169 lines
5.3 KiB
Java
169 lines
5.3 KiB
Java
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package org.warp.commonutils.stream;
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import java.io.Closeable;
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import java.io.Flushable;
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import java.io.OutputStream;
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import java.util.Objects;
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/**
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* This abstract class is the superclass of all classes representing
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* an output stream of bytes. An output stream accepts output bytes
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* and sends them to some sink.
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* <p>
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* Applications that need to define a subclass of
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* {@code OutputStream} must always provide at least a method
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* that writes one byte of output.
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*
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* @author Arthur van Hoff
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* @see java.io.BufferedOutputStream
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* @see java.io.ByteArrayOutputStream
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* @see java.io.DataOutputStream
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* @see java.io.FilterOutputStream
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* @see java.io.InputStream
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* @see java.io.OutputStream#write(int)
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* @since 1.0
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*/
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public abstract class SafeOutputStream extends OutputStream implements Closeable, Flushable {
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/**
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* Constructor for subclasses to call.
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*/
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public SafeOutputStream() {}
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/**
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* Returns a new {@code OutputStream} which discards all bytes. The
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* returned stream is initially open. The stream is closed by calling
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* the {@code close()} method. Subsequent calls to {@code close()} have
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* no effect.
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*
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* <p> While the stream is open, the {@code write(int)}, {@code
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* write(byte[])}, and {@code write(byte[], int, int)} methods do nothing.
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* After the stream has been closed, these methods all throw {@code
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* IOException}.
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*
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* <p> The {@code flush()} method does nothing.
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*
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* @return an {@code OutputStream} which discards all bytes
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*
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* @since 11
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*/
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public static java.io.OutputStream nullOutputStream() {
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return new java.io.OutputStream() {
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private volatile boolean closed;
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private void ensureOpen() {
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if (closed) {
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throw new IllegalStateException("Stream closed");
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}
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}
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@Override
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public void write(int b) {
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ensureOpen();
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}
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@Override
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public void write(byte b[], int off, int len) {
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Objects.checkFromIndexSize(off, len, b.length);
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ensureOpen();
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}
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@Override
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public void close() {
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closed = true;
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}
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};
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}
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/**
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* Writes the specified byte to this output stream. The general
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* contract for {@code write} is that one byte is written
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* to the output stream. The byte to be written is the eight
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* low-order bits of the argument {@code b}. The 24
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* high-order bits of {@code b} are ignored.
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* <p>
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* Subclasses of {@code OutputStream} must provide an
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* implementation for this method.
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*
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* @param b the {@code byte}.
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*/
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public abstract void write(int b);
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/**
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* Writes {@code b.length} bytes from the specified byte array
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* to this output stream. The general contract for {@code write(b)}
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* is that it should have exactly the same effect as the call
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* {@code write(b, 0, b.length)}.
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*
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* @param b the data.
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* @see java.io.OutputStream#write(byte[], int, int)
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*/
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public void write(byte b[]) {
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write(b, 0, b.length);
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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 output stream.
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* The general contract for {@code write(b, off, len)} is that
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* some of the bytes in the array {@code b} are written to the
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* output stream in order; element {@code b[off]} is the first
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* byte written and {@code b[off+len-1]} is the last byte written
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* by this operation.
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* <p>
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* The {@code write} method of {@code OutputStream} calls
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* the write method of one argument on each of the bytes to be
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* written out. Subclasses are encouraged to override this method and
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* provide a more efficient implementation.
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* <p>
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* If {@code b} is {@code null}, a
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* {@code NullPointerException} is thrown.
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* <p>
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* If {@code off} is negative, or {@code len} is negative, or
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* {@code off+len} is greater than the length of the array
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* {@code b}, then an {@code IndexOutOfBoundsException} is thrown.
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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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*/
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public void write(byte b[], int off, int len) {
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Objects.checkFromIndexSize(off, len, b.length);
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// len == 0 condition implicitly handled by loop bounds
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for (int i = 0 ; i < len ; i++) {
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write(b[off + i]);
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}
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}
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/**
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* Flushes this output stream and forces any buffered output bytes
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* to be written out. The general contract of {@code flush} is
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* that calling it is an indication that, if any bytes previously
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* written have been buffered by the implementation of the output
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* stream, such bytes should immediately be written to their
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* intended destination.
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* <p>
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* If the intended destination of this stream is an abstraction provided by
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* the underlying operating system, for example a file, then flushing the
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* stream guarantees only that bytes previously written to the stream are
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* passed to the operating system for writing; it does not guarantee that
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* they are actually written to a physical device such as a disk drive.
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* <p>
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* The {@code flush} method of {@code OutputStream} does nothing.
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*
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*/
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public void flush() {
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}
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/**
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* Closes this output stream and releases any system resources
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* associated with this stream. The general contract of {@code close}
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* is that it closes the output stream. A closed stream cannot perform
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* output operations and cannot be reopened.
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* <p>
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* The {@code close} method of {@code OutputStream} does nothing.
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*
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*/
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public void close() {
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}
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}
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