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.io.File; import java.io.IOException; import java.io.InputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.ArrayList; import java.util.List; import org.apache.commons.fileupload.FileItem; import org.apache.wicket.util.io.IClusterable; import org.apache.wicket.Session; import org.apache.wicket.WicketRuntimeException; import org.apache.wicket.request.cycle.RequestCycle; import org.apache.wicket.util.file.Files; import org.apache.wicket.util.io.IOUtils; import org.apache.wicket.util.lang.Args; import org.apache.wicket.util.string.Strings; /** * Model for file uploads. Objects of this class should not be kept between requests, and should * therefore be marked as <code>transient</code> if they become a property of an IModel. * * @author Jonathan Locke */ public class FileUpload implements IClusterable { private static final long serialVersionUID = 1L; private final FileItem item; private transient List<InputStream> inputStreamsToClose; /** * Constructor * * @param item * The uploaded file item */ public FileUpload(final FileItem item) { Args.notNull(item, "item"); this.item = item; } /** * Close the streams which has been opened when getting the InputStream using * {@link #getInputStream()}. All the input streams are closed at the end of the request. This * is done when the FileUploadField, which is associated with this FileUpload is detached. * <p> * If an exception is thrown when closing the input streams, we ignore it, because the stream * might have been closed already. */ public final void closeStreams() { if (inputStreamsToClose != null) { for (InputStream inputStream : inputStreamsToClose) { IOUtils.closeQuietly(inputStream); } // Reset the list inputStreamsToClose = null; } } /** * Deletes temp file from disk */ public void delete() { item.delete(); } /** * @return Uploaded file as an array of bytes */ public byte[] getBytes() { return item.get(); } /** * Get the MD5 checksum. * * @param algorithm * the digest algorithm, e.g. MD5, SHA-1, SHA-256, SHA-512 * * @return The cryptographic digest of the file */ public byte[] getDigest(String algorithm) { try { Args.notEmpty(algorithm, "algorithm"); MessageDigest digest = java.security.MessageDigest.getInstance(algorithm); if (item.isInMemory()) { digest.update(getBytes()); return digest.digest(); } InputStream in = null; try { in = item.getInputStream(); byte[] buf = new byte[Math.min((int) item.getSize(), 4096 * 10)]; int len; while (-1 != (len = in.read(buf))) { digest.update(buf, 0, len); } return digest.digest(); } catch (IOException ex) { throw new WicketRuntimeException("Error while reading input data for " + algorithm + " checksum", ex); } finally { IOUtils.closeQuietly(in); } } catch (NoSuchAlgorithmException ex) { String error = String.format("Your java runtime does not support digest algorithm [%s]. " + "Please see java.security.MessageDigest.getInstance(\"%s\")", algorithm, algorithm); throw new WicketRuntimeException(error, ex); } } /** * Get the MD5 checksum. * * @return The MD5 checksum of the file */ public byte[] getMD5() { return getDigest("MD5"); } /** * @since 1.2 * @return name of uploaded client side file */ public String getClientFileName() { String name = item.getName(); // when uploading from localhost some browsers will specify the entire path, we strip it // down to just the file name name = Strings.lastPathComponent(name, '/'); name = Strings.lastPathComponent(name, '\\'); return name; } /** * @return Content type for upload */ public String getContentType() { return item.getContentType(); } /** * Get an input stream for the file uploaded. Use this input stream if you can't use * {@link #writeTo(File)} for persisting the uploaded file. This can be if you need to react * upon the content of the file or need to persist it elsewhere, i.e. a database or external * filesystem. * <p> * <b>PLEASE NOTE!</b><br> * The InputStream return will be closed be Wicket at the end of the request. If you need it * across a request you need to hold on to this FileUpload instead. * * @return Input stream with file contents. * @throws IOException */ public InputStream getInputStream() throws IOException { if (inputStreamsToClose == null) { inputStreamsToClose = new ArrayList<InputStream>(); } InputStream is = item.getInputStream(); inputStreamsToClose.add(is); return is; } /** * @return The upload's size */ public long getSize() { return item.getSize(); } /** * Saves this file upload to a given file on the server side. * * @param file * The file * @throws Exception */ public void writeTo(final File file) throws Exception { Files.remove(file); item.write(file); } /** * Convenience method that copies the input stream returned by {@link #getInputStream()} into a * temporary file. * <p> * Only use this if you actually need a {@link File} to work with, in all other cases use * {@link #getInputStream()} or {@link #getBytes()} * * @since 1.2 * * @return temporary file containing the contents of the uploaded file * @throws Exception */ public final File writeToTempFile() throws Exception { String sessionId = Session.exists() ? Session.get().getId() : ""; String tempFileName = sessionId + "_" + RequestCycle.get().getStartTime(); File temp = File.createTempFile(tempFileName, Files.cleanupFilename(item.getFieldName())); writeTo(temp); return temp; } }