Java/File Input Output/ByteArrayOutputStream
Содержание
An unsynchronized version of java.io.ByteArrayOutputStream
<source lang="java">
/* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
* * This program and the accompanying materials are made available under * the terms of the Common Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/cpl-v10.html * * $Id: ByteArrayOStream.java,v 1.1.1.1 2004/05/09 16:57:52 vlad_r Exp $ */
import java.io.IOException; import java.io.OutputStream;
// ---------------------------------------------------------------------------- /**
* An unsynchronized version of java.io.ByteArrayOutputStream that can expose * the underlying byte array without a defensive clone and can also be converted* to a {@link ByteArrayIStream} without intermediate array copies.
* * All argument validation is disabled in release mode.<p> * * NOTE: copy-on-write not supported * * @author (C) 2001, Vlad Roubtsov */ public final class ByteArrayOStream extends OutputStream { // public: ................................................................ /** * Callee takes ownership of "buf". */ public ByteArrayOStream (final int initialCapacity) { m_buf = new byte [initialCapacity]; } public final void write2 (final int b1, final int b2) { final int pos = m_pos; final int capacity = pos + 2; byte [] mbuf = m_buf; final int mbuflen = mbuf.length; if (mbuflen < capacity) { final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; else System.arraycopy (mbuf, 0, newbuf, 0, pos); m_buf = mbuf = newbuf; } mbuf [pos] = (byte) b1; mbuf [pos + 1] = (byte) b2; m_pos = capacity; } public final void write3 (final int b1, final int b2, final int b3) { final int pos = m_pos; final int capacity = pos + 3; byte [] mbuf = m_buf; final int mbuflen = mbuf.length; if (mbuflen < capacity) { final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; else System.arraycopy (mbuf, 0, newbuf, 0, pos); m_buf = mbuf = newbuf; } mbuf [pos] = (byte) b1; mbuf [pos + 1] = (byte) b2; mbuf [pos + 2] = (byte) b3; m_pos = capacity; } public final void write4 (final int b1, final int b2, final int b3, final int b4) { final int pos = m_pos; final int capacity = pos + 4; byte [] mbuf = m_buf; final int mbuflen = mbuf.length; if (mbuflen < capacity) { final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; else System.arraycopy (mbuf, 0, newbuf, 0, pos); m_buf = mbuf = newbuf; } mbuf [pos] = (byte) b1; mbuf [pos + 1] = (byte) b2; mbuf [pos + 2] = (byte) b3; mbuf [pos + 3] = (byte) b4; m_pos = capacity; } public final void writeTo (final OutputStream out) throws IOException { out.write (m_buf, 0, m_pos); } // public final void readFully (final InputStream in) // throws IOException // { // while (true) // { // int chunk = in.available (); // // System.out.println ("available = " + chunk); // // // TODO: this case is handled poorly (on EOF) // if (chunk == 0) chunk = READ_CHUNK_SIZE; // // // read at least "available" bytes: extend the capacity as needed // // int free = m_buf.length - m_pos; // // final int read; // if (free > chunk) // { // // try reading more than "chunk" anyway: // read = in.read (m_buf, m_pos, free); // } // else // { // // extend the capacity to match "chunk": // { // System.out.println ("reallocation"); // final byte [] newbuf = new byte [m_pos + chunk]; // // if (m_pos < NATIVE_COPY_THRESHOLD) // for (int i = 0; i < m_pos; ++ i) newbuf [i] = m_buf [i]; // else // System.arraycopy (m_buf, 0, newbuf, 0, m_pos); // // m_buf = newbuf; // } // // read = in.read (m_buf, m_pos, chunk); // } // // if (read < 0) // break; // else // m_pos += read; // } // } // public final void addCapacity (final int extraCapacity) // { // final int pos = m_pos; // final int capacity = pos + extraCapacity; // byte [] mbuf = m_buf; // final int mbuflen = mbuf.length; // // if (mbuflen < capacity) // { // final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; // // if (pos < NATIVE_COPY_THRESHOLD) // for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; // else // System.arraycopy (mbuf, 0, newbuf, 0, pos); // // m_buf = newbuf; // } // } public final byte [] getByteArray () { return m_buf; } /** * * @return [result.length = size()] */ public final byte [] copyByteArray () { final int pos = m_pos; final byte [] result = new byte [pos]; final byte [] mbuf = m_buf; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) result [i] = mbuf [i]; else System.arraycopy (mbuf, 0, result, 0, pos); return result; } public final int size () { return m_pos; } public final int capacity () { return m_buf.length; } /** * Does not reduce the current capacity. */ public final void reset () { m_pos = 0; } // OutputStream: public final void write (final int b) { final int pos = m_pos; final int capacity = pos + 1; byte [] mbuf = m_buf; final int mbuflen = mbuf.length; if (mbuflen < capacity) { final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; else System.arraycopy (mbuf, 0, newbuf, 0, pos); m_buf = mbuf = newbuf; } mbuf [pos] = (byte) b; m_pos = capacity; } public final void write (final byte [] buf, final int offset, final int length) { final int pos = m_pos; final int capacity = pos + length; byte [] mbuf = m_buf; final int mbuflen = mbuf.length; if (mbuflen < capacity) { final byte [] newbuf = new byte [Math.max (mbuflen << 1, capacity)]; if (pos < NATIVE_COPY_THRESHOLD) for (int i = 0; i < pos; ++ i) newbuf [i] = mbuf [i]; else System.arraycopy (mbuf, 0, newbuf, 0, pos); m_buf = mbuf = newbuf; } if (length < NATIVE_COPY_THRESHOLD) for (int i = 0; i < length; ++ i) mbuf [pos + i] = buf [offset + i]; else System.arraycopy (buf, offset, mbuf, pos, length); m_pos = capacity; } /** * Equivalent to {@link #reset()}. */ public final void close () { reset (); } // protected: ............................................................. // package: ............................................................... // private: ............................................................... private byte [] m_buf; private int m_pos; // private static final int READ_CHUNK_SIZE = 16 * 1024; private static final int NATIVE_COPY_THRESHOLD = 9; } // end of class // ---------------------------------------------------------------------------- </source>
A speedy implementation of ByteArrayOutputStream.
<source lang="java">
/*
* Copyright (c) 2002-2003 by OpenSymphony * All rights reserved. */
import java.io.IOException; import java.io.OutputStream; import java.io.RandomAccessFile; import java.io.Writer; import java.util.Iterator; import java.util.LinkedList;
/**
* 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 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;
}
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;
}
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;
}
}
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 ONLY 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 bufferToWriteLen of bytes from bufferToWrite to
* out 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();
}
buffers.addLast(buffer);
buffer = new byte[blockSize];
size += index;
index = 0;
}
} ////////////////////////////
import java.io.IOException; import javax.servlet.jsp.JspWriter; /**
* A test class for {@link webwork.util.FastByteArrayOutputStream}
*
* @author Brad Baker (Atlassian)
* @since $Date$ $Id$
*/
public class FastByteArrayOutputStreamTestCase extends AbstractEncodingTestCase {
public void testLatinCharsets() throws Exception
{
assertEncoding(ASCII_TEXT, LATIN);
assertEncoding(ASCII_TEXT, ASCII);
}
public void testRussianCharsets() throws Exception
{
assertEncoding(RUSSIAN_DESC_SHORT, KOI8_R);
assertEncoding(RUSSIAN_DESC1, KOI8_R);
assertEncoding(RUSSIAN_DESC_SHORT, WINDOWS_CYRILLIC);
assertEncoding(RUSSIAN_DESC1, WINDOWS_CYRILLIC);
}
public void testUnicodeCharsets() throws Exception
{
String[] testStrs = {ASCII_TEXT_SHORT, ASCII_TEXT, RUSSIAN_DESC_SHORT, RUSSIAN_DESC1, CHINESE_TIMETRACKING, HUNGRIAN_APPLET_PROBLEM, };
String[] encodings = { UTF_8, UTF_16, UBIG_ENDIAN, ULITTLE_ENDIAN, UBIG_ENDIAN_UNMARKED, ULITTLE_ENDIAN_UNMARKED };
assertEncodings(testStrs, encodings);
}
protected void implementEncodingTest(final String srcStr, final String encoding, final int bufferSize)
throws Exception
{
FastByteArrayOutputStream bout = new FastByteArrayOutputStream(bufferSize);
byte[] bytes = srcStr.getBytes(encoding);
bout.write(bytes);
JspWriter writer = new StringCapturingJspWriter();
bout.writeTo(writer, encoding);
String actualStr = writer.toString();
String expectedStr = new String(bytes, encoding);
assertTheyAreEqual(expectedStr, actualStr, encoding);
}
/**
* Before it was changed to use {@link java.nio.charset.CharsetDecoder} is took an this time
* <p/>
* Total Call Time = 1112.0ms
* Average Call Time = 0.001112ms
* <p/>
* Now with the change it takes this time
* <p/>
* <p/>
* The idea is that it did not get significantly worse in performance
*
* @throws IOException
*/
public void testPerformanceOfWriteToJspWriter() throws IOException
{
final String NINEK_STR = makeRoughly(ASCII, 9 * K);
final String FIFTYK_STR = makeRoughly(ASCII, 50 * K);
final String ONEHUNDREDK_STR = makeRoughly(ASCII, 100 * K);
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With < than 8K of data";
}
public String getText(final int times)
{
return ASCII_TEXT;
}
});
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With > than 8K of data";
}
public String getText(final int times)
{
return NINEK_STR;
}
});
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With a 2/3 mix of small data and 1/3 > 8K of data";
}
public String getText(final int times)
{
if (times % 3 == 0)
{
return NINEK_STR;
}
return ASCII_TEXT;
}
});
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With a 1/2 mix of small data and 1/2 > 8K of data";
}
public String getText(final int times)
{
if (times % 2 == 0)
{
return NINEK_STR;
}
return ASCII_TEXT;
}
});
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With 50K of data";
}
public String getText(final int times)
{
return FIFTYK_STR;
}
});
testPerformanceOfWriteToJspWriter(new TextSource()
{
public String getDesc()
{
return "With 100K of data";
}
public String getText(final int times)
{
return ONEHUNDREDK_STR;
}
});
}
public void testPerformanceOfWriteToJspWriter(TextSource textSource) throws IOException
{
NoopJspWriter noopJspWriter = new NoopJspWriter();
String[] methods = {
"writeTo (using hueristics)",
"writeToViaSmoosh",
};
System.out.println(textSource.getDesc());
System.out.println();
float bestTime = Float.MAX_VALUE;
String bestMethod = methods[0];
for (int methodIndex = 0; methodIndex < methods.length; methodIndex++)
{
String method = methods[methodIndex];
float totalTime = 0;
final int MAX_TIMES = 10;
final int MAX_ITERATIONS = 100;
for (int times = 0; times < MAX_TIMES; times++)
{
String srcText = textSource.getText(times);
for (int i = 0; i < MAX_ITERATIONS; i++)
{
FastByteArrayOutputStream bout = new FastByteArrayOutputStream();
bout.write(srcText.getBytes(UTF_8));
// just time the JspWriter output. And let it warm u first as well
if (times > 3)
{
long then = System.currentTimeMillis();
switch (methodIndex)
{
case 0:
bout.writeTo(noopJspWriter, UTF_8);
break;
case 1:
bout.writeToViaSmoosh(noopJspWriter, UTF_8);
break;
}
long now = System.currentTimeMillis();
totalTime += (now - then);
}
}
}
float avgTime = totalTime / MAX_TIMES / MAX_ITERATIONS;
System.out.println(method + " - Total Call Time = " + totalTime + "ms");
System.out.println(method + " - Average Call Time = " + avgTime + "ms");
System.out.println();
if (avgTime < bestTime) {
bestTime = avgTime;
bestMethod = method;
}
}
System.out.println(bestMethod + " was the best method - Average Call Time = " + bestTime + "ms");
System.out.println("____________________\n");
}
interface TextSource
{
String getDesc();
String getText(int times);
}
static class StringCapturingJspWriter extends NoopJspWriter
{
StringCapturingJspWriter()
{
super(true);
}
}
static class NoopJspWriter extends JspWriter
{
final StringBuffer sb = new StringBuffer();
final boolean capture;
NoopJspWriter()
{
this(false);
}
NoopJspWriter(boolean capture)
{
super(0, false);
this.capture = capture;
}
NoopJspWriter(final int i, final boolean b)
{
super(i, b);
this.capture = false;
}
public String toString()
{
return sb.toString();
}
public void clear() throws IOException
{
}
public void clearBuffer() throws IOException
{
}
public void close() throws IOException
{
}
public void flush() throws IOException
{
}
public int getRemaining()
{
return 0;
}
public void newLine() throws IOException
{
}
public void print(final char c) throws IOException
{
if (capture)
{
sb.append(c);
}
}
public void print(final double v) throws IOException
{
if (capture)
{
sb.append(v);
}
}
public void print(final float v) throws IOException
{
if (capture)
{
sb.append(v);
}
}
public void print(final int i) throws IOException
{
if (capture)
{
sb.append(i);
}
}
public void print(final long l) throws IOException
{
if (capture)
{
sb.append(l);
}
}
public void print(final Object o) throws IOException
{
if (capture)
{
sb.append(o);
}
}
public void print(final String s) throws IOException
{
if (capture)
{
sb.append(s);
}
}
public void print(final boolean b) throws IOException
{
if (capture)
{
sb.append(b);
}
}
public void print(final char[] chars) throws IOException
{
if (capture)
{
sb.append(chars);
}
}
public void println() throws IOException
{
print("\n");
}
public void println(final char c) throws IOException
{
print(c);
println();
}
public void println(final double v) throws IOException
{
print(v);
println();
}
public void println(final float v) throws IOException
{
print(v);
println();
}
public void println(final int i) throws IOException
{
print(i);
println();
}
public void println(final long l) throws IOException
{
print(l);
println();
}
public void println(final Object o) throws IOException
{
print(o);
println();
}
public void println(final String s) throws IOException
{
print(s);
println();
}
public void println(final boolean b) throws IOException
{
print(b);
println();
}
public void println(final char[] chars) throws IOException
{
print(chars);
println();
}
public void write(final char cbuf[], final int off, final int len) throws IOException
{
String s = new String(cbuf, off, len);
print(s);
}
}
}
</source>
Provides true Closable semantics ordinarily missing in a java.io.ByteArrayOutputStream
<source lang="java">
/* Copyright (c) 2001-2009, The HSQL Development Group
* All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the HSQL Development Group nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG, * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.UnsupportedEncodingException; /* $Id: ClosableByteArrayOutputStream.java 2946 2009-03-22 17:44:48Z fredt $ */ /**
* @todo - finer-grained synchronization to reduce average * potential monitor contention */
/**
* Provides true Closable semantics ordinarily missing in a
* {@link java.io.ByteArrayOutputStream}. <p>
*
* Accumulates output in a byte array that automatically grows as needed.<p>
*
* Data is retrieved using toByteArray(),
* toByteArrayInputStream(), toString() and
* toString(encoding). <p>
*
* {@link #close() Closing} a ClosableByteArrayOutputStream prevents
* further write operations, but all other operations may succeed until after
* the first invocation of {@link #free() free()}.<p>
*
* Freeing a ClosableByteArrayOutputStream closes the stream and
* releases the internal buffer, preventing successful invocation of all
* operations, with the exception of size()<tt>, <tt>close(),
* isClosed(), free() and isFreed(). <p>
*
* This class is especially useful when an accumulating output stream must be
* handed off to an extenal client under contract that the stream should
* exhibit true Closable behaviour in response both to internally tracked
* events and to client invocation of the OutputStream.close() method.
*
* @author boucherb@users
* @version 1.9.0
* @since 1.9.0
*/
public class ClosableByteArrayOutputStream extends OutputStream {
/**
* Data buffer.
*/
protected byte[] buf;
/**
* # of valid bytes in buffer.
*/
protected int count;
/**
* Whether this stream is closed.
*/
protected boolean closed;
/**
* Whether this stream is freed.
*/
protected boolean freed;
/**
* Creates a new output stream. <p>
*
* The buffer capacity is initially 32 bytes, though its size increases
* if necessary.
*/
public ClosableByteArrayOutputStream() {
this(32);
}
/**
* Creates a new output stream with a buffer capacity of the specified
* size, in bytes.
*
* @param size the initial size.
* @exception IllegalArgumentException if size is negative.
*/
public ClosableByteArrayOutputStream(int size)
throws IllegalArgumentException {
if (size < 0) {
throw new IllegalArgumentException("Negative initial size: "
+ size); // NOI18N
}
buf = new byte[size];
}
/**
* Writes the specified single byte.
*
* @param b the single byte to be written.
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #close() closed}.
*/
public synchronized void write(int b) throws IOException {
checkClosed();
int newcount = count + 1;
if (newcount > buf.length) {
buf = copyOf(buf, Math.max(buf.length << 1, newcount));
}
buf[count] = (byte) b;
count = newcount;
}
/**
* Writes the specified portion of the designated octet sequence. <p>
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #close() closed}.
*/
public synchronized void write(byte b[], int off,
int len) throws IOException {
checkClosed();
if ((off < 0) || (off > b.length) || (len < 0)
|| ((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
int newcount = count + len;
if (newcount > buf.length) {
buf = copyOf(buf, Math.max(buf.length << 1, newcount));
}
System.arraycopy(b, off, buf, count, len);
count = newcount;
}
/**
* By default, does nothing. <p>
*
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #close() closed}.
*/
public void flush() throws IOException {
checkClosed();
}
/**
* Writes the complete contents of this stream"s accumulated data to the
* specified output stream. <p>
*
* The operation occurs as if by calling out.write(buf, 0, count).
*
* @param out the output stream to which to write the data.
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #free() freed}.
*/
public synchronized void writeTo(OutputStream out) throws IOException {
checkFreed();
out.write(buf, 0, count);
}
/**
* Returns the current capacity of this stream"s data buffer.
*
* @return the length of the internal data array
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #free() freed}.
*/
public synchronized int capacity() throws IOException {
checkFreed();
return buf.length;
}
/**
* Resets the count field of this output stream to zero, so that
* all currently accumulated data is effectively discarded. <p>
*
* Further write operations will reuse the allocated buffer space. <p>
*
* @see #count
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #close() closed}.
*/
public synchronized void reset() throws IOException {
checkClosed();
count = 0;
}
/**
* Attempts to reduce this stream"s capacity to its current size. <p>
*
* If the data buffer is larger than necessary to hold its current sequence
* of bytes, then it may be resized to become more space efficient.
* Calling this method may, but is not required to, affect the value
* returned by a subsequent call to the {@link #capacity()} method. <p>
*
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #free() freed}.
*/
public synchronized void trimToSize() throws IOException {
checkFreed();
if (buf.length > count) {
buf = copyOf(buf, count);
}
}
/**
* Retrieves a copy of this stream"s accumated data, as a byte array.
*
* @return a copy of this stream"s accumated data, as a byte array.
* @see #size()
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #free() freed}.
*/
public synchronized byte[] toByteArray() throws IOException {
checkFreed();
return copyOf(buf, count);
}
/**
* Returns the current size of this stream"s accumated data.
*
* @return the value of the count field, which is the number
* of valid bytes in this output stream.
* @see #count
* @throws java.io.IOException never
*/
public synchronized int size() throws IOException {
return count;
}
/**
* Sets the size of this stream"s accumulated data. <p>
*
* @param newSize the new size
* @throws ArrayIndexOutOfBoundsException if new size is negative
*/
public synchronized void setSize(int newSize) {
if (newSize < 0) {
throw new ArrayIndexOutOfBoundsException(newSize);
} else if (newSize > buf.length) {
buf = copyOf(buf, Math.max(buf.length << 1, newSize));
}
count = newSize;
}
/**
* Performs an effecient (zero-copy) conversion of the data accumulated in
* this output stream to an input stream. <p>
*
* To ensure the future integrity of the resulting input stream, {@link
* #free() free} is invoked upon this output stream as a side-effect.
*
* @return an input stream representing this output stream"s accumulated
* data
* @throws java.io.IOException if an I/O error occurs.
* In particular, an IOException may be thrown
* if this output stream has been {@link #free() freed}.
*/
public synchronized ByteArrayInputStream toByteArrayInputStream()
throws IOException {
checkFreed();
ByteArrayInputStream inputStream = new ByteArrayInputStream(buf, 0,
count);
free();
return inputStream;
}
/**
* Converts this stream"s accumuated data into a string, translating bytes
* into characters according to the platform"s default character encoding.
*
* @return String translated from this stream"s accumuated data.
* @throws RuntimeException may be thrown if this output stream has been
* {@link #free() freed}.
*/
public synchronized String toString() {
try {
checkFreed();
} catch (IOException ex) {
throw new RuntimeException(ex.toString());
}
return new String(buf, 0, count);
}
/**
* Converts this stream"s accumuated data into a string, translating bytes
* into characters according to the specified character encoding.
*
* @return String translated from the buffer"s contents.
* @param enc a character-encoding name.
* @throws java.io.IOException may be thrown if this output stream has been
* {@link #free() freed}.
* @throws UnsupportedEncodingException If the named encoding is not
* supported.
*/
public synchronized String toString(String enc)
throws IOException, UnsupportedEncodingException {
checkFreed();
return new String(buf, 0, count, enc);
}
/**
* Closes this object for further writing. <p>
*
* Other operations may continue to succeed until after the first invocation
* of {@link #free() free()}. <p>
*
* @throws java.io.IOException if an I/O error occurs (default: never)
*/
public synchronized void close() throws IOException {
closed = true;
}
/**
* Retrieves whether this stream is closed. <p>
* @return true if this stream is closed, else false
*/
public synchronized boolean isClosed() {
return closed;
}
/**
* Closes this object and releases the underlying buffer for
* garbage collection. <p>
*
* @throws java.io.IOException if an I/O error occurs while closing
* this stream (default: never).
*/
public synchronized void free() throws IOException {
closed = true;
freed = true;
buf = null;
count = 0;
}
/**
* Retrieves whether this stream is freed. <p>
*
* @return true if this stream is freed; else false.
*/
public synchronized boolean isFreed() {
return freed;
}
/**
* Tests whether this stream is closed. <p>
*
* @throws java.io.IOException if this stream is closed.
*/
protected synchronized void checkClosed() throws IOException {
if (closed) {
throw new IOException("stream is closed."); // NOI18N
}
}
/**
* Tests whether this stream is freed. <p>
*
* @throws java.io.IOException if this stream is freed.
*/
protected synchronized void checkFreed() throws IOException {
if (freed) {
throw new IOException("stream buffer is freed."); // NOI18N
}
}
/**
* Retrieves a copy of original with the given
* newLength. <p>
*
* @param original the object to copy
* @param newLength the length of the copy
* @return copy of original with the given newLength
*/
protected byte[] copyOf(byte[] original, int newLength) {
byte[] copy = new byte[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
}
</source>
Use ByteArrayOutputStream
<source lang="java">
import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; public class ByteArrayIOApp {
public static void main(String args[]) throws IOException {
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
String s = "This is a test.";
for (int i = 0; i < s.length(); ++i)
outStream.write(s.charAt(i));
System.out.println("outstream: " + outStream);
System.out.println("size: " + outStream.size());
ByteArrayInputStream inStream;
inStream = new ByteArrayInputStream(outStream.toByteArray());
int inBytes = inStream.available();
System.out.println("inStream has " + inBytes + " available bytes");
byte inBuf[] = new byte[inBytes];
int bytesRead = inStream.read(inBuf, 0, inBytes);
System.out.println(bytesRead + " bytes were read");
System.out.println("They are: " + new String(inBuf));
}
}
</source>
