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4358774: Add null InputStream and OutputStream

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Reviewed-by: alanb, prappo, reinhapa, rriggs
This commit is contained in:
Brian Burkhalter 2018-01-12 11:06:24 -08:00
parent 473e36a9f3
commit 49beab63c8
6 changed files with 454 additions and 9 deletions
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91
src/java.base/share/classes/java/io/InputStream.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -55,6 +55,93 @@ public abstract class InputStream implements Closeable {
private static final int DEFAULT_BUFFER_SIZE = 8192;
/**
* Returns a new {@code InputStream} that reads no bytes. The returned
* stream is initially open. The stream is closed by calling the
* {@code close()} method. Subsequent calls to {@code close()} have no
* effect.
*
* <p> While the stream is open, the {@code available()}, {@code read()},
* {@code read(byte[])}, {@code read(byte[], int, int)},
* {@code readAllBytes()}, {@code readNBytes()}, {@code skip()}, and
* {@code transferTo()} methods all behave as if end of stream has been
* reached. After the stream has been closed, these methods all throw
* {@code IOException}.
*
* <p> The {@code markSupported()} method returns {@code false}. The
* {@code mark()} method does nothing, and the {@code reset()} method
* throws {@code IOException}.
*
* @return an {@code InputStream} which contains no bytes
*
* @since 11
*/
public static InputStream nullInputStream() {
return new InputStream() {
private volatile boolean closed;
private void ensureOpen() throws IOException {
if (closed) {
throw new IOException("Stream closed");
}
}
@Override
public int available () throws IOException {
ensureOpen();
return 0;
}
@Override
public int read() throws IOException {
ensureOpen();
return -1;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
Objects.checkFromIndexSize(off, len, b.length);
if (len == 0) {
return 0;
}
ensureOpen();
return -1;
}
@Override
public byte[] readAllBytes() throws IOException {
ensureOpen();
return new byte[0];
}
@Override
public int readNBytes(byte[] b, int off, int len)
throws IOException {
Objects.checkFromIndexSize(off, len, b.length);
ensureOpen();
return 0;
}
@Override
public long skip(long n) throws IOException {
ensureOpen();
return 0L;
}
@Override
public long transferTo(OutputStream out) throws IOException {
Objects.requireNonNull(out);
ensureOpen();
return 0L;
}
@Override
public void close() throws IOException {
closed = true;
}
};
}
/**
* Reads the next byte of data from the input stream. The value byte is
* returned as an <code>int</code> in the range <code>0</code> to
@ -166,7 +253,6 @@ public abstract class InputStream implements Closeable {
* @see java.io.InputStream#read()
*/
public int read(byte b[], int off, int len) throws IOException {
Objects.requireNonNull(b);
Objects.checkFromIndexSize(off, len, b.length);
if (len == 0) {
return 0;
@ -326,7 +412,6 @@ public abstract class InputStream implements Closeable {
* @since 9
*/
public int readNBytes(byte[] b, int off, int len) throws IOException {
Objects.requireNonNull(b);
Objects.checkFromIndexSize(off, len, b.length);
int n = 0;

48
src/java.base/share/classes/java/io/OutputStream.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -46,6 +46,51 @@ import java.util.Objects;
* @since 1.0
*/
public abstract class OutputStream implements Closeable, Flushable {
/**
* Returns a new {@code OutputStream} which discards all bytes. The
* returned stream is initially open. The stream is closed by calling
* the {@code close()} method. Subsequent calls to {@code close()} have
* no effect.
*
* <p> While the stream is open, the {@code write(int)}, {@code
* write(byte[])}, and {@code write(byte[], int, int)} methods do nothing.
* After the stream has been closed, these methods all throw {@code
* IOException}.
*
* <p> The {@code flush()} method does nothing.
*
* @return an {@code OutputStream} which discards all bytes
*
* @since 11
*/
public static OutputStream nullOutputStream() {
return new OutputStream() {
private volatile boolean closed;
private void ensureOpen() throws IOException {
if (closed) {
throw new IOException("Stream closed");
}
}
@Override
public void write(int b) throws IOException {
ensureOpen();
}
@Override
public void write(byte b[], int off, int len) throws IOException {
Objects.checkFromIndexSize(off, len, b.length);
ensureOpen();
}
@Override
public void close() {
closed = true;
}
};
}
/**
* Writes the specified byte to this output stream. The general
* contract for <code>write</code> is that one byte is written
@ -106,7 +151,6 @@ public abstract class OutputStream implements Closeable, Flushable {
* stream is closed.
*/
public void write(byte b[], int off, int len) throws IOException {
Objects.requireNonNull(b);
Objects.checkFromIndexSize(off, len, b.length);
// len == 0 condition implicitly handled by loop bounds
for (int i = 0 ; i < len ; i++) {