Java tutorial
/** * Copyright 2011 meltmedia * * 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 org.xchain.framework.util; import java.net.Socket; import java.nio.channels.Channel; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.io.IOException; import java.io.Reader; import java.io.Writer; import org.slf4j.Logger; /** * A collection of useful static methods for doing io operation. * * @author Mike Moulton * @author Christian Trimble * @author John Trimble * @author Josh Kennedy */ public class IoUtil { /** * Closes an input stream if it is not null. If an IOException is raised during closing of the stream, it is ignored. * * @param in the input stream to close, or null. */ public static void close(InputStream in, Logger log) { if (in != null) { try { in.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing an input stream.", ioe); } } } } /** * Exists to provide an upgrade path from Commons Logging to SLF4J * @param in * @param log */ @Deprecated public static void close(InputStream in, org.apache.commons.logging.Log log) { if (in != null) { try { in.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing an input stream.", ioe); } } } } /** * Closes an output stream if it is not null. If an IOException is raised during closing of the stream, it is ignored. * * @param out the output stream to close, or null. */ public static void close(OutputStream out, Logger log) { if (out != null) { try { out.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing an output stream.", ioe); } } } } /** * Exists to provide an upgrade path from Commons Logging to SLF4J * * @param out * @param log */ @Deprecated public static void close(OutputStream out, org.apache.commons.logging.Log log) { if (out != null) { try { out.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing an output stream.", ioe); } } } } public static void close(Socket socket, Logger log) { if (socket != null) { try { socket.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a socket.", ioe); } } } } /** * Exists to provide an upgrade path from Commons Logging to SLF4J * * @param socket * @param log */ @Deprecated public static void close(Socket socket, org.apache.commons.logging.Log log) { if (socket != null) { try { socket.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a socket.", ioe); } } } } public static void close(Reader reader, Logger log) { if (reader != null) { try { reader.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a reader.", ioe); } } } } /** * Exists to provide an upgrade path from Commons Logging to SLF4J * * @param reader * @param log */ @Deprecated public static void close(Reader reader, org.apache.commons.logging.Log log) { if (reader != null) { try { reader.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a reader.", ioe); } } } } public static void close(Writer writer, Logger log) { if (writer != null) { try { writer.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a writer.", ioe); } } } } /** * Exists to provide an upgrade path from Commons Logging to SLF4J * * @param writer * @param log */ @Deprecated public static void close(Writer writer, org.apache.commons.logging.Log log) { if (writer != null) { try { writer.close(); } catch (IOException ioe) { if (log != null && log.isDebugEnabled()) { log.debug("An exception was thrown while closing a writer.", ioe); } } } } public static void close(Channel channel, Logger log) { if (channel != null) { try { channel.close(); } catch (Exception e) { log.debug("An exception was thrown while closing a channel.", e); } } } /** * Copies the input stream bytes into the output stream bytes, using the specified * buffer size when transfering the bytes. This method does not close the streams * when it completes. */ public static void copyStream(InputStream in, OutputStream out, int bufferSize) throws IOException { byte[] buffer = new byte[bufferSize]; int read = 0; while ((read = in.read(buffer)) >= 0) { out.write(buffer, 0, read); } } /** * Copies the content of a reader into a writer, using the specified buffer size while * transfering the characters. */ public static void copyStream(Reader reader, Writer writer, int buffer_length) throws IOException { char[] buffer = new char[buffer_length]; for (int read = reader.read(buffer); read > -1; read = reader.read(buffer)) writer.write(buffer, 0, read); } /** * Utility method to perform a file copy from a File to a File * * @param srcFile * @param dstFile * @return */ public static boolean fileCopy(File srcFile, File dstFile, Logger log) { if (srcFile == null || !srcFile.exists() || !srcFile.isFile()) { log.warn("Could not access source file '{}'.", srcFile.getAbsolutePath()); return false; } try { return fileCopy(new FileInputStream(srcFile), dstFile, log); } catch (FileNotFoundException e) { log.warn("Could not create InputStream from '{}'.", srcFile.getAbsolutePath(), e); return false; } } /** * Utility method to perform a file copy from an InputStream to a File * * @param in * @param dstFile * @param log * @return */ public static boolean fileCopy(InputStream in, File dstFile, Logger log) { // Perform a Check if (in == null || dstFile == null) { log.warn("Either InputSteam or Destination File was false."); return false; } try { if (dstFile.createNewFile()) { OutputStream out = new FileOutputStream(dstFile); byte[] buf = new byte[1024]; int len; while ((len = in.read(buf)) > 0) { out.write(buf, 0, len); } in.close(); out.close(); } else { // Could not create file (probably exists already) if (dstFile.exists()) { log.warn("Could not create '{}' since it already exists", dstFile.getAbsolutePath()); return false; } else { log.warn("Error creating new file '{}'.", dstFile.getAbsolutePath()); return false; } } } catch (IOException e) { log.warn("Error copying file to the destination", e); return false; } log.info("Copied data from InputStream to '{}'", dstFile.getAbsolutePath()); return true; } /** * Utility method to return an InputStream from either a File on the system path, or * from the ConextClassLoader to a resource on the Class Path. Prefers Local System * over Class Path. Throws File Not Found Exception if it does not exist in either place. * * @param name * @return * @throws FileNotFoundException */ public static InputStream getFileStream(String name, Logger log) throws FileNotFoundException { File srcFile = new File(name); try { if (srcFile != null && srcFile.exists() && srcFile.isFile()) { log.info("Found '{}' on File System.", name); // Since it is a real file, grab a stream to it and return (Should not be able to throw exception) return new FileInputStream(srcFile); } } catch (FileNotFoundException e) { // We don't care if it's not found on the file system. log.debug("Could not open stream to file '{}'", name); } InputStream stream = Thread.currentThread().getContextClassLoader().getResourceAsStream(name); if (stream != null) { log.info("Resource found from Class Loader '{}'.", name); return stream; } // Can only get here if the File is not found on either the ClassPath or the InputStream throw new FileNotFoundException("Could not find file '" + name + "'"); } }