338 lines
12 KiB
Java
338 lines
12 KiB
Java
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/*
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* Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.io;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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import java.util.Objects;
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/**
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* This class implements an output stream in which the data is
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* written into a byte array. The buffer automatically grows as data
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* is written to it.
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* The data can be retrieved using {@code toByteArray()} and
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* {@code toString()}.
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* <p>
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* Closing a {@code ByteArrayOutputStream} has no effect. The methods in
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* this class can be called after the stream has been closed without
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* generating an {@code IOException}.
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*
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* @author Arthur van Hoff
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* @since 1.0
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*/
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public class ByteArrayOutputStream extends OutputStream {
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/**
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* The buffer where data is stored.
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*/
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protected byte buf[];
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/**
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* The number of valid bytes in the buffer.
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*/
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protected int count;
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/**
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* Creates a new {@code ByteArrayOutputStream}. The buffer capacity is
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* initially 32 bytes, though its size increases if necessary.
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*/
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public ByteArrayOutputStream() {
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this(32);
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}
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/**
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* Creates a new {@code ByteArrayOutputStream}, with a buffer capacity of
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* the specified size, in bytes.
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*
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* @param size the initial size.
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* @throws IllegalArgumentException if size is negative.
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*/
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public ByteArrayOutputStream(int size) {
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if (size < 0) {
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throw new IllegalArgumentException("Negative initial size: "
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+ size);
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}
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buf = new byte[size];
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}
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/**
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* Increases the capacity if necessary to ensure that it can hold
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* at least the number of elements specified by the minimum
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* capacity argument.
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*
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* @param minCapacity the desired minimum capacity
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* @throws OutOfMemoryError if {@code minCapacity < 0}. This is
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* interpreted as a request for the unsatisfiably large capacity
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* {@code (long) Integer.MAX_VALUE + (minCapacity - Integer.MAX_VALUE)}.
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*/
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private void ensureCapacity(int minCapacity) {
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// overflow-conscious code
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if (minCapacity - buf.length > 0)
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grow(minCapacity);
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}
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/**
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* The maximum size of array to allocate.
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* Some VMs reserve some header words in an array.
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* Attempts to allocate larger arrays may result in
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* OutOfMemoryError: Requested array size exceeds VM limit
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*/
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private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
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/**
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* Increases the capacity to ensure that it can hold at least the
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* number of elements specified by the minimum capacity argument.
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*
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* @param minCapacity the desired minimum capacity
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*/
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private void grow(int minCapacity) {
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// overflow-conscious code
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int oldCapacity = buf.length;
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int newCapacity = oldCapacity << 1;
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if (newCapacity - minCapacity < 0)
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newCapacity = minCapacity;
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if (newCapacity - MAX_ARRAY_SIZE > 0)
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newCapacity = hugeCapacity(minCapacity);
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buf = Arrays.copyOf(buf, newCapacity);
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}
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private static int hugeCapacity(int minCapacity) {
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if (minCapacity < 0) // overflow
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throw new OutOfMemoryError();
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return (minCapacity > MAX_ARRAY_SIZE) ?
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Integer.MAX_VALUE :
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MAX_ARRAY_SIZE;
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}
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/**
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* Writes the specified byte to this {@code ByteArrayOutputStream}.
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*
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* @param b the byte to be written.
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*/
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public synchronized void write(int b) {
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ensureCapacity(count + 1);
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buf[count] = (byte) b;
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count += 1;
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}
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/**
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* Writes {@code len} bytes from the specified byte array
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* starting at offset {@code off} to this {@code ByteArrayOutputStream}.
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*
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* @param b the data.
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* @param off the start offset in the data.
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* @param len the number of bytes to write.
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* @throws NullPointerException if {@code b} is {@code null}.
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* @throws IndexOutOfBoundsException if {@code off} is negative,
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* {@code len} is negative, or {@code len} is greater than
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* {@code b.length - off}
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*/
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public synchronized void write(byte b[], int off, int len) {
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Objects.checkFromIndexSize(off, len, b.length);
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ensureCapacity(count + len);
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System.arraycopy(b, off, buf, count, len);
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count += len;
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}
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/**
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* Writes the complete contents of the specified byte array
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* to this {@code ByteArrayOutputStream}.
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*
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* @apiNote
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* This method is equivalent to {@link #write(byte[],int,int)
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* write(b, 0, b.length)}.
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*
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* @param b the data.
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* @throws NullPointerException if {@code b} is {@code null}.
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* @since 11
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*/
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public void writeBytes(byte b[]) {
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write(b, 0, b.length);
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}
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/**
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* Writes the complete contents of this {@code ByteArrayOutputStream} to
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* the specified output stream argument, as if by calling the output
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* stream's write method using {@code out.write(buf, 0, count)}.
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*
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* @param out the output stream to which to write the data.
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* @throws NullPointerException if {@code out} is {@code null}.
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* @throws IOException if an I/O error occurs.
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*/
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public synchronized void writeTo(OutputStream out) throws IOException {
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out.write(buf, 0, count);
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}
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/**
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* Resets the {@code count} field of this {@code ByteArrayOutputStream}
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* to zero, so that all currently accumulated output in the
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* output stream is discarded. The output stream can be used again,
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* reusing the already allocated buffer space.
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*
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* @see java.io.ByteArrayInputStream#count
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*/
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public synchronized void reset() {
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count = 0;
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}
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/**
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* Creates a newly allocated byte array. Its size is the current
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* size of this output stream and the valid contents of the buffer
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* have been copied into it.
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*
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* @return the current contents of this output stream, as a byte array.
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* @see java.io.ByteArrayOutputStream#size()
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*/
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public synchronized byte[] toByteArray() {
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return Arrays.copyOf(buf, count);
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}
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/**
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* Returns the current size of the buffer.
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*
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* @return the value of the {@code count} field, which is the number
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* of valid bytes in this output stream.
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* @see java.io.ByteArrayOutputStream#count
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*/
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public synchronized int size() {
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return count;
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}
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/**
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* Converts the buffer's contents into a string decoding bytes using the
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* platform's default character set. The length of the new {@code String}
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* is a function of the character set, and hence may not be equal to the
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* size of the buffer.
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*
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* <p> This method always replaces malformed-input and unmappable-character
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* sequences with the default replacement string for the platform's
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* default character set. The {@linkplain java.nio.charset.CharsetDecoder}
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* class should be used when more control over the decoding process is
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* required.
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*
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* @return String decoded from the buffer's contents.
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* @since 1.1
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*/
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public synchronized String toString() {
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return new String(buf, 0, count);
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}
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/**
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* Converts the buffer's contents into a string by decoding the bytes using
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* the named {@link java.nio.charset.Charset charset}.
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*
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* <p> This method is equivalent to {@code #toString(charset)} that takes a
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* {@link java.nio.charset.Charset charset}.
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*
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* <p> An invocation of this method of the form
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*
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* <pre> {@code
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* ByteArrayOutputStream b = ...
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* b.toString("UTF-8")
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* }
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* </pre>
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*
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* behaves in exactly the same way as the expression
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*
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* <pre> {@code
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* ByteArrayOutputStream b = ...
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* b.toString(StandardCharsets.UTF_8)
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* }
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* </pre>
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*
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*
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* @param charsetName the name of a supported
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* {@link java.nio.charset.Charset charset}
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* @return String decoded from the buffer's contents.
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* @throws UnsupportedEncodingException
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* If the named charset is not supported
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* @since 1.1
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*/
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public synchronized String toString(String charsetName)
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throws UnsupportedEncodingException
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{
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return new String(buf, 0, count, charsetName);
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}
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/**
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* Converts the buffer's contents into a string by decoding the bytes using
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* the specified {@link java.nio.charset.Charset charset}. The length of the new
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* {@code String} is a function of the charset, and hence may not be equal
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* to the length of the byte array.
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*
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* <p> This method always replaces malformed-input and unmappable-character
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* sequences with the charset's default replacement string. The {@link
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* java.nio.charset.CharsetDecoder} class should be used when more control
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* over the decoding process is required.
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*
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* @param charset the {@linkplain java.nio.charset.Charset charset}
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* to be used to decode the {@code bytes}
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* @return String decoded from the buffer's contents.
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* @since 10
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*/
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public synchronized String toString(Charset charset) {
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return new String(buf, 0, count, charset);
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}
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/**
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* Creates a newly allocated string. Its size is the current size of
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* the output stream and the valid contents of the buffer have been
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* copied into it. Each character <i>c</i> in the resulting string is
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* constructed from the corresponding element <i>b</i> in the byte
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* array such that:
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* <blockquote><pre>{@code
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* c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))
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* }</pre></blockquote>
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*
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* @deprecated This method does not properly convert bytes into characters.
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* As of JDK 1.1, the preferred way to do this is via the
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* {@link #toString(String charsetName)} or {@link #toString(Charset charset)}
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* method, which takes an encoding-name or charset argument,
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* or the {@code toString()} method, which uses the platform's default
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* character encoding.
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*
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* @param hibyte the high byte of each resulting Unicode character.
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* @return the current contents of the output stream, as a string.
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* @see java.io.ByteArrayOutputStream#size()
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* @see java.io.ByteArrayOutputStream#toString(String)
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* @see java.io.ByteArrayOutputStream#toString()
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*/
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@Deprecated
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public synchronized String toString(int hibyte) {
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return new String(buf, hibyte, 0, count);
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}
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/**
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* Closing a {@code ByteArrayOutputStream} has no effect. The methods in
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* this class can be called after the stream has been closed without
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* generating an {@code IOException}.
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*/
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public void close() throws IOException {
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}
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}
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