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/*
* 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 org.apache.nifi.stream.io;
import java.io.InputStream;
/**
* This class performs the same function as java.io.ByteArrayInputStream but does not mark its methods as synchronized
*/
public class ByteArrayInputStream extends InputStream {
/**
* An array of bytes that was provided by the creator of the stream. Elements buf[0] through buf[count-1] are the only bytes that can ever be read from the stream;
* element buf[pos] is the next byte to be read.
*/
protected byte buf[];
/**
* The index of the next character to read from the input stream buffer. This value should always be nonnegative and not larger than the value of count. The next byte to be read from
* the input stream buffer will be buf[pos].
*/
protected int pos;
/**
* The currently marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by
* the mark() method. The current buffer position is set to this point by the reset() method.
*
* If no mark has been set, then the value of mark is the offset passed to the constructor (or 0 if the offset was not supplied).
*
* @since JDK1.1
*/
protected int mark = 0;
/**
* The index one greater than the last valid character in the input stream buffer. This value should always be nonnegative and not larger than the length of buf. It is one greater
* than the position of the last byte within buf that can ever be read from the input stream buffer.
*/
protected int count;
/**
* Creates a ByteArrayInputStream so that it uses buf as its buffer array. The buffer array is not copied. The initial value of pos is 0 and the
* initial value of count is the length of buf.
*
* @param buf the input buffer.
*/
public ByteArrayInputStream(byte buf[]) {
this.buf = buf;
this.pos = 0;
this.count = buf.length;
}
/**
* Creates ByteArrayInputStream that uses buf as its buffer array. The initial value of pos is offset and the initial value of
* count is the minimum of offset+length and buf.length. The buffer array is not copied. The buffer's mark is set to the specified offset.
*
* @param buf the input buffer.
* @param offset the offset in the buffer of the first byte to read.
* @param length the maximum number of bytes to read from the buffer.
*/
public ByteArrayInputStream(byte buf[], int offset, int length) {
this.buf = buf;
this.pos = offset;
this.count = Math.min(offset + length, buf.length);
this.mark = offset;
}
/**
* Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of
* the stream has been reached, the value -1 is returned.
*
* This read method cannot block.
*
* @return the next byte of data, or -1 if the end of the stream has been reached.
*/
@Override
public int read() {
return (pos < count) ? (buf[pos++] & 0xff) : -1;
}
/**
* Reads up to len bytes of data into an array of bytes from this input stream. If pos equals count, then -1 is returned to indicate end of
* file. Otherwise, the number k of bytes read is equal to the smaller of len and count-pos. If k is positive, then bytes buf[pos]
* through buf[pos+k-1] are copied into b[off] through b[off+k-1] in the manner performed by System.arraycopy. The value k is added
* into pos and k is returned.
*
* This read method cannot block.
*
* @param b the buffer into which the data is read.
* @param off the start offset in the destination array b
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
* @exception NullPointerException If b is null.
* @exception IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
*/
@Override
public int read(byte b[], int off, int len) {
if (b == null) {
throw new NullPointerException();
} else if (off < 0 || len < 0 || len > b.length - off) {
throw new IndexOutOfBoundsException();
}
if (pos >= count) {
return -1;
}
int avail = count - pos;
if (len > avail) {
len = avail;
}
if (len <= 0) {
return 0;
}
System.arraycopy(buf, pos, b, off, len);
pos += len;
return len;
}
/**
* Skips n bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number k of bytes to be skipped is
* equal to the smaller of n and count-pos. The value k is added into pos and k is returned.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
*/
@Override
public long skip(long n) {
long k = count - pos;
if (n < k) {
k = n < 0 ? 0 : n;
}
pos += k;
return k;
}
/**
* Returns the number of remaining bytes that can be read (or skipped over) from this input stream.
*
* The value returned is count - pos, which is the number of bytes remaining to be read from the input buffer.
*
* @return the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.
*/
@Override
public int available() {
return count - pos;
}
/**
* Tests if this InputStream supports mark/reset. The markSupported method of ByteArrayInputStream always returns true.
*
* @since JDK1.1
*/
@Override
public boolean markSupported() {
return true;
}
/**
* Set the current marked position in the stream. ByteArrayInputStream objects are marked at position zero by default when constructed. They may be marked at another position within the buffer by
* this method.
*
* If no mark has been set, then the value of the mark is the offset passed to the constructor (or 0 if the offset was not supplied).
*
*
* Note: The readAheadLimit for this class has no meaning.
*
* @since JDK1.1
*/
@Override
public void mark(int readAheadLimit) {
mark = pos;
}
/**
* Resets the buffer to the marked position. The marked position is 0 unless another position was marked or an offset was specified in the constructor.
*/
@Override
public void reset() {
pos = mark;
}
/**
* Closing a ByteArrayInputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.
*
*/
@Override
public void close() {
}
}