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[Jnode-svn-commits] SF.net SVN: jnode:[5366] trunk
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From: <chr...@us...> - 2009-04-29 22:41:01
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Revision: 5366
http://jnode.svn.sourceforge.net/jnode/?rev=5366&view=rev
Author: chrisboertien
Date: 2009-04-29 22:40:55 +0000 (Wed, 29 Apr 2009)
Log Message:
-----------
Added an IOUtils class to org.jnode.command.util
Mostly some convenience methods to make dealing with streams a little easier.
Signed-off-by: chrisboertien <chr...@gm...>
Added Paths:
-----------
trunk/coreutils/
trunk/coreutils/src/
trunk/coreutils/src/commands/
trunk/coreutils/src/commands/org/
trunk/coreutils/src/commands/org/jnode/
trunk/coreutils/src/commands/org/jnode/command/
trunk/coreutils/src/commands/org/jnode/command/util/
trunk/coreutils/src/commands/org/jnode/command/util/IOUtils.java
Added: trunk/coreutils/src/commands/org/jnode/command/util/IOUtils.java
===================================================================
--- trunk/coreutils/src/commands/org/jnode/command/util/IOUtils.java (rev 0)
+++ trunk/coreutils/src/commands/org/jnode/command/util/IOUtils.java 2009-04-29 22:40:55 UTC (rev 5366)
@@ -0,0 +1,418 @@
+/*
+ * $Id$
+ *
+ * Copyright (C) 2003-2009 JNode.org
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; If not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+package org.jnode.command.util;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.Closeable;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.Flushable;
+import java.io.InputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.io.Reader;
+
+/**
+ * Convenience IO methods.
+ *
+ * @author chris boertien
+ */
+public final class IOUtils {
+
+ private static final int BUFFER_SIZE = 4096;
+
+ private static final String ex_null_param = "A required paramater is null";
+
+ /**
+ * Call the close method of a list of Closeable objects.
+ *
+ * This will not throw a NullPointerException if any of the objects are null.
+ *
+ * This is a convenience method that traps the exception from various
+ * stream close() methods.
+ *
+ * @param objs one or more Closeable objects.
+ */
+ public static void close(Closeable... objs) {
+ close(false, objs);
+ }
+
+ /**
+ * Call the close method of a list of Closeable objects.
+ *
+ * If the flush paramater is set to true, and an object implements
+ * the Flushable interface, then the flush method will be called before
+ * the close method is called.
+ *
+ * This will not throw a NullPointerException if any of the objects are null.
+ *
+ * This will not throw an IOException if either the close or flush methods throw
+ * an IOException.
+ *
+ * If calling flush causes an IOException, close will still be called.
+ *
+ * @param flush if true, check if the object is Flushable
+ * @param objs one or more Closeable objects
+ */
+ public static void close(boolean flush, Closeable... objs) {
+ for (Closeable obj : objs) {
+ if (obj != null) {
+ if (flush && (obj instanceof Flushable)) {
+ try {
+ ((Flushable) obj).flush();
+ } catch (IOException _) {
+ // ignore
+ }
+ }
+ try {
+ obj.close();
+ } catch (IOException _) {
+ // ignore
+ }
+ }
+ }
+ }
+
+ /**
+ * Copies data from an Inputstream to an OutputStream.
+ *
+ * This method allocates a 4096 byte buffer each time it is called.
+ *
+ * At the end of writing, the OutputStream will be flushed, but no streams will be closed.
+ *
+ * @param in the stream to read from
+ * @param out the stream to write to
+ * @param bufferSize the size of buffer to use for the copy
+ * @return the number of bytes read from the input stream
+ * @throws NullPointerException if either in or out are null
+ * @throws IOException if an I/O error occurs
+ */
+ public static long copyStream(InputStream in, OutputStream out) throws IOException {
+ return copyStream(in, out, new byte[BUFFER_SIZE]);
+ }
+
+ /**
+ * Copies data from an Inputstream to an OutputStream.
+ *
+ * This method allocates a buffer of 'bufferSize' when it is called.
+ *
+ * At the end of writing, the OutputStream will be flushed, but no streams will be closed.
+ *
+ * @param in the stream to read from
+ * @param out the stream to write to
+ * @param bufferSize the size of buffer to use for the copy
+ * @return the number of bytes read from the input stream
+ * @throws NullPointerException if either in or out are null
+ * @throws IOException if an I/O error occurs
+ */
+ public static long copyStream(InputStream in, OutputStream out, int bufferSize) throws IOException {
+ return copyStream(in, out, new byte[bufferSize]);
+ }
+
+ /**
+ * Copies data from an InputStream to an OutputStream
+ *
+ * If copying multiple streams, this method may be prefered to the others
+ * as a way to use the same buffer instead of allocating a new buffer on each call.
+ *
+ * At the end of writing, the OutputStream will be flushed, but no streams will be closed.
+ *
+ * @param in the stream to read from
+ * @param out the stream to write to
+ * @param buffer a pre-allocated buffer to use.
+ * @return the number of bytes read from the input stream
+ * @throws NullPointerException if either in, out or buffer are null
+ * @throws IOException if an I/O error occurs
+ */
+ public static long copyStream(InputStream in, OutputStream out, byte[] buffer) throws IOException {
+ checkNull(in, out, buffer);
+
+ long totalBytes = 0;
+ int len = 0;
+ while ((len = in.read(buffer)) > 0) {
+ out.write(buffer, 0, len);
+ totalBytes += len;
+ }
+ out.flush();
+ return totalBytes;
+ }
+
+ /**
+ * Opens an InputStream on a file for reading.
+ *
+ * This method will not throw a FileNotFoundException or SecurityException like
+ * the FileInputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @return an InputStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ */
+ public static InputStream openInputStream(File file) {
+ return openInputStream(file, false);
+ }
+
+ /**
+ * Opens an InputStream on a file for reading.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileInputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @param buffer if true, wrap the stream in a buffered stream
+ * @return an InpustStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ */
+ public static InputStream openInputStream(File file, boolean buffer) {
+ return openInputStream(file, buffer, BUFFER_SIZE);
+ }
+
+ /**
+ * Opens an InputStream on a file for reading.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileInputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @param buffer if true, wrap the stream in a buffered stream
+ * @param bufferSize the buffer size to use if buffer is true
+ * @return an InpustStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ * @throws IllegalArgumentException if bufferSize < 0
+ */
+ public static InputStream openInputStream(File file, boolean buffer, int bufferSize) {
+ checkNull(file);
+
+ try {
+ InputStream in = new FileInputStream(file);
+ if (buffer) {
+ in = new BufferedInputStream(in, bufferSize);
+ }
+ return in;
+ } catch (FileNotFoundException e) {
+ return null;
+ } catch (SecurityException e2) {
+ return null;
+ }
+ }
+
+ /**
+ * Opens an OutputStream on a file for writing.
+ *
+ * If the file exists and has content, it will be overwritten. That is to say the append
+ * paramater will be false.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileOutputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @return an OutputStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ */
+ public static OutputStream openOutputStream(File file) {
+ return openOutputStream(file, false, 0);
+ }
+
+ /**
+ * Opens an OutputStream on a file for writing.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileOutputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @param append if true, open the stream in append mode
+ * @return an OutputStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ */
+ public static OutputStream openOutputstream(File file, boolean append) {
+ return openOutputStream(file, append, 0);
+ }
+
+ /**
+ * Opens an OutputStream on a file for writing.
+ *
+ * The stream will be wrapped in a buffered stream if bufferSize is > 0.
+ *
+ * If the file exists and has content, it will be overwritten. That is to say the append
+ * paramater will be false.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileOutputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @param bufferSize if this is > 0, use it as the buffer size for the stream
+ * @return an OutputStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ * @throws IllegalArgumentException if bufferSize < 0
+ */
+ public static OutputStream openOutputStream(File file, int bufferSize) {
+ return openOutputStream(file, false, bufferSize);
+ }
+
+ /**
+ * Opens an OutputStream on a file for writing.
+ *
+ * The stream will be wrapped in a buffered stream if bufferSize is > 0.
+ *
+ * This method will not throw a FileNotFoundException or a SecurityException like
+ * the FileOutputStream constructor would.
+ *
+ * @param file the file to open a stream on
+ * @param bufferSize if this is > 0, use it as the buffer size for the stream
+ * @param append if true, open the stream in append mode
+ * @return an OutputStream on the file, or null if an exception was thrown
+ * @throws NullPointerException if file is null
+ * @throws IllegalArgumentException if bufferSize < 0
+ */
+ public static OutputStream openOutputStream(File file, boolean append, int bufferSize) {
+ checkNull(file);
+
+ try {
+ OutputStream out = new FileOutputStream(file, append);
+
+ if (bufferSize > 0) {
+ out = new BufferedOutputStream(out, bufferSize);
+ }
+ return out;
+ } catch (FileNotFoundException e) {
+ return null;
+ } catch (SecurityException e2) {
+ return null;
+ }
+ }
+
+ /**
+ * Prompt the user with a question, asking for a yes or no response.
+ *
+ * The default response if none is given will be 'yes'
+ *
+ * @param in the reader to read user input from.
+ * @param out the writer to send the prompt to the user
+ * @param str the prompt to send to the user
+ * @return true if the user said yes, false if no
+ */
+ public static boolean promptYesOrNo(Reader in, PrintWriter out, String prompt) {
+ return promptYesOrNo(in, out, prompt, true);
+ }
+
+ /**
+ * Prompt the user with a question, asking for a yes or no response.
+ *
+ * If out is not attached to a terminal, then the user will not see the prompt
+ *
+ * If in is not attached to a terminal, then this method has undefined behavior.
+ *
+ * If the user inputs an answer that does not being with an 'n', 'N', 'y' or 'Y'
+ * then it will prompt the user again. If something causes this loop to execute
+ * indefinetly, it has limited loop iterations. If this loop cap is reached, the
+ * method will return false.
+ *
+ * If the user inputs nothing, then the defaultChoice is used.
+ *
+ * If the Reader is not a BufferedReader, then it will be wrapped in one.
+ *
+ * @param in the reader to read user input from.
+ * @param out the writer to send the prompt to the user
+ * @param str the prompt to send to the user
+ * @param defaultChoice if the user inputs no reply, this value is returned
+ * @return true if the user said yes, false if no
+ * @throws NullPointerException if in, out or str are null
+ */
+ public static boolean promptYesOrNo(Reader in, PrintWriter out, String prompt, boolean defaultChoice) {
+ String input;
+
+ // put a cap on the loops so it doesn't become an infinite loop
+ // this can happen if Reader is not attached to a tty
+ for (int i = 0; i < 10; i++) {
+ input = prompt(in, out, prompt);
+
+ if (input == null) {
+ return false;
+ }
+
+ if (input.length() == 0) {
+ return defaultChoice;
+ }
+
+ switch(input.charAt(0)) {
+ case 'y' :
+ case 'Y' :
+ return true;
+ case 'n' :
+ case 'N' :
+ return false;
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Prompt the user with a question and capture the response.
+ *
+ * If out is not attached to a terminal, then the user will not see the prompt
+ *
+ * If in is not attached to a terminal, then this method has undefined behavior.
+ *
+ * If the Reader is not a BufferedReader, then it will be wrapped in one.
+ *
+ * @param in the reader to read user input from.
+ * @param out the writer to send the prompt to the user
+ * @param str the prompt to send to the user
+ * @return the string captured from the user, or null if an I/O error occurred.
+ * @throws NullPointerException if in, out or str are null
+ */
+ public static String prompt(Reader in, PrintWriter out, String prompt) {
+ checkNull(in, out, prompt);
+
+ String input;
+ BufferedReader reader;
+
+ if (in instanceof BufferedReader) {
+ reader = (BufferedReader) in;
+ } else {
+ reader = new BufferedReader(in);
+ }
+
+ out.print(prompt);
+ try {
+ input = reader.readLine();
+ } catch (IOException e) {
+ return null;
+ } finally {
+ out.println();
+ }
+
+ return input;
+ }
+
+ /**
+ * Check for null objects in a list of objects.
+ */
+ private static void checkNull(Object... objs) {
+ for(Object obj : objs) {
+ if (obj == null) throw new NullPointerException(ex_null_param);
+ }
+ }
+}
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