/*
* 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 java.io;
import java.util.Arrays;
/**
* A specialized {@link OutputStream} for class for writing content to an
* (internal) byte array. As bytes are written to this stream, the byte array
* may be expanded to hold more bytes. When the writing is considered to be
* finished, a copy of the byte array can be requested from the class.
*
* @see ByteArrayInputStream
*/
public class ByteArrayOutputStream extends OutputStream {
/**
* The byte array containing the bytes written.
*/
protected byte[] buf;
/**
* The number of bytes written.
*/
protected int count;
/**
* Constructs a new ByteArrayOutputStream with a default size of 32 bytes.
* If more than 32 bytes are written to this instance, the underlying byte
* array will expand.
*/
public ByteArrayOutputStream() {
buf = new byte[32];
}
/**
* Constructs a new {@code ByteArrayOutputStream} with a default size of
* {@code size} bytes. If more than {@code size} bytes are written to this
* instance, the underlying byte array will expand.
*
* @param size
* initial size for the underlying byte array, must be
* non-negative.
* @throws IllegalArgumentException
* if {@code size} < 0.
*/
public ByteArrayOutputStream(int size) {
if (size >= 0) {
buf = new byte[size];
} else {
throw new IllegalArgumentException("size < 0");
}
}
/**
* Closes this stream. This releases system resources used for this stream.
*
* @throws IOException
* if an error occurs while attempting to close this stream.
*/
@Override
public void close() throws IOException {
/**
* Although the spec claims "A closed stream cannot perform output
* operations and cannot be reopened.", this implementation must do
* nothing.
*/
super.close();
}
private void expand(int i) {
/* Can the buffer handle @i more bytes, if not expand it */
if (count + i <= buf.length) {
return;
}
byte[] newbuf = new byte[(count + i) * 2];
System.arraycopy(buf, 0, newbuf, 0, count);
buf = newbuf;
}
/**
* Resets this stream to the beginning of the underlying byte array. All
* subsequent writes will overwrite any bytes previously stored in this
* stream.
*/
public synchronized void reset() {
count = 0;
}
/**
* Returns the total number of bytes written to this stream so far.
*
* @return the number of bytes written to this stream.
*/
public int size() {
return count;
}
/**
* Returns the contents of this ByteArrayOutputStream as a byte array. Any
* changes made to the receiver after returning will not be reflected in the
* byte array returned to the caller.
*
* @return this stream's current contents as a byte array.
*/
public synchronized byte[] toByteArray() {
byte[] newArray = new byte[count];
System.arraycopy(buf, 0, newArray, 0, count);
return newArray;
}
/**
* Returns the contents of this ByteArrayOutputStream as a string. Any
* changes made to the receiver after returning will not be reflected in the
* string returned to the caller.
*
* @return this stream's current contents as a string.
*/
@Override
public String toString() {
return new String(buf, 0, count);
}
/**
* Returns the contents of this ByteArrayOutputStream as a string. Each byte
* {@code b} in this stream is converted to a character {@code c} using the
* following function:
* {@code c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))}. This method is
* deprecated and either {@link #toString()} or {@link #toString(String)}
* should be used.
*
* @param hibyte
* the high byte of each resulting Unicode character.
* @return this stream's current contents as a string with the high byte set
* to {@code hibyte}.
* @deprecated Use {@link #toString()}.
*/
@Deprecated
public String toString(int hibyte) {
char[] newBuf = new char[size()];
for (int i = 0; i < newBuf.length; i++) {
newBuf[i] = (char) (((hibyte & 0xff) << 8) | (buf[i] & 0xff));
}
return new String(newBuf);
}
/**
* Returns the contents of this ByteArrayOutputStream as a string converted
* according to the encoding declared in {@code enc}.
*
* @param enc
* a string representing the encoding to use when translating
* this stream to a string.
* @return this stream's current contents as an encoded string.
* @throws UnsupportedEncodingException
* if the provided encoding is not supported.
*/
public String toString(String enc) throws UnsupportedEncodingException {
return new String(buf, 0, count, enc);
}
/**
* Writes {@code count} bytes from the byte array {@code buffer} starting at
* offset {@code index} to this stream.
*
* @param buffer
* the buffer to be written.
* @param offset
* the initial position in {@code buffer} to retrieve bytes.
* @param len
* the number of bytes of {@code buffer} to write.
* @throws NullPointerException
* if {@code buffer} is {@code null}.
* @throws IndexOutOfBoundsException
* if {@code offset < 0} or {@code len < 0}, or if
* {@code offset + len} is greater than the length of
* {@code buffer}.
*/
@Override
public synchronized void write(byte[] buffer, int offset, int len) {
Arrays.checkOffsetAndCount(buffer.length, offset, len);
if (len == 0) {
return;
}
expand(len);
System.arraycopy(buffer, offset, buf, this.count, len);
this.count += len;
}
/**
* Writes the specified byte {@code oneByte} to the OutputStream. Only the
* low order byte of {@code oneByte} is written.
*
* @param oneByte
* the byte to be written.
*/
@Override
public synchronized void write(int oneByte) {
if (count == buf.length) {
expand(1);
}
buf[count++] = (byte) oneByte;
}
/**
* Takes the contents of this stream and writes it to the output stream
* {@code out}.
*
* @param out
* an OutputStream on which to write the contents of this stream.
* @throws IOException
* if an error occurs while writing to {@code out}.
*/
public synchronized void writeTo(OutputStream out) throws IOException {
out.write(buf, 0, count);
}
}