我有一个InputStream，我正在从中读取字符。我希望多个读者访问此InputStream。似乎一种合理的方法是将传入的数据写入StringBuffer或StringBuilder，并让多个读者读取它。不幸的是，不推荐使用StringBufferInputStream。 StringReader读取一个字符串，而不是一个不断更新的可变对象。我有什么选择？写我自己的？
答案 0 :(得分：15)
注意： My other answer更为一般（在我看来更好）。
如@dimo414所述，以下答案要求第一位读者始终领先于第二位读者。如果确实是这种情况，那么这个答案可能仍然是可取的，因为它建立在标准类之上。
要创建两个独立于同一源读取的读取器，您必须确保它们不使用同一流中的数据。
这可以通过组合来自Apache Commons的TeeInputStream和PipedInputStream以及PipedOutputStream来实现，如下所示：
import java.io.*;
import org.apache.commons.io.input.TeeInputStream;
class Test {
public static void main(String[] args) throws IOException {
// Create the source input stream.
InputStream is = new FileInputStream("filename.txt");
// Create a piped input stream for one of the readers.
PipedInputStream in = new PipedInputStream();
// Create a tee-splitter for the other reader.
TeeInputStream tee = new TeeInputStream(is, new PipedOutputStream(in));
// Create the two buffered readers.
BufferedReader br1 = new BufferedReader(new InputStreamReader(tee));
BufferedReader br2 = new BufferedReader(new InputStreamReader(in));
// Do some interleaved reads from them.
System.out.println("One line from br1:");
System.out.println(br1.readLine());
System.out.println();
System.out.println("Two lines from br2:");
System.out.println(br2.readLine());
System.out.println(br2.readLine());
System.out.println();
System.out.println("One line from br1:");
System.out.println(br1.readLine());
System.out.println();
}
}
<强>输出：
One line from br1:
Line1: Lorem ipsum dolor sit amet, <-- reading from start
Two lines from br2:
Line1: Lorem ipsum dolor sit amet, <-- reading from start
Line2: consectetur adipisicing elit,
One line from br1:
Line2: consectetur adipisicing elit, <-- resumes on line 2
答案 1 :(得分：7)
正如您可能已经注意到的那样，一旦您从输入流中读取了一个字节，它就会永远消失（除非您自己将其保存在某个地方）。
下面的解决方案会保存字节，直到所有订阅输入流都已读取它。
它的工作原理如下：
// Create a SplittableInputStream from the originalStream
SplittableInputStream is = new SplittableInputStream(originalStream);
// Fork this to get more input streams reading independently from originalStream
SplittableInputStream is2 = is.split();
SplittableInputStream is3 = is.split();
每次is为split()时，它都会产生一个新的InputStream，它将从is被拆分的位置读取字节。
SplittableInputStream看起来如下（复制＆＃39; n＆＃39;粘贴！）：
class SplittableInputStream extends InputStream {
// Almost an input stream: The read-method takes an id.
static class MultiplexedSource {
static int MIN_BUF = 4096;
// Underlying source
private InputStream source;
// Read positions of each SplittableInputStream
private List<Integer> readPositions = new ArrayList<>();
// Data to be read by the SplittableInputStreams
int[] buffer = new int[MIN_BUF];
// Last valid position in buffer
int writePosition = 0;
public MultiplexedSource(InputStream source) {
this.source = source;
}
// Add a multiplexed reader. Return new reader id.
int addSource(int splitId) {
readPositions.add(splitId == -1 ? 0 : readPositions.get(splitId));
return readPositions.size() - 1;
}
// Make room for more data (and drop data that has been read by
// all readers)
private void readjustBuffer() {
int from = Collections.min(readPositions);
int to = Collections.max(readPositions);
int newLength = Math.max((to - from) * 2, MIN_BUF);
int[] newBuf = new int[newLength];
System.arraycopy(buffer, from, newBuf, 0, to - from);
for (int i = 0; i < readPositions.size(); i++)
readPositions.set(i, readPositions.get(i) - from);
writePosition -= from;
buffer = newBuf;
}
// Read and advance position for given reader
public int read(int readerId) throws IOException {
// Enough data in buffer?
if (readPositions.get(readerId) >= writePosition) {
readjustBuffer();
buffer[writePosition++] = source.read();
}
int pos = readPositions.get(readerId);
int b = buffer[pos];
if (b != -1)
readPositions.set(readerId, pos + 1);
return b;
}
}
// Non-root fields
MultiplexedSource multiSource;
int myId;
// Public constructor: Used for first SplittableInputStream
public SplittableInputStream(InputStream source) {
multiSource = new MultiplexedSource(source);
myId = multiSource.addSource(-1);
}
// Private constructor: Used in split()
private SplittableInputStream(MultiplexedSource multiSource, int splitId) {
this.multiSource = multiSource;
myId = multiSource.addSource(splitId);
}
// Returns a new InputStream that will read bytes from this position
// onwards.
public SplittableInputStream split() {
return new SplittableInputStream(multiSource, myId);
}
@Override
public int read() throws IOException {
return multiSource.read(myId);
}
}
最后，一个演示：
String str = "Lorem ipsum\ndolor sit\namet\n";
InputStream is = new ByteArrayInputStream(str.getBytes("UTF-8"));
// Create the two buffered readers.
SplittableInputStream is1 = new SplittableInputStream(is);
SplittableInputStream is2 = is1.split();
BufferedReader br1 = new BufferedReader(new InputStreamReader(is1));
BufferedReader br2 = new BufferedReader(new InputStreamReader(is2));
// Do some interleaved reads from them.
System.out.println("One line from br1:");
System.out.println(br1.readLine());
System.out.println();
System.out.println("Two lines from br2:");
System.out.println(br2.readLine());
System.out.println(br2.readLine());
System.out.println();
System.out.println("One line from br1:");
System.out.println(br1.readLine());
System.out.println();
<强>输出：
One line from br1:
Lorem ipsum
Two lines from br2:
Lorem ipsum
dolor sit
One line from br1:
dolor sit
答案 2 :(得分：5)
使用TeeInputStream将从InputStream读取的所有字节复制到辅助OutputStream，例如ByteArrayOutputStream。
答案 3 :(得分：4)
输入流的工作原理如下：一旦你从中读取了一部分，它就会永远消失。你不能回去重读它。你能做的就是这样：
class InputStreamSplitter {
InputStreamSplitter(InputStream toReadFrom) {
this.reader = new InputStreamReader(toReadFrom);
}
void addListener(Listener l) {
this.listeners.add(l);
}
void work() {
String line = this.reader.readLine();
while(line != null) {
for(Listener l : this.listeners) {
l.processLine(line);
}
}
}
}
interface Listener {
processLine(String line);
}
让所有感兴趣的各方实现Listener并将它们添加到InputStreamSplitter
答案 4 :(得分：2)
不使用StringWriter / StringBufferInputStream，而是将原始InputStream写入ByteArrayOutputStream。从原始InputStream读取完毕后，将ByteArrayOutputStream.toByteArray返回的字节数组传递给ByteArrayInputStream。使用此InputStream作为首选的InputStream，以传递需要从中读取的其他内容。
基本上，你在这里所做的就是将原始InputStream的内容存储到内存中的byte []缓存中，就像你最初尝试使用StringWriter / StringBufferInputStream一样。
答案 5 :(得分：1)
这是另一种独立读取两个流的方法，而不是假设一个先于另一个流，而是使用标准类。但是，它会在后台急切地从底层输入流中读取，这可能是不合需要的，具体取决于您的应用程序。
public static void main(String[] args) throws IOException {
// Create the source input stream.
InputStream is = new ByteArrayInputStream("line1\nline2\nline3".getBytes());
// Create a piped input stream for each reader;
PipedInputStream in1 = new PipedInputStream();
PipedInputStream in2 = new PipedInputStream();
// Start copying the input stream to both piped input streams.
startCopy(is, new TeeOutputStream(
new PipedOutputStream(in1), new PipedOutputStream(in2)));
// Create the two buffered readers.
BufferedReader br1 = new BufferedReader(new InputStreamReader(in1));
BufferedReader br2 = new BufferedReader(new InputStreamReader(in2));
// Do some interleaved reads from them.
// ...
}
private static void startCopy(InputStream in, OutputStream out) {
(new Thread() {
public void run() {
try {
IOUtils.copy(in, out);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}).start();
}
答案 6 :(得分：0)
Looking for a possible way to have an outputstream sending bytes to two or more different Inputstream, I found this forum. Unfortunately, the exact solution was directing to PipedOutputStream and PipedInputStream. So, I was declined to write a PipeOutputStream extension. Here it is. The example is written in the PipedOutputStream's "main" method.
/**
* Extensao de {@link PipedOutputStream}, onde eh possivel conectar mais de um {@link PipedInputStream}
*/
public class PipedOutputStreamEx extends PipedOutputStream {
/**
*
*/
public PipedOutputStreamEx() {
// TODO Auto-generated constructor stub
}
/* REMIND: identification of the read and write sides needs to be
more sophisticated. Either using thread groups (but what about
pipes within a thread?) or using finalization (but it may be a
long time until the next GC). */
private PipedInputStreamEx[] sinks=null;
public synchronized void connect(PipedInputStreamEx... pIns) throws IOException {
for (PipedInputStreamEx snk : pIns) {
if (snk == null) {
throw new NullPointerException();
} else if (sinks != null || snk.connected) {
throw new IOException("Already connected");
}
snk.in = -1;
snk.out = 0;
snk.connected = true;
}
this.sinks = pIns;
}
/**
* Writes the specified <code>byte</code> to the piped output stream.
* <p>
* Implements the <code>write</code> method of <code>OutputStream</code>.
*
* @param b the <code>byte</code> to be written.
* @exception IOException if the pipe is <a href=#BROKEN> broken</a>,
* {@link #connect(java.io.PipedInputStream) unconnected},
* closed, or if an I/O error occurs.
*/
public void write(int b) throws IOException {
if (this.sinks == null) {
throw new IOException("Pipe(s) not connected");
}
for (PipedInputStreamEx sink : this.sinks) {
sink.receive(b);
}
}
/**
* Writes <code>len</code> bytes from the specified byte array
* starting at offset <code>off</code> to this piped output stream.
* This method blocks until all the bytes are written to the output
* stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @exception IOException if the pipe is <a href=#BROKEN> broken</a>,
* {@link #connect(java.io.PipedInputStream) unconnected},
* closed, or if an I/O error occurs.
*/
public void write(byte b[], int off, int len) throws IOException {
if (sinks == null) {
throw new IOException("Pipe not connected");
} else if (b == null) {
throw new NullPointerException();
} else if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
for (PipedInputStreamEx sink : this.sinks) {
sink.receive(b, off, len);
}
}
/**
* Flushes this output stream and forces any buffered output bytes
* to be written out.
* This will notify any readers that bytes are waiting in the pipe.
*
* @exception IOException if an I/O error occurs.
*/
public synchronized void flush() throws IOException {
if (sinks != null) {
for (PipedInputStreamEx sink : this.sinks) {
synchronized (sink) {
sink.notifyAll();
}
}
}
}
/**
* Closes this piped output stream and releases any system resources
* associated with this stream. This stream may no longer be used for
* writing bytes.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
if (sinks != null) {
for (PipedInputStreamEx sink : this.sinks) {
sink.receivedLast();
}
}
}
/**
* Teste desta extensao de {@link PipedOutputStream}
* @param args
* @throws InterruptedException
* @throws IOException
*/
public static void main(String[] args) throws InterruptedException, IOException {
final PipedOutputStreamEx pOut = new PipedOutputStreamEx();
final PipedInputStreamEx pInHash = new PipedInputStreamEx();
final PipedInputStreamEx pInConsole = new PipedInputStreamEx();
pOut.connect(pInHash, pInConsole);
Thread escreve = new Thread("Escrevendo") {
@Override
public void run() {
String[] paraGravar = new String[]{
"linha1 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha2 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha3 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha4 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha5 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha6 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha7 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha8 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha9 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha10 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha11 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha12 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha13 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha14 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha15 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha16 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha17 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha18 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha19 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
, "linha20 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789\n"
};
for (String s :paraGravar) {
try {
pOut.write(s.getBytes("ISO-8859-1") );
Thread.sleep(100);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
try {
pOut.close();
} catch (IOException e) {
e.printStackTrace();
}
}
};
Thread le1 = new Thread("Le1 - hash") {
@Override
public void run() {
try {
System.out.println("HASH: "+HashUtil.getHashCRC(pInHash,true));
} catch (Exception e) {
e.printStackTrace();
}
}
};
Thread le2 = new Thread("Le2 - escreve no console") {
@Override
public void run() {
BufferedReader bIn = new BufferedReader(new InputStreamReader(pInConsole));
String s;
try {
while ( (s=bIn.readLine())!=null) {
Thread.sleep(700); //teste simulando o um leitor lento...
System.out.println(s);
}
} catch (IOException e) {
throw new RuntimeException(e);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
escreve.start();
le1.start();
le2.start();
escreve.join();
le1.join();
le2.join();
pInHash.close();
pInConsole.close();
}
}
Here is the PipedInputStreamEx code. Unfortunately, I had to copy all JDK code, to have access to "connected", "in" and "out" properties.
/**
* Extensao de {@link PipedInputStream}, que permite conetar mais de um destes no {@link PipedOutputStream}
* Como a classe ancestral possui propriedades 'package friend', tivemos que copiar o codigo herdado :/
*/
public class PipedInputStreamEx extends PipedInputStream {
@Override
public void connect(PipedOutputStream src) throws IOException {
throw new IOException("conecte usando PipedOutputStream.connect()");
}
//----------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------
//--------- INICIO codigo da classe herdada (alguns metodos comentados...)----------------------------------
//----------------------------------------------------------------------------------------------------------
boolean closedByWriter = false;
volatile boolean closedByReader = false;
boolean connected = false;
/* REMIND: identification of the read and write sides needs to be
more sophisticated. Either using thread groups (but what about
pipes within a thread?) or using finalization (but it may be a
long time until the next GC). */
Thread readSide;
Thread writeSide;
private static final int DEFAULT_PIPE_SIZE = 1024;
/**
* The default size of the pipe's circular input buffer.
* @since JDK1.1
*/
// This used to be a constant before the pipe size was allowed
// to change. This field will continue to be maintained
// for backward compatibility.
protected static final int PIPE_SIZE = DEFAULT_PIPE_SIZE;
/**
* The circular buffer into which incoming data is placed.
* @since JDK1.1
*/
protected byte buffer[];
/**
* The index of the position in the circular buffer at which the
* next byte of data will be stored when received from the connected
* piped output stream. <code>in<0</code> implies the buffer is empty,
* <code>in==out</code> implies the buffer is full
* @since JDK1.1
*/
protected int in = -1;
/**
* The index of the position in the circular buffer at which the next
* byte of data will be read by this piped input stream.
* @since JDK1.1
*/
protected int out = 0;
// /**
// * Creates a <code>PipedInputStream</code> so
// * that it is connected to the piped output
// * stream <code>src</code>. Data bytes written
// * to <code>src</code> will then be available
// * as input from this stream.
// *
// * @param src the stream to connect to.
// * @exception IOException if an I/O error occurs.
// */
// public PipedInputStream(PipedOutputStream src) throws IOException {
// this(src, DEFAULT_PIPE_SIZE);
// }
//
// /**
// * Creates a <code>PipedInputStream</code> so that it is
// * connected to the piped output stream
// * <code>src</code> and uses the specified pipe size for
// * the pipe's buffer.
// * Data bytes written to <code>src</code> will then
// * be available as input from this stream.
// *
// * @param src the stream to connect to.
// * @param pipeSize the size of the pipe's buffer.
// * @exception IOException if an I/O error occurs.
// * @exception IllegalArgumentException if <code>pipeSize <= 0</code>.
// * @since 1.6
// */
// public PipedInputStream(PipedOutputStream src, int pipeSize)
// throws IOException {
// initPipe(pipeSize);
// connect(src);
// }
/**
* Creates a <code>PipedInputStream</code> so
* that it is not yet {@linkplain #connect(java.io.PipedOutputStream)
* connected}.
* It must be {@linkplain java.io.PipedOutputStream#connect(
* java.io.PipedInputStream) connected} to a
* <code>PipedOutputStream</code> before being used.
*/
public PipedInputStreamEx() {
initPipe(DEFAULT_PIPE_SIZE);
}
/**
* Creates a <code>PipedInputStream</code> so that it is not yet
* {@linkplain #connect(java.io.PipedOutputStream) connected} and
* uses the specified pipe size for the pipe's buffer.
* It must be {@linkplain java.io.PipedOutputStream#connect(
* java.io.PipedInputStream)
* connected} to a <code>PipedOutputStream</code> before being used.
*
* @param pipeSize the size of the pipe's buffer.
* @exception IllegalArgumentException if <code>pipeSize <= 0</code>.
* @since 1.6
*/
public PipedInputStreamEx(int pipeSize) {
initPipe(pipeSize);
}
private void initPipe(int pipeSize) {
if (pipeSize <= 0) {
throw new IllegalArgumentException("Pipe Size <= 0");
}
buffer = new byte[pipeSize];
}
// /**
// * Causes this piped input stream to be connected
// * to the piped output stream <code>src</code>.
// * If this object is already connected to some
// * other piped output stream, an <code>IOException</code>
// * is thrown.
// * <p>
// * If <code>src</code> is an
// * unconnected piped output stream and <code>snk</code>
// * is an unconnected piped input stream, they
// * may be connected by either the call:
// * <p>
// * <pre><code>snk.connect(src)</code> </pre>
// * <p>
// * or the call:
// * <p>
// * <pre><code>src.connect(snk)</code> </pre>
// * <p>
// * The two
// * calls have the same effect.
// *
// * @param src The piped output stream to connect to.
// * @exception IOException if an I/O error occurs.
// */
// public void connect(PipedOutputStream src) throws IOException {
// src.connect(this);
// }
/**
* Receives a byte of data. This method will block if no input is
* available.
* @param b the byte being received
* @exception IOException If the pipe is <a href=#BROKEN> <code>broken</code></a>,
* {@link #connect(java.io.PipedOutputStream) unconnected},
* closed, or if an I/O error occurs.
* @since JDK1.1
*/
protected synchronized void receive(int b) throws IOException {
checkStateForReceive();
writeSide = Thread.currentThread();
if (in == out)
awaitSpace();
if (in < 0) {
in = 0;
out = 0;
}
buffer[in++] = (byte)(b & 0xFF);
if (in >= buffer.length) {
in = 0;
}
}
/**
* Receives data into an array of bytes. This method will
* block until some input is available.
* @param b the buffer into which the data is received
* @param off the start offset of the data
* @param len the maximum number of bytes received
* @exception IOException If the pipe is <a href=#BROKEN> broken</a>,
* {@link #connect(java.io.PipedOutputStream) unconnected},
* closed,or if an I/O error occurs.
*/
synchronized void receive(byte b[], int off, int len) throws IOException {
checkStateForReceive();
writeSide = Thread.currentThread();
int bytesToTransfer = len;
while (bytesToTransfer > 0) {
if (in == out)
awaitSpace();
int nextTransferAmount = 0;
if (out < in) {
nextTransferAmount = buffer.length - in;
} else if (in < out) {
if (in == -1) {
in = out = 0;
nextTransferAmount = buffer.length - in;
} else {
nextTransferAmount = out - in;
}
}
if (nextTransferAmount > bytesToTransfer)
nextTransferAmount = bytesToTransfer;
assert(nextTransferAmount > 0);
System.arraycopy(b, off, buffer, in, nextTransferAmount);
bytesToTransfer -= nextTransferAmount;
off += nextTransferAmount;
in += nextTransferAmount;
if (in >= buffer.length) {
in = 0;
}
}
}
private void checkStateForReceive() throws IOException {
if (!connected) {
throw new IOException("Pipe not connected");
} else if (closedByWriter || closedByReader) {
throw new IOException("Pipe closed");
} else if (readSide != null && !readSide.isAlive()) {
throw new IOException("Read end dead");
}
}
private void awaitSpace() throws IOException {
while (in == out) {
checkStateForReceive();
/* full: kick any waiting readers */
notifyAll();
try {
wait(1000);
} catch (InterruptedException ex) {
throw new java.io.InterruptedIOException();
}
}
}
/**
* Notifies all waiting threads that the last byte of data has been
* received.
*/
synchronized void receivedLast() {
closedByWriter = true;
notifyAll();
}
/**
* Reads the next byte of data from this piped input stream. The
* value byte is returned as an <code>int</code> in the range
* <code>0</code> to <code>255</code>.
* This method blocks until input data is available, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @exception IOException if the pipe is
* {@link #connect(java.io.PipedOutputStream) unconnected},
* <a href=#BROKEN> <code>broken</code></a>, closed,
* or if an I/O error occurs.
*/
public synchronized int read() throws IOException {
if (!connected) {
throw new IOException("Pipe not connected");
} else if (closedByReader) {
throw new IOException("Pipe closed");
} else if (writeSide != null && !writeSide.isAlive()
&& !closedByWriter && (in < 0)) {
throw new IOException("Write end dead");
}
readSide = Thread.currentThread();
int trials = 2;
while (in < 0) {
if (closedByWriter) {
/* closed by writer, return EOF */
return -1;
}
if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) {
throw new IOException("Pipe broken");
}
/* might be a writer waiting */
notifyAll();
try {
wait(1000);
} catch (InterruptedException ex) {
throw new java.io.InterruptedIOException();
}
}
int ret = buffer[out++] & 0xFF;
if (out >= buffer.length) {
out = 0;
}
if (in == out) {
/* now empty */
in = -1;
}
return ret;
}
/**
* Reads up to <code>len</code> bytes of data from this piped input
* stream into an array of bytes. Less than <code>len</code> bytes
* will be read if the end of the data stream is reached or if
* <code>len</code> exceeds the pipe's buffer size.
* If <code>len </code> is zero, then no bytes are read and 0 is returned;
* otherwise, the method blocks until at least 1 byte of input is
* available, end of the stream has been detected, or an exception is
* thrown.
*
* @param b the buffer into which the data is read.
* @param off the start offset in the destination array <code>b</code>
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end of
* the stream has been reached.
* @exception NullPointerException If <code>b</code> is <code>null</code>.
* @exception IndexOutOfBoundsException If <code>off</code> is negative,
* <code>len</code> is negative, or <code>len</code> is greater than
* <code>b.length - off</code>
* @exception IOException if the pipe is <a href=#BROKEN> <code>broken</code></a>,
* {@link #connect(java.io.PipedOutputStream) unconnected},
* closed, or if an I/O error occurs.
*/
public synchronized int read(byte b[], int off, int len) throws IOException {
if (b == null) {
throw new NullPointerException();
} else if (off < 0 || len < 0 || len > b.length - off) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
/* possibly wait on the first character */
int c = read();
if (c < 0) {
return -1;
}
b[off] = (byte) c;
int rlen = 1;
while ((in >= 0) && (len > 1)) {
int available;
if (in > out) {
available = Math.min((buffer.length - out), (in - out));
} else {
available = buffer.length - out;
}
// A byte is read beforehand outside the loop
if (available > (len - 1)) {
available = len - 1;
}
System.arraycopy(buffer, out, b, off + rlen, available);
out += available;
rlen += available;
len -= available;
if (out >= buffer.length) {
out = 0;
}
if (in == out) {
/* now empty */
in = -1;
}
}
return rlen;
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking.
*
* @return the number of bytes that can be read from this input stream
* without blocking, or {@code 0} if this input stream has been
* closed by invoking its {@link #close()} method, or if the pipe
* is {@link #connect(java.io.PipedOutputStream) unconnected}, or
* <a href=#BROKEN> <code>broken</code></a>.
*
* @exception IOException if an I/O error occurs.
* @since JDK1.0.2
*/
public synchronized int available() throws IOException {
if(in < 0)
return 0;
else if(in == out)
return buffer.length;
else if (in > out)
return in - out;
else
return in + buffer.length - out;
}
/**
* Closes this piped input stream and releases any system resources
* associated with the stream.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
closedByReader = true;
synchronized (this) {
in = -1;
}
}
//----------------------------------------------------------------------------------------------------------
//--------- FIM codigo da classe herdada -------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------
}