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 au.gov.ansto.bragg.nbi.restlet.fileupload.util; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import org.apache.commons.io.IOUtils; import au.gov.ansto.bragg.nbi.restlet.fileupload.InvalidFileNameException; /** * Utility class for working with streams. * * @version $Id: Streams.java 1565332 2014-02-06 16:42:19Z ggregory $ */ public final class Streams { /** * Private constructor, to prevent instantiation. * This class has only static methods. */ private Streams() { // Does nothing } /** * Default buffer size for use in * {@link #copy(InputStream, OutputStream, boolean)}. */ private static final int DEFAULT_BUFFER_SIZE = 8192; /** * Copies the contents of the given {@link InputStream} * to the given {@link OutputStream}. Shortcut for * <pre> * copy(pInputStream, pOutputStream, new byte[8192]); * </pre> * * @param inputStream The input stream, which is being read. * It is guaranteed, that {@link InputStream#close()} is called * on the stream. * @param outputStream The output stream, to which data should * be written. May be null, in which case the input streams * contents are simply discarded. * @param closeOutputStream True guarantees, that {@link OutputStream#close()} * is called on the stream. False indicates, that only * {@link OutputStream#flush()} should be called finally. * * @return Number of bytes, which have been copied. * @throws IOException An I/O error occurred. */ public static long copy(InputStream inputStream, OutputStream outputStream, boolean closeOutputStream) throws IOException { return copy(inputStream, outputStream, closeOutputStream, new byte[DEFAULT_BUFFER_SIZE]); } /** * Copies the contents of the given {@link InputStream} * to the given {@link OutputStream}. * * @param inputStream The input stream, which is being read. * It is guaranteed, that {@link InputStream#close()} is called * on the stream. * @param outputStream The output stream, to which data should * be written. May be null, in which case the input streams * contents are simply discarded. * @param closeOutputStream True guarantees, that {@link OutputStream#close()} * is called on the stream. False indicates, that only * {@link OutputStream#flush()} should be called finally. * @param buffer Temporary buffer, which is to be used for * copying data. * @return Number of bytes, which have been copied. * @throws IOException An I/O error occurred. */ public static long copy(InputStream inputStream, OutputStream outputStream, boolean closeOutputStream, byte[] buffer) throws IOException { OutputStream out = outputStream; InputStream in = inputStream; try { long total = 0; for (;;) { int res = in.read(buffer); if (res == -1) { break; } if (res > 0) { total += res; if (out != null) { out.write(buffer, 0, res); } } } if (out != null) { if (closeOutputStream) { out.close(); } else { out.flush(); } out = null; } in.close(); in = null; return total; } finally { IOUtils.closeQuietly(in); if (closeOutputStream) { IOUtils.closeQuietly(out); } } } /** * This convenience method allows to read a * {@link org.apache.commons.fileupload.FileItemStream}'s * content into a string. The platform's default character encoding * is used for converting bytes into characters. * * @param inputStream The input stream to read. * @see #asString(InputStream, String) * @return The streams contents, as a string. * @throws IOException An I/O error occurred. */ public static String asString(InputStream inputStream) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); copy(inputStream, baos, true); return baos.toString(); } /** * This convenience method allows to read a * {@link org.apache.commons.fileupload.FileItemStream}'s * content into a string, using the given character encoding. * * @param inputStream The input stream to read. * @param encoding The character encoding, typically "UTF-8". * @see #asString(InputStream) * @return The streams contents, as a string. * @throws IOException An I/O error occurred. */ public static String asString(InputStream inputStream, String encoding) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); copy(inputStream, baos, true); return baos.toString(encoding); } /** * Checks, whether the given file name is valid in the sense, * that it doesn't contain any NUL characters. If the file name * is valid, it will be returned without any modifications. Otherwise, * an {@link InvalidFileNameException} is raised. * * @param fileName The file name to check * @return Unmodified file name, if valid. * @throws InvalidFileNameException The file name was found to be invalid. */ public static String checkFileName(String fileName) { if (fileName != null && fileName.indexOf('\u0000') != -1) { // pFileName.replace("\u0000", "\\0") final StringBuilder sb = new StringBuilder(); for (int i = 0; i < fileName.length(); i++) { char c = fileName.charAt(i); switch (c) { case 0: sb.append("\\0"); break; default: sb.append(c); break; } } throw new InvalidFileNameException(fileName, "Invalid file name: " + sb); } return fileName; } }