ioutils.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * 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.util.io;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;


/**
 * General IO Stream manipulation.
 * <p>
 * This class provides static utility methods for input/output operations.
 * <ul>
 * <li>closeQuietly - these methods close a stream ignoring nulls and exceptions
 * <li>toXxx - these methods read data from a stream
 * <li>write - these methods write data to a stream
 * <li>copy - these methods copy all the data from one stream to another
 * <li>contentEquals - these methods compare the content of two streams
 * </ul>
 * <p>
 * The byte-to-char methods and char-to-byte methods involve a conversion step. Two methods are
 * provided in each case, one that uses the platform default encoding and the other which allows you
 * to specify an encoding. You are encouraged to always specify an encoding because relying on the
 * platform default can lead to unexpected results, for example when moving from development to
 * production.
 * <p>
 * All the methods in this class that read a stream are buffered internally. This means that there
 * is no cause to use a <code>BufferedInputStream</code> or <code>BufferedReader</code>. The
 * default buffer size of 4K has been show to be efficient in tests.
 * <p>
 * Wherever possible, the methods in this class do <em>not</em> flush or close the stream. This is
 * to avoid making non-portable assumptions about the streams' origin and further use. Thus the
 * caller is still responsible for closing streams after use.
 * <p>
 * Origin of code: Apache Avalon (Excalibur)
 * 
 * @author Peter Donald
 * @author Jeff Turner
 * @author Matthew Hawthorne
 * @author Stephen Colebourne
 * @author Gareth Davis
 * @version CVS $Revision$ $Date$
 */
public final class IOUtils
{
	// NOTE: This class is focused on InputStream, OutputStream, Reader and
	// Writer. Each method should take at least one of these as a parameter.
	// NOTE: This class should not depend on any other classes

	/**
	 * The default buffer size to use.
	 */
	private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

	/**
	 * Instances should NOT be constructed in standard programming.
	 */
	public IOUtils()
	{
	}

	// -----------------------------------------------------------------------
	/**
	 * Unconditionally close an <code>Reader</code>.
	 * <p>
	 * Equivalent to {@link Reader#close()}, except any exceptions will be ignored. This is
	 * typically used in finally blocks.
	 * 
	 * @param input
	 *            the Reader to close, may be null or already closed
	 */
	public static void closeQuietly(Reader input)
	{
		if (input != null)
		{
			try
			{
				input.close();
			}
			catch (Exception e)
			{
				// ignore
			}
		}
	}

	/**
	 * Unconditionally close a <code>Writer</code>.
	 * <p>
	 * Equivalent to {@link Writer#close()}, except any exceptions will be ignored. This is
	 * typically used in finally blocks.
	 * 
	 * @param output
	 *            the Writer to close, may be null or already closed
	 */
	public static void closeQuietly(Writer output)
	{
		if (output != null)
		{
			try
			{
				output.close();
			}
			catch (Exception e)
			{
				// ignore
			}
		}
	}

	/**
	 * Unconditionally close an <code>InputStream</code>.
	 * <p>
	 * Equivalent to {@link InputStream#close()}, except any exceptions will be ignored. This is
	 * typically used in finally blocks.
	 * 
	 * @param input
	 *            the InputStream to close, may be null or already closed
	 */
	public static void closeQuietly(InputStream input)
	{
		if (input != null)
		{
			try
			{
				input.close();
			}
			catch (Exception e)
			{
				// ignore
			}
		}
	}

	/**
	 * Unconditionally close an <code>OutputStream</code>.
	 * <p>
	 * Equivalent to {@link OutputStream#close()}, except any exceptions will be ignored. This is
	 * typically used in finally blocks.
	 * 
	 * @param output
	 *            the OutputStream to close, may be null or already closed
	 */
	public static void closeQuietly(OutputStream output)
	{
		if (output != null)
		{
			try
			{
				output.close();
			}
			catch (Exception e)
			{
				// ignore
			}
		}
	}

	// read toByteArray
	// -----------------------------------------------------------------------
	/**
	 * Get the contents of an <code>InputStream</code> as a <code>byte[]</code>.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedInputStream</code>.
	 * 
	 * @param input
	 *            the <code>InputStream</code> to read from
	 * @return the requested byte array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static byte[] toByteArray(InputStream input) throws IOException
	{
		ByteArrayOutputStream output = new ByteArrayOutputStream();
		copy(input, output);
		return output.toByteArray();
	}

	/**
	 * Get the contents of a <code>Reader</code> as a <code>byte[]</code> using the default
	 * character encoding of the platform.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedReader</code>.
	 * 
	 * @param input
	 *            the <code>Reader</code> to read from
	 * @return the requested byte array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static byte[] toByteArray(Reader input) throws IOException
	{
		ByteArrayOutputStream output = new ByteArrayOutputStream();
		copy(input, output);
		return output.toByteArray();
	}

	/**
	 * Get the contents of a <code>Reader</code> as a <code>byte[]</code> using the specified
	 * character encoding.
	 * <p>
	 * Character encoding names can be found at <a
	 * href="http://www.iana.org/assignments/character-sets">IANA</a>.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedReader</code>.
	 * 
	 * @param input
	 *            the <code>Reader</code> to read from
	 * @param encoding
	 *            the encoding to use, null means platform default
	 * @return the requested byte array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 * @since 1.1
	 */
	public static byte[] toByteArray(Reader input, String encoding) throws IOException
	{
		ByteArrayOutputStream output = new ByteArrayOutputStream();
		copy(input, output, encoding);
		return output.toByteArray();
	}

	// read char[]
	// -----------------------------------------------------------------------
	/**
	 * Get the contents of an <code>InputStream</code> as a character array using the default
	 * character encoding of the platform.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedInputStream</code>.
	 * 
	 * @param is
	 *            the <code>InputStream</code> to read from
	 * @return the requested character array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static char[] toCharArray(InputStream is) throws IOException
	{
		CharArrayWriter output = new CharArrayWriter();
		copy(is, output);
		return output.toCharArray();
	}

	/**
	 * Get the contents of an <code>InputStream</code> as a character array using the specified
	 * character encoding.
	 * <p>
	 * Character encoding names can be found at <a
	 * href="http://www.iana.org/assignments/character-sets">IANA</a>.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedInputStream</code>.
	 * 
	 * @param is
	 *            the <code>InputStream</code> to read from
	 * @param encoding
	 *            the encoding to use, null means platform default
	 * @return the requested character array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static char[] toCharArray(InputStream is, String encoding) throws IOException
	{
		CharArrayWriter output = new CharArrayWriter();
		copy(is, output, encoding);
		return output.toCharArray();
	}

	/**
	 * Get the contents of a <code>Reader</code> as a character array.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedReader</code>.
	 * 
	 * @param input
	 *            the <code>Reader</code> to read from
	 * @return the requested character array
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static char[] toCharArray(Reader input) throws IOException
	{
		CharArrayWriter sw = new CharArrayWriter();
		copy(input, sw);
		return sw.toCharArray();
	}

	// read toString
	// -----------------------------------------------------------------------
	/**
	 * Get the contents of an <code>InputStream</code> as a String using the default character
	 * encoding of the platform.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedInputStream</code>.
	 * 
	 * @param input
	 *            the <code>InputStream</code> to read from
	 * @return the requested String
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static String toString(InputStream input) throws IOException
	{
		StringWriter sw = new StringWriter();
		copy(input, sw);
		return sw.toString();
	}

	/**
	 * Get the contents of an <code>InputStream</code> as a String using the specified character
	 * encoding.
	 * <p>
	 * Character encoding names can be found at <a
	 * href="http://www.iana.org/assignments/character-sets">IANA</a>.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedInputStream</code>.
	 * 
	 * @param input
	 *            the <code>InputStream</code> to read from
	 * @param encoding
	 *            the encoding to use, null means platform default
	 * @return the requested String
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static String toString(InputStream input, String encoding) throws IOException
	{
		StringWriter sw = new StringWriter();
		copy(input, sw, encoding);
		return sw.toString();
	}

	/**
	 * Get the contents of a <code>Reader</code> as a String.
	 * <p>
	 * This method buffers the input internally, so there is no need to use a
	 * <code>BufferedReader</code>.
	 * 
	 * @param input
	 *            the <code>Reader</code> to read from
	 * @return the requested String
	 * @throws NullPointerException
	 *             if the input is null
	 * @throws IOException
	 *             if an I/O error occurs
	 */
	public static String toString(Reader input) throws IOException
	{
		StringWriter sw = new StringWriter();
		copy(input, sw);
		return sw.toString();
	}

	// write byte[]
	// -----------------------------------------------------------------------
	/**
	 * Writes bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
	 * 
	 * @param data
	 *            the byte array to write, do not modify during output, null ignored
	 * @param output
	 *            the <code>OutputStream</code> to write to
	 * @throws NullPointerException
	 *             if output is null
	 * @throws IOException
	 *             if an I/O error occurs
	 * @since 1.1
	 */
	public static void write(byte[] data, OutputStream output) throws IOException
	{
		if (data != null)
		{
			output.write(data);
		}
	}

	/**
	 * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code> using the
	 * default character encoding of the platform.
	 * <p>
	 * This method uses {@link String#String(byte[])}.
	 * 
	 * @param data
	 *            the byte array to write, do not modify during output, null ignored
	 * @param output
	 *            the <code>Writer</code> to write to
	 * @throws NullPointerException
	 *             if output is null
	 * @throws IOException
	 *             if an I/O error occurs
	 * @since 1.1
	 */
	public static void write(byte[] data, Writer output) throws IOException
	{
		if (data != null)
		{
			output.write(new String(data));
		}
	}

	/**
	 * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code> using the
	 * specified character encoding.
	 * <p>
	 * Character encoding names can be found at <a
	 * href="http://www.iana.org/assignments/character-sets">IANA</a>.
	 * <p>
	 * This method uses {@link String#String(byte[], String)}.
	 * 
	 * @param data
	 *            the byte array to write, do not modify during output, null ignored
	 * @param output
	 *            the <code>Writer</code> to write to
	 * @param encoding
	 *            the encoding to use, null means platform default
	 * @throws NullPointerException
	 *             if output is null
	 * @throws IOException
	 *             if an I/O error occurs
	 * @since 1.1
	 */
	public static void write(byte[] data, Writer output, String encoding) throws IOException
	{
		if (data != null)
		{
			if (encoding == null)
			{
				write(data, output);
			}
			else
			{
				output.write(new String(data, encoding));
			}
		}
	}

	// write char[]
	// -----------------------------------------------------------------------
	/**
	 * Writes chars from a <code>char[]</code> to a <code>Writer</code> using the default
	 * character encoding of the platform.
	 * 
	 * @param data
	 *            the char array to write, do not modify during output, null ignored
	 * @param output
	 *            the <code>Writer</code> to write to
	 * @throws NullPointerException
	 *             if output is null
	 * @throws IOException
	 *             if an I/O error occurs
	 * @since 1.1
	 */
	public static void write(char[] data, Writer output) throws IOException
	{
		if (data != null)
		{
			output.write(data);
		}
	}

	/**
	 * Writes chars from a <code>char[]</code> to bytes on an <code>OutputStream</code>.
	 * <p>