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.List; import org.apache.commons.fileupload.FileItem; import org.apache.wicket.markup.ComponentTag; import org.apache.wicket.markup.html.form.FormComponent; import org.apache.wicket.model.IModel; import org.apache.wicket.protocol.http.IMultipartWebRequest; import org.apache.wicket.request.Request; import org.apache.wicket.util.convert.ConversionException; import org.apache.wicket.util.string.Strings; /** * Form component that corresponds to a <input type="file">. When a FileInput * component is nested in a {@link org.apache.wicket.markup.html.form.Form}, that has multipart == * true, its model is updated with the {@link org.apache.wicket.markup.html.form.upload.FileUpload} * for this component. * <p> * <strong>NOTE</strong>The model of this component is reset with {@code null} at the end of the * request because {@link FileUpload} instances do not survive across requests since the input * streams they point to will be closed. Because of this, the {@link FileUpload} instance should be * processed within the same request as the form containing it was submitted. * </p> * * @author Eelco Hillenius */ public class FileUploadField extends FormComponent<List<FileUpload>> { private static final long serialVersionUID = 1L; private transient List<FileUpload> fileUploads; /** * @see org.apache.wicket.Component#Component(String) */ public FileUploadField(final String id) { super(id); } /** * @param id * See Component * @param model * the model holding the uploaded {@link FileUpload}s */ @SuppressWarnings("unchecked") public FileUploadField(final String id, IModel<? extends List<FileUpload>> model) { super(id, (IModel<List<FileUpload>>) model); } /** * @return the first uploaded file if HTML5 <input type="file" <strong>multiple</strong> * /> is used and the browser supports <em>multiple</em>, otherwise returns the * single uploaded file. * @see #getFileUploads() */ public FileUpload getFileUpload() { List<FileUpload> fileUploads = getFileUploads(); return fileUploads.isEmpty() ? null : fileUploads.get(0); } /** * @return a list of all uploaded files. The list is empty if no files were selected. It will return more than one files if: * <ul> * <li>HTML5 <input type="file" <strong>multiple</strong> /> is used</li> * <li>the browser supports <em>multiple</em> attribute</li> * <li>the user has selected more than one files from the <em>Select file</em> dialog</li> * </ul> */ public List<FileUpload> getFileUploads() { if (fileUploads != null) { return fileUploads; } fileUploads = new ArrayList<>(); // Get request final Request request = getRequest(); // If we successfully installed a multipart request if (request instanceof IMultipartWebRequest) { // Get the item for the path final List<FileItem> fileItems = ((IMultipartWebRequest) request).getFile(getInputName()); if (fileItems != null) { for (FileItem item : fileItems) { // WICKET-6270 detect empty field by missing file name if (Strings.isEmpty(item.getName()) == false) { fileUploads.add(new FileUpload(item)); } } } } return fileUploads; } @Override public void updateModel() { if (getModel() != null) { super.updateModel(); } } @Override public String[] getInputAsArray() { List<FileUpload> fileUploads = getFileUploads(); if (fileUploads.isEmpty() == false) { List<String> clientFileNames = new ArrayList<>(); for (FileUpload fu : fileUploads) { clientFileNames.add(fu.getClientFileName()); } return clientFileNames.toArray(new String[clientFileNames.size()]); } return null; } @Override protected List<FileUpload> convertValue(String[] value) throws ConversionException { final String[] filenames = getInputAsArray(); if (filenames == null) { return null; } return getFileUploads(); } @Override public boolean isMultiPart() { return true; } @Override protected void onComponentTag(ComponentTag tag) { // Must be attached to an input tag checkComponentTag(tag, "input"); // Check for file type checkComponentTagAttribute(tag, "type", "file"); // Default handling for component tag super.onComponentTag(tag); } /** * Clean up at the end of the request. This means closing all inputstreams which might have been * opened from the fileUpload. * * @see org.apache.wicket.Component#onDetach() */ @Override protected void onDetach() { if (fileUploads != null) { if (forceCloseStreamsOnDetach()) { for (FileUpload fu : fileUploads) { fu.closeStreams(); } if (getModel() != null) { getModel().setObject(null); } } fileUploads = null; } 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; } }