net.hasor.utils.io.output.ByteArrayOutputStream Maven / Gradle / Ivy
/*
* 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 net.hasor.utils.io.output;
import net.hasor.utils.io.input.ClosedInputStream;
import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* This class implements an output stream in which the data is
* written into a byte array. The buffer automatically grows as data
* is written to it.
*
* The data can be retrieved using toByteArray() and
* toString().
*
* Closing a ByteArrayOutputStream has no effect. The methods in
* this class can be called after the stream has been closed without
* generating an IOException.
*
* This is an alternative implementation of the {@link java.io.ByteArrayOutputStream}
* class. The original implementation only allocates 32 bytes at the beginning.
* As this class is designed for heavy duty it starts at 1024 bytes. In contrast
* to the original it doesn't reallocate the whole memory block but allocates
* additional buffers. This way no buffers need to be garbage collected and
* the contents don't have to be copied to the new buffer. This class is
* designed to behave exactly like the original. The only exception is the
* deprecated toString(int) method that has been ignored.
*
* @version $Id: ByteArrayOutputStream.java 1304052 2012-03-22 20:55:29Z ggregory $
*/
public class ByteArrayOutputStream extends OutputStream {
/** A singleton empty byte array. */
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
/** The list of buffers, which grows and never reduces. */
private final List buffers = new ArrayList();
/** The index of the current buffer. */
private int currentBufferIndex;
/** The total count of bytes in all the filled buffers. */
private int filledBufferSum;
/** The current buffer. */
private byte[] currentBuffer;
/** The total count of bytes written. */
private int count;
/**
* Creates a new byte array output stream. The buffer capacity is
* initially 1024 bytes, though its size increases if necessary.
*/
public ByteArrayOutputStream() {
this(1024);
}
/**
* Creates a new byte array output stream, with a buffer capacity of
* the specified size, in bytes.
*
* @param size the initial size
* @throws IllegalArgumentException if size is negative
*/
public ByteArrayOutputStream(final int size) {
if (size < 0) {
throw new IllegalArgumentException("Negative initial size: " + size);
}
synchronized (this) {
this.needNewBuffer(size);
}
}
/**
* Makes a new buffer available either by allocating
* a new one or re-cycling an existing one.
*
* @param newcount the size of the buffer if one is created
*/
private void needNewBuffer(final int newcount) {
if (this.currentBufferIndex < this.buffers.size() - 1) {
//Recycling old buffer
this.filledBufferSum += this.currentBuffer.length;
this.currentBufferIndex++;
this.currentBuffer = this.buffers.get(this.currentBufferIndex);
} else {
//Creating new buffer
int newBufferSize;
if (this.currentBuffer == null) {
newBufferSize = newcount;
this.filledBufferSum = 0;
} else {
newBufferSize = Math.max(this.currentBuffer.length << 1, newcount - this.filledBufferSum);
this.filledBufferSum += this.currentBuffer.length;
}
this.currentBufferIndex++;
this.currentBuffer = new byte[newBufferSize];
this.buffers.add(this.currentBuffer);
}
}
/**
* Write the bytes to byte array.
* @param b the bytes to write
* @param off The start offset
* @param len The number of bytes to write
*/
@Override
public void write(final byte[] b, final int off, final int len) {
if (off < 0 || off > b.length || len < 0 || off + len > b.length || off + len < 0) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
synchronized (this) {
int newcount = this.count + len;
int remaining = len;
int inBufferPos = this.count - this.filledBufferSum;
while (remaining > 0) {
int part = Math.min(remaining, this.currentBuffer.length - inBufferPos);
System.arraycopy(b, off + len - remaining, this.currentBuffer, inBufferPos, part);
remaining -= part;
if (remaining > 0) {
this.needNewBuffer(newcount);
inBufferPos = 0;
}
}
this.count = newcount;
}
}
/**
* Write a byte to byte array.
* @param b the byte to write
*/
@Override
public synchronized void write(final int b) {
int inBufferPos = this.count - this.filledBufferSum;
if (inBufferPos == this.currentBuffer.length) {
this.needNewBuffer(this.count + 1);
inBufferPos = 0;
}
this.currentBuffer[inBufferPos] = (byte) b;
this.count++;
}
/**
* Writes the entire contents of the specified input stream to this
* byte stream. Bytes from the input stream are read directly into the
* internal buffers of this streams.
*
* @param in the input stream to read from
* @return total number of bytes read from the input stream
* (and written to this stream)
* @throws IOException if an I/O error occurs while reading the input stream
* @since 1.4
*/
public synchronized int write(final InputStream in) throws IOException {
int readCount = 0;
int inBufferPos = this.count - this.filledBufferSum;
int n = in.read(this.currentBuffer, inBufferPos, this.currentBuffer.length - inBufferPos);
while (n != -1) {
readCount += n;
inBufferPos += n;
this.count += n;
if (inBufferPos == this.currentBuffer.length) {
this.needNewBuffer(this.currentBuffer.length);
inBufferPos = 0;
}
n = in.read(this.currentBuffer, inBufferPos, this.currentBuffer.length - inBufferPos);
}
return readCount;
}
/**
* Return the current size of the byte array.
* @return the current size of the byte array
*/
public synchronized int size() {
return this.count;
}
/**
* Closing a ByteArrayOutputStream has no effect. The methods in
* this class can be called after the stream has been closed without
* generating an IOException.
*
* @throws IOException never (this method should not declare this exception
* but it has to now due to backwards compatability)
*/
@Override
public void close() throws IOException {
//nop
}
/**
* @see java.io.ByteArrayOutputStream#reset()
*/
public synchronized void reset() {
this.count = 0;
this.filledBufferSum = 0;
this.currentBufferIndex = 0;
this.currentBuffer = this.buffers.get(this.currentBufferIndex);
}
/**
* Writes the entire contents of this byte stream to the
* specified output stream.
*
* @param out the output stream to write to
* @throws IOException if an I/O error occurs, such as if the stream is closed
* @see java.io.ByteArrayOutputStream#writeTo(OutputStream)
*/
public synchronized void writeTo(final OutputStream out) throws IOException {
int remaining = this.count;
for (byte[] buf : this.buffers) {
int c = Math.min(buf.length, remaining);
out.write(buf, 0, c);
remaining -= c;
if (remaining == 0) {
break;
}
}
}
/**
* Fetches entire contents of an InputStream and represent
* same data as result InputStream.
*
* This method is useful where,
*
* - Source InputStream is slow.
* - It has network resources associated, so we cannot keep it open for
* long time.
* - It has network timeout associated.
*
* It can be used in favor of {@link #toByteArray()}, since it
* avoids unnecessary allocation and copy of byte[].
* This method buffers the input internally, so there is no need to use a
* BufferedInputStream.
*
* @param input Stream to be fully buffered.
* @return A fully buffered stream.
* @throws IOException if an I/O error occurs
* @since 2.0
*/
public static InputStream toBufferedInputStream(final InputStream input) throws IOException {
ByteArrayOutputStream output = new ByteArrayOutputStream();
output.write(input);
return output.toBufferedInputStream();
}
/**
* Gets the current contents of this byte stream as a Input Stream. The
* returned stream is backed by buffers of this stream,
* avoiding memory allocation and copy, thus saving space and time.
*
* @return the current contents of this output stream.
* @see java.io.ByteArrayOutputStream#toByteArray()
* @see #reset()
* @since 2.0
*/
private InputStream toBufferedInputStream() {
int remaining = this.count;
if (remaining == 0) {
return new ClosedInputStream();
}
List list = new ArrayList(this.buffers.size());
for (byte[] buf : this.buffers) {
int c = Math.min(buf.length, remaining);
list.add(new ByteArrayInputStream(buf, 0, c));
remaining -= c;
if (remaining == 0) {
break;
}
}
return new SequenceInputStream(Collections.enumeration(list));
}
/**
* Gets the curent contents of this byte stream as a byte array.
* The result is independent of this stream.
*
* @return the current contents of this output stream, as a byte array
* @see java.io.ByteArrayOutputStream#toByteArray()
*/
public synchronized byte[] toByteArray() {
int remaining = this.count;
if (remaining == 0) {
return ByteArrayOutputStream.EMPTY_BYTE_ARRAY;
}
byte newbuf[] = new byte[remaining];
int pos = 0;
for (byte[] buf : this.buffers) {
int c = Math.min(buf.length, remaining);
System.arraycopy(buf, 0, newbuf, pos, c);
pos += c;
remaining -= c;
if (remaining == 0) {
break;
}
}
return newbuf;
}
/**
* Gets the curent contents of this byte stream as a string.
* @return the contents of the byte array as a String
* @see java.io.ByteArrayOutputStream#toString()
*/
@Override
public String toString() {
return new String(this.toByteArray());
}
/**
* Gets the curent contents of this byte stream as a string
* using the specified encoding.
*
* @param enc the name of the character encoding
* @return the string converted from the byte array
* @throws UnsupportedEncodingException if the encoding is not supported
* @see java.io.ByteArrayOutputStream#toString(String)
*/
public String toString(final String enc) throws UnsupportedEncodingException {
return new String(this.toByteArray(), enc);
}
}