libcore.io.Streams Maven / Gradle / Ivy
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed 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 libcore.io;
import java.io.ByteArrayOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringWriter;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicReference;
public final class Streams {
private static AtomicReference skipBuffer = new AtomicReference();
private Streams() {}
/**
* Implements InputStream.read(int) in terms of InputStream.read(byte[], int, int).
* InputStream assumes that you implement InputStream.read(int) and provides default
* implementations of the others, but often the opposite is more efficient.
*/
public static int readSingleByte(InputStream in) throws IOException {
byte[] buffer = new byte[1];
int result = in.read(buffer, 0, 1);
return (result != -1) ? buffer[0] & 0xff : -1;
}
/**
* Implements OutputStream.write(int) in terms of OutputStream.write(byte[], int, int).
* OutputStream assumes that you implement OutputStream.write(int) and provides default
* implementations of the others, but often the opposite is more efficient.
*/
public static void writeSingleByte(OutputStream out, int b) throws IOException {
byte[] buffer = new byte[1];
buffer[0] = (byte) (b & 0xff);
out.write(buffer);
}
/**
* Fills 'dst' with bytes from 'in', throwing EOFException if insufficient bytes are available.
*/
public static void readFully(InputStream in, byte[] dst) throws IOException {
readFully(in, dst, 0, dst.length);
}
/**
* Reads exactly 'byteCount' bytes from 'in' (into 'dst' at offset 'offset'), and throws
* EOFException if insufficient bytes are available.
*
* Used to implement {@link java.io.DataInputStream#readFully(byte[], int, int)}.
*/
public static void readFully(InputStream in, byte[] dst, int offset, int byteCount) throws IOException {
if (byteCount == 0) {
return;
}
if (in == null) {
throw new NullPointerException("in == null");
}
if (dst == null) {
throw new NullPointerException("dst == null");
}
Arrays.checkOffsetAndCount(dst.length, offset, byteCount);
while (byteCount > 0) {
int bytesRead = in.read(dst, offset, byteCount);
if (bytesRead < 0) {
throw new EOFException();
}
offset += bytesRead;
byteCount -= bytesRead;
}
}
/**
* Returns a byte[] containing the remainder of 'in', closing it when done.
*/
public static byte[] readFully(InputStream in) throws IOException {
try {
return readFullyNoClose(in);
} finally {
in.close();
}
}
/**
* Returns a byte[] containing the remainder of 'in'.
*/
public static byte[] readFullyNoClose(InputStream in) throws IOException {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int count;
while ((count = in.read(buffer)) != -1) {
bytes.write(buffer, 0, count);
}
return bytes.toByteArray();
}
/**
* Returns the remainder of 'reader' as a string, closing it when done.
*/
public static String readFully(Reader reader) throws IOException {
try {
StringWriter writer = new StringWriter();
char[] buffer = new char[1024];
int count;
while ((count = reader.read(buffer)) != -1) {
writer.write(buffer, 0, count);
}
return writer.toString();
} finally {
reader.close();
}
}
public static void skipAll(InputStream in) throws IOException {
do {
in.skip(Long.MAX_VALUE);
} while (in.read() != -1);
}
/**
* Call {@code in.read()} repeatedly until either the stream is exhausted or
* {@code byteCount} bytes have been read.
*
* This method reuses the skip buffer but is careful to never use it at
* the same time that another stream is using it. Otherwise streams that use
* the caller's buffer for consistency checks like CRC could be clobbered by
* other threads. A thread-local buffer is also insufficient because some
* streams may call other streams in their skip() method, also clobbering the
* buffer.
*/
public static long skipByReading(InputStream in, long byteCount) throws IOException {
// acquire the shared skip buffer.
byte[] buffer = skipBuffer.getAndSet(null);
if (buffer == null) {
buffer = new byte[4096];
}
long skipped = 0;
while (skipped < byteCount) {
int toRead = (int) Math.min(byteCount - skipped, buffer.length);
int read = in.read(buffer, 0, toRead);
if (read == -1) {
break;
}
skipped += read;
if (read < toRead) {
break;
}
}
// release the shared skip buffer.
skipBuffer.set(buffer);
return skipped;
}
/**
* Copies all of the bytes from {@code in} to {@code out}. Neither stream is closed.
* Returns the total number of bytes transferred.
*/
public static int copy(InputStream in, OutputStream out) throws IOException {
int total = 0;
byte[] buffer = new byte[8192];
int c;
while ((c = in.read(buffer)) != -1) {
total += c;
out.write(buffer, 0, c);
}
return total;
}
/**
* Returns the ASCII characters up to but not including the next "\r\n", or
* "\n".
*
* @throws java.io.EOFException if the stream is exhausted before the next newline
* character.
*/
public static String readAsciiLine(InputStream in) throws IOException {
// TODO: support UTF-8 here instead
StringBuilder result = new StringBuilder(80);
while (true) {
int c = in.read();
if (c == -1) {
throw new EOFException();
} else if (c == '\n') {
break;
}
result.append((char) c);
}
int length = result.length();
if (length > 0 && result.charAt(length - 1) == '\r') {
result.setLength(length - 1);
}
return result.toString();
}
}