAsArray() { // fake the input array as if it contained an array of all uploaded file // names if (inputArrayCache == null) { // this array will aggregate all input names ArrayList<String> names = null; final Request request = getRequest(); if (request instanceof IMultipartWebRequest) { // retrieve the filename->FileItem map from request final Map<String, List<FileItem>> itemNameToItem = ((IMultipartWebRequest) request).getFiles(); for (Entry<String, List<FileItem>> entry : itemNameToItem.entrySet()) { // iterate over the map and build the list of filenames final String name = entry.getKey(); final List<FileItem> fileItems = entry.getValue(); if (!Strings.isEmpty(name) && name.startsWith(getInputName() + MAGIC_SEPARATOR) && !fileItems.isEmpty() && !Strings.isEmpty(fileItems.get(0).getName())) { // make sure the fileitem belongs to this component and // is not empty names = (names != null) ? names : new ArrayList<String>(); names.add(name); } } } if (names != null) { inputArrayCache = names.toArray(new String[names.size()]); } } return inputArrayCache; } @Override protected Collection<FileUpload> convertValue(String[] value) throws ConversionException { // convert the array of filenames into a collection of FileItems Collection<FileUpload> uploads = null; final String[] filenames = getInputAsArray(); if (filenames != null) { final IMultipartWebRequest request = (IMultipartWebRequest) getRequest(); uploads = new ArrayList<>(filenames.length); for (String filename : filenames) { List<FileItem> fileItems = request.getFile(filename); for (FileItem fileItem : fileItems) { uploads.add(new FileUpload(fileItem)); } } } return uploads; } /** * See {@link FormComponent#updateCollectionModel(FormComponent)} for details on how the model * is updated. */ @Override public void updateModel() { FormComponent.updateCollectionModel(this); } @Override protected void onDetach() { if (forceCloseStreamsOnDetach()) { // cleanup any opened filestreams Collection<FileUpload> uploads = getConvertedInput(); if (uploads != null) { for (FileUpload upload : uploads) { upload.closeStreams(); } } // cleanup any caches inputArrayCache = null; // clean up the model because we don't want FileUpload objects in session Collection<FileUpload> modelObject = getModelObject(); if (modelObject != null) { modelObject.clear(); } } super.onDetach(); } /** * The FileUploadField will close any input streams you have opened in its FileUpload by * default. If you wish to manage the stream yourself (e.g. you want to use it in another * thread) then you can override this method to prevent this behavior. * * @return <code>true</code> if stream should be closed at the end of request */ protected boolean forceCloseStreamsOnDetach() { return true; } /** * Model that will construct the caption string * * @author ivaynberg */ private class CaptionModel implements IModel<String> { private static final long serialVersionUID = 1L; @Override public String getObject() { if (max == UNLIMITED) { return getString(RESOURCE_UNLIMITED); } else { HashMap<String, Object> vars = new HashMap<>(1); vars.put("max", max); return getString(RESOURCE_LIMITED, new Model<>(vars)); } } } }