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SunSPOT API V4.0 |
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java.lang.Object java.io.OutputStream com.sun.spot.util.CrcOutputStream
public class CrcOutputStream
CrcOutputStream provides CRC checking and flow control for two Java programs
communicating with two input and output stream pairs.
To use this class, open a CrcOutputStream around the InputStream and OutputStream at each end.
Then use the accessor getInputStream()
to obtain an InputStream and do further io using
the CrcOutputStream and the InputStream obtained from getInputStream()
. Data is sent over
the output stream in blocks whose size can be specified in CrcOutputStream constructor. A smaller
block is sent whenever a flush is done on the CrcOutputStream.
If data corruption occurs, IOExceptions will be thrown on both the sending and receiving threads.
Subsequent read and writes will still be valid.
The streams are not thread-safe in the presence of multiple simultaneous accessors; each stream should be
accessed from one thread.
Constructor Summary | |
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CrcOutputStream(OutputStream outputStream,
InputStream inputStream)
Open an output stream that will add CRC checking and flow control to the outgoing data stream. |
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CrcOutputStream(OutputStream outputStream,
InputStream inputStream,
int blockSize)
Open an output stream that will add CRC checking and flow control to the outgoing data stream. |
Method Summary | |
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void |
close()
Closes this output stream and releases any system resources associated with this stream. |
void |
flush()
Flushes this output stream and forces any buffered output bytes to be written out. |
InputStream |
getInputStream()
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boolean |
probe()
Returns true if there's a CrcOutputStream at the far end, and someone there is waiting on a read. |
void |
write(byte[] b,
int off,
int len)
Writes len bytes from the specified byte array
starting at offset off to this output stream. |
void |
write(int b)
Writes the specified byte to this output stream. |
Methods inherited from class java.io.OutputStream |
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write |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public CrcOutputStream(OutputStream outputStream, InputStream inputStream)
outputStream
- the underlying output stream on which to write data.inputStream
- to receive data from the remote CRCOutputStream, and acknowledgements and CRC
hashes from the remote CRC InputStream.public CrcOutputStream(OutputStream outputStream, InputStream inputStream, int blockSize)
outputStream
- the underlying output stream on which to write data.inputStream
- to receive data from the remote CRCOutputStream, and acknowledgements and CRC
hashes from the remote CRC InputStream.blockSize
- the maximum number of bytes of data to be written before waiting for a CRC confirmation
from the remote device. Also, the remote device will never buffer more than (2 * blockSize) bytes
of data awaiting reading from the containing CRC InputStream.Method Detail |
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public InputStream getInputStream()
public void write(int b) throws IOException
OutputStream
write
is that one byte is written
to the output stream. The byte to be written is the eight
low-order bits of the argument b
. The 24
high-order bits of b
are ignored.
Subclasses of OutputStream
must provide an
implementation for this method.
write
in class OutputStream
b
- the byte
.
IOException
- if an I/O error occurs. In particular,
an IOException
may be thrown if the
output stream has been closed.OutputStream.write(int)
public void write(byte[] b, int off, int len) throws IOException
OutputStream
len
bytes from the specified byte array
starting at offset off
to this output stream.
The general contract for write(b, off, len)
is that
some of the bytes in the array b
are written to the
output stream in order; element b[off]
is the first
byte written and b[off+len-1]
is the last byte written
by this operation.
The write
method of OutputStream
calls
the write method of one argument on each of the bytes to be
written out. Subclasses are encouraged to override this method and
provide a more efficient implementation.
If b
is null
, a
NullPointerException
is thrown.
If off
is negative, or len
is negative, or
off+len
is greater than the length of the array
b
, then an IndexOutOfBoundsException is thrown.
write
in class OutputStream
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.
IOException
- if an I/O error occurs. In particular,
an IOException
is thrown if the output
stream is closed.OutputStream.write(byte[], int, int)
public void flush() throws IOException
OutputStream
flush
is
that calling it is an indication that, if any bytes previously
written have been buffered by the implementation of the output
stream, such bytes should immediately be written to their
intended destination.
The flush
method of OutputStream
does nothing.
flush
in class OutputStream
IOException
- if an I/O error occurs.OutputStream.flush()
public void close() throws IOException
OutputStream
close
is that it closes the output stream. A closed stream cannot perform
output operations and cannot be reopened.
The close
method of OutputStream
does nothing.
close
in class OutputStream
IOException
- if an I/O error occurs.OutputStream.close()
public boolean probe() throws IOException
IOException
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SunSPOT API V4.0 |
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