package com.cloudhopper.commons.util;
/*
* #%L
* ch-commons-util
* %%
* Copyright (C) 2012 Cloudhopper by Twitter
* %%
* 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.
* #L%
*/
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.io.Writer;
import java.util.Iterator;
import java.util.LinkedList;
/**
* Originally found here: http://www.java2s.com/Code/Java/File-Input-Output/AspeedyimplementationofByteArrayOutputStream.htm
*
* A speedy implementation of ByteArrayOutputStream. It's not synchronized, and it
* does not copy buffers when it's expanded. There's also no copying of the internal buffer
* if it's contents is extracted with the writeTo(stream) method.
*
* @author Rickard berg
* @author Brat Baker (Atlassian)
* @author Alexey
* @version $Date: 2008-01-19 10:09:56 +0800 (Sat, 19 Jan 2008) $ $Id: FastByteArrayOutputStream.java 3000 2008-01-19 02:09:56Z tm_jee $
*/
public class FastByteArrayOutputStream extends OutputStream {
// Static --------------------------------------------------------
private static final int DEFAULT_BLOCK_SIZE = 8192;
private LinkedList<byte[]> buffers;
// Attributes ----------------------------------------------------
// internal buffer
private byte[] buffer;
// is the stream closed?
private boolean closed;
private int blockSize;
private int index;
private int size;
// Constructors --------------------------------------------------
public FastByteArrayOutputStream() {
this(DEFAULT_BLOCK_SIZE);
}
public FastByteArrayOutputStream(int aSize) {
blockSize = aSize;
buffer = new byte[blockSize];
}
public int getSize() {
return size + index;
}
@Override
public void close() {
closed = true;
}
public byte[] toByteArray() {
byte[] data = new byte[getSize()];
// Check if we have a list of buffers
int pos = 0;
if (buffers != null) {
Iterator iter = buffers.iterator();
while (iter.hasNext()) {
byte[] bytes = (byte[])iter.next();
System.arraycopy(bytes, 0, data, pos, blockSize);
pos += blockSize;
}
}
// write the internal buffer directly
System.arraycopy(buffer, 0, data, pos, index);
return data;
}
@Override
public String toString() {
return new String(toByteArray());
}
// OutputStream overrides ----------------------------------------
public void write(int datum) throws IOException {
if (closed) {
throw new IOException("Stream closed");
} else {
if (index == blockSize) {
addBuffer();
}
// store the byte
buffer[index++] = (byte) datum;
}
}
@Override
public void write(byte[] data, int offset, int length) throws IOException {
if (data == null) {
throw new NullPointerException();
} else if ((offset < 0) || ((offset + length) > data.length) || (length < 0)) {
throw new IndexOutOfBoundsException();
} else if (closed) {
throw new IOException("Stream closed");
} else {
if ((index + length) > blockSize) {
int copyLength;
do {
if (index == blockSize) {
addBuffer();
}
copyLength = blockSize - index;
if (length < copyLength) {
copyLength = length;
}
System.arraycopy(data, offset, buffer, index, copyLength);
offset += copyLength;
index += copyLength;
length -= copyLength;
} while (length > 0);
} else {
// Copy in the subarray
System.arraycopy(data, offset, buffer, index, length);
index += length;
}
}
}
// Public
public void writeTo(OutputStream out) throws IOException {
// Check if we have a list of buffers
if (buffers != null) {
Iterator iter = buffers.iterator();
while (iter.hasNext()) {
byte[] bytes = (byte[]) iter.next();
out.write(bytes, 0, blockSize);
}
}
// write the internal buffer directly
out.write(buffer, 0, index);
}
public void writeTo(RandomAccessFile out) throws IOException {
// Check if we have a list of buffers
if (buffers != null) {
Iterator iter = buffers.iterator();
while (iter.hasNext()) {
byte[] bytes = (byte[]) iter.next();
out.write(bytes, 0, blockSize);
}
}
// write the internal buffer directly
out.write(buffer, 0, index);
}
public void writeTo(Writer out, String encoding) throws IOException {
/*
There is design tradeoff between being fast, correct and using too much memory when decoding bytes to strings.
The rules are thus :
1. if there is only one buffer then its a simple String conversion
REASON : Fast!!!
2. uses full buffer allocation annd System.arrayCopy() to smooosh together the bytes
and then use String conversion
REASON : Fast at the expense of a known amount of memory (eg the used memory * 2)
*/
if (buffers != null) {
// RULE 2 : a balance between using some memory and speed
writeToViaSmoosh(out, encoding);
} else {
// RULE 1 : fastest!
writeToViaString(out, encoding);
}
}
/**
* This can <b>ONLY</b> be called if there is only a single buffer to write, instead
* use {@link #writeTo(java.io.Writer, String)}, which auto detects if
* {@link #writeToViaString(java.io.Writer, String)} is to be used or
* {@link #writeToViaSmoosh(java.io.Writer, String)}.
*
* @param out the JspWriter
* @param encoding the encoding
* @throws IOException
*/
void writeToViaString(Writer out, String encoding) throws IOException {
byte[] bufferToWrite = buffer; // this is always the last buffer to write
int bufferToWriteLen = index; // index points to our place in the last buffer
writeToImpl(out, encoding, bufferToWrite, bufferToWriteLen);
}
/**
* This is recommended to be used where there's more than 1 buffer to write, instead
* use {@link #writeTo(java.io.Writer, String)} which auto detects if
* {@link #writeToViaString(java.io.Writer, String)} is to be used or
* {@link #writeToViaSmoosh(java.io.Writer, String)}.
*
* @param out
* @param encoding
* @throws IOException
*/
void writeToViaSmoosh(Writer out, String encoding) throws IOException {
byte[] bufferToWrite = toByteArray();
int bufferToWriteLen = bufferToWrite.length;
writeToImpl(out, encoding, bufferToWrite, bufferToWriteLen);
}
/**
* Write <code>bufferToWriteLen</code> of bytes from <code>bufferToWrite</code> to
* <code>out</code> encoding it at the same time.
*
* @param out
* @param encoding
* @param bufferToWrite
* @param bufferToWriteLen
* @throws IOException
*/
private void writeToImpl(Writer out, String encoding, byte[] bufferToWrite, int bufferToWriteLen)
throws IOException {
String writeStr;
if (encoding != null) {
writeStr = new String(bufferToWrite, 0, bufferToWriteLen, encoding);
} else {
writeStr = new String(bufferToWrite, 0, bufferToWriteLen);
}
out.write(writeStr);
}
/**
* Create a new buffer and store the
* current one in linked list
*/
protected void addBuffer() {
if (buffers == null) {
buffers = new LinkedList<byte[]>();
}
buffers.addLast(buffer);
buffer = new byte[blockSize];
size += index;
index = 0;
}
}