Java tutorial
/* * Copyright (c) 2012 the original author or authors. * * 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 ca.simplegames.micro.utils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.io.*; /** * Simple utility methods for file and stream copying. * All copy methods use a block size of 4096 bytes, * and close all affected streams when done. * <p/> * <p>Mainly for use within the framework, * but also useful for application code. * * @author Juergen Hoeller * @author <a href="mailto:florin.patrascu@gmail.com">Florin T.PATRASCU</a> * @since 06.10.2003 */ public abstract class IO { private static final Log log = LogFactory.getLog(IO.class); public static final int BUFFER_SIZE = 4096; //--------------------------------------------------------------------- // Copy methods for java.io.File //--------------------------------------------------------------------- /** * Copy the contents of the given input File to the given output File. * * @param in the file to copy from * @param out the file to copy to * @return the number of bytes copied * @throws java.io.IOException in case of I/O errors */ public static long copy(File in, File out) throws IOException { return copy(new BufferedInputStream(new FileInputStream(in)), new BufferedOutputStream(new FileOutputStream(out))); } /** * Copy the contents of the given byte array to the given output File. * * @param in the byte array to copy from * @param out the file to copy to * @throws IOException in case of I/O errors */ public static void copy(byte[] in, File out) throws IOException { ByteArrayInputStream inStream = new ByteArrayInputStream(in); OutputStream outStream = new BufferedOutputStream(new FileOutputStream(out)); copy(inStream, outStream); } /** * Copy the contents of the given input File into a new byte array. * * @param in the file to copy from * @return the new byte array that has been copied to * @throws IOException in case of I/O errors */ public static byte[] copyToByteArray(File in) throws IOException { return copyToByteArray(new BufferedInputStream(new FileInputStream(in))); } //--------------------------------------------------------------------- // Copy methods for java.io.InputStream / java.io.OutputStream //--------------------------------------------------------------------- /** * Copy the contents of the given InputStream to the given OutputStream. * Closes both streams when done. * * @param in the stream to copy from * @param out the stream to copy to * @return the number of bytes copied * @throws IOException in case of I/O errors */ public static long copy(InputStream in, OutputStream out) throws IOException { try { int byteCount = 0; byte[] buffer = new byte[BUFFER_SIZE]; int bytesRead; while ((bytesRead = in.read(buffer)) != -1) { out.write(buffer, 0, bytesRead); byteCount += bytesRead; } out.flush(); return byteCount; } finally { IO.close(in); IO.close(out); } } /** * Copy the contents of the given byte array to the given OutputStream. * Closes the stream when done. * * @param in the byte array to copy from * @param out the OutputStream to copy to * @throws IOException in case of I/O errors */ public static void copy(byte[] in, OutputStream out) throws IOException { try { out.write(in); } finally { try { out.close(); } catch (IOException ex) { log.warn("Could not close OutputStream", ex); } } } /** * Copy the contents of the given InputStream into a new byte array. * Closes the stream when done. * * @param in the stream to copy from * @return the new byte array that has been copied to * @throws IOException in case of I/O errors */ public static byte[] copyToByteArray(InputStream in) throws IOException { ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE); copy(in, out); return out.toByteArray(); } //--------------------------------------------------------------------- // Copy methods for java.io.Reader / java.io.Writer //--------------------------------------------------------------------- /** * Copy the contents of the given Reader to the given Writer. * Closes both when done. * * @param in the Reader to copy from * @param out the Writer to copy to * @return the number of characters copied * @throws IOException in case of I/O errors */ public static int copy(Reader in, Writer out) throws IOException { try { int byteCount = 0; char[] buffer = new char[BUFFER_SIZE]; int bytesRead; while ((bytesRead = in.read(buffer)) != -1) { out.write(buffer, 0, bytesRead); byteCount += bytesRead; } out.flush(); return byteCount; } finally { IO.close(out); IO.close(in); } } /** * Copy the contents of the given Reader into a String. * Closes the reader when done. * * @param in the reader to copy from * @return the String that has been copied to * @throws IOException in case of I/O errors */ public static String copyToString(Reader in) throws IOException { StringWriter out = new StringWriter(); copy(in, out); return out.toString(); } /** * Close the given stream if the stream is not null. * * @param s The stream */ public static void close(InputStream s) { if (s != null) { try { s.close(); } catch (Exception e) { log.error("Error closing stream: " + e.getMessage()); } } } /** * Close the given stream if the stream is not null. * * @param s The stream */ public static void close(Reader s) { if (s != null) { try { s.close(); } catch (Exception e) { log.error("Error closing reader: " + e.getMessage()); } } } /** * Close the given stream if the stream is not null. * * @param s The stream */ public static void close(OutputStream s) { if (s != null) { try { s.close(); } catch (Exception e) { log.error("Error closing stream: " + e.getMessage()); } } } /** * Close the given stream if the stream is not null. * * @param s The stream */ public static void close(Writer s) { if (s != null) { try { s.close(); } catch (Exception e) { log.error("Error closing writer: " + e.getMessage()); } } } /** * Read the data from the given file into a byte array and return * the array. * * @param file The file * @return The byte array * @throws IOException */ public static byte[] readData(File file) throws IOException { BufferedInputStream in = null; ByteArrayOutputStream out = null; try { in = new BufferedInputStream(new FileInputStream(file)); out = new ByteArrayOutputStream(); int c = -1; while ((c = in.read()) != -1) { out.write(c); } return out.toByteArray(); } finally { IO.close(in); IO.close(out); } } /** * Write the byte array to the given file. * * @param file The file to write to * @param data The data array * @throws IOException */ public static void writeData(File file, byte[] data) throws IOException { FileOutputStream out = null; try { out = new FileOutputStream(file); out.write(data); } finally { close(out); } } /** * Read the data from the given reader and return it is a single String. * * @param in The Reader * @return The String * @throws IOException */ public static String getString(Reader in) throws IOException { return copyToString(in); } /** * Read the data from the given InputStream and return it is a single String. * * @param in The InputStream * @return The String * @throws IOException */ public static String getString(InputStream in) throws IOException { return IO.copyToString(new BufferedReader(new InputStreamReader(in))); } public static long copy(String s, OutputStream out) throws IOException { return copy(new StringReader(s), new BufferedWriter(new OutputStreamWriter(out))); } }