java.io.InputStream
com.sun.squawk.io.j2me.channel.ChannelInputStream
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java.lang.Object
public class ChannelInputStream
ChannelInputStream
| Constructor Summary | |
|---|---|
ChannelInputStream(Protocol parent)
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| Method Summary | |
|---|---|
int |
available()
Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. |
void |
close()
Closes this input stream and releases any system resources associated with the stream. |
void |
mark(int readlimit)
Marks the current position in this input stream. |
boolean |
markSupported()
Tests if this input stream supports the mark and
reset methods. |
int |
read()
Reads the next byte of data from the input stream. |
int |
read(byte[] b,
int off,
int len)
Reads up to len bytes of data from the input stream into
an array of bytes. |
boolean |
readBoolean()
Reads one input byte and returns true if that byte is nonzero,
false if that byte is zero. |
byte |
readByte()
Reads and returns one input byte. |
char |
readChar()
See the general contract of the readChar
method of DataInput. |
double |
readDouble()
Reads a 64 bit double. |
float |
readFloat()
Reads a 32 bit float. |
void |
readFully(byte[] b)
Reads some bytes from an input stream and stores them into the buffer array b. |
void |
readFully(byte[] b,
int off,
int len)
See the general contract of the readFully
method of DataInput. |
int |
readInt()
Reads four input bytes and returns an int value. |
long |
readLong()
Reads eight input bytes and returns a long value. |
short |
readShort()
Reads two input bytes and returns a short value. |
int |
readUnsignedByte()
Reads one input byte, zero-extends it to type int, and returns
the result, which is therefore in the range
0
through 255. |
int |
readUnsignedShort()
Reads two input bytes, zero-extends it to type int, and returns
an int value in the range 0
through 65535. |
String |
readUTF()
Reads in a string that has been encoded using a modified UTF-8 format. |
void |
reset()
Repositions this stream to the position at the time the mark method was last called on this input stream. |
long |
skip(long n)
Skips over and discards n bytes of data from this input
stream. |
int |
skipBytes(int n)
Makes an attempt to skip over n bytes
of data from the input
stream, discarding the skipped bytes. |
| Methods inherited from class java.io.InputStream |
|---|
read |
| Methods inherited from class java.lang.Object |
|---|
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public ChannelInputStream(Protocol parent)
throws IOException
IOException| Method Detail |
|---|
public void close()
throws IOException
InputStream The close method of InputStream does
nothing.
close in class InputStreamIOException - if an I/O error occurs.
public int read()
throws IOException
InputStreamint in the range 0 to
255. If no byte is available because the end of the stream
has been reached, the value -1 is returned. This method
blocks until input data is available, the end of the stream is detected,
or an exception is thrown.
A subclass must provide an implementation of this method.
read in class InputStream-1 if the end of the
stream is reached.
IOException - if an I/O error occurs.
public int readUnsignedShort()
throws IOException
DataInputint, and returns
an int value in the range 0
through 65535. Let a
be the first byte read and
b
be the second byte. The value returned is:
(((a & 0xff) << 8) | (b & 0xff))
writeShort method
of interface DataOutput if
the argument to writeShort
was intended to be a value in the range
0 through 65535.
readUnsignedShort in interface DataInputEOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public int readInt()
throws IOException
DataInputint value. Let a
be the first byte read, b be
the second byte, c be the third
byte, and d be the fourth
byte. The value returned is:
(((a & 0xff) << 24) | ((b & 0xff) << 16) |
((c & 0xff) << 8) | (d & 0xff))
This method is suitable
for reading bytes written by the writeInt
method of interface DataOutput.
readInt in interface DataInputint value read.
EOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public long readLong()
throws IOException
DataInputlong value. Let a
be the first byte read, b be
the second byte, c be the third
byte, d be the fourth byte,
e be the fifth byte, f
be the sixth byte, g be the
seventh byte, and h be the
eighth byte. The value returned is:
(((long)(a & 0xff) << 56) |
((long)(b & 0xff) << 48) |
((long)(c & 0xff) << 40) |
((long)(d & 0xff) << 32) |
((long)(e & 0xff) << 24) |
((long)(f & 0xff) << 16) |
((long)(g & 0xff) << 8) |
((long)(h & 0xff)))
This method is suitable
for reading bytes written by the writeLong
method of interface DataOutput.
readLong in interface DataInputlong value read.
EOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public int read(byte[] b,
int off,
int len)
throws IOException
InputStreamlen bytes of data from the input stream into
an array of bytes. An attempt is made to read as many as
len bytes, but a smaller number may be read, possibly
zero. The number of bytes actually read is returned as an integer.
This method blocks until input data is available, end of file is detected, or an exception is thrown.
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.
If len is zero, then no bytes are read and
0 is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at end of
file, the value -1 is returned; otherwise, at least one
byte is read and stored into b.
The first byte read is stored into element b[off], the
next one into b[off+1], and so on. The number of bytes read
is, at most, equal to len. Let k be the number of
bytes actually read; these bytes will be stored in elements
b[off] through b[off+k-1],
leaving elements b[off+k] through
b[off+len-1] unaffected.
In every case, elements b[0] through
b[off] and elements b[off+len] through
b[b.length-1] are unaffected.
If the first byte cannot be read for any reason other than end of
file, then an IOException is thrown. In particular, an
IOException is thrown if the input stream has been closed.
The read(b, off, len) method
for class InputStream simply calls the method
read() repeatedly. If the first such call results in an
IOException, that exception is returned from the call to
the read(b, off, len) method. If
any subsequent call to read() results in a
IOException, the exception is caught and treated as if it
were end of file; the bytes read up to that point are stored into
b and the number of bytes read before the exception
occurred is returned. Subclasses are encouraged to provide a more
efficient implementation of this method.
read in class InputStreamb - the buffer into which the data is read.off - the start offset in array b
at which the data is written.len - the maximum number of bytes to read.
-1 if there is no more data because the end of
the stream has been reached.
IOException - if an I/O error occurs.InputStream.read()
public long skip(long n)
throws IOException
InputStreamn bytes of data from this input
stream. The skip method may, for a variety of reasons, end
up skipping over some smaller number of bytes, possibly 0.
This may result from any of a number of conditions; reaching end of file
before n bytes have been skipped is only one possibility.
The actual number of bytes skipped is returned. If n is
negative, no bytes are skipped.
The skip method of InputStream creates a
byte array and then repeatedly reads into it until n bytes
have been read or the end of the stream has been reached. Subclasses are
encouraged to provide a more efficient implementation of this method.
skip in class InputStreamn - the number of bytes to be skipped.
IOException - if an I/O error occurs.
public int available()
throws IOException
InputStream The available method for class InputStream
always returns 0.
This method should be overridden by subclasses.
available in class InputStreamIOException - if an I/O error occurs.public void mark(int readlimit)
InputStreamreset method repositions this stream at the last marked
position so that subsequent reads re-read the same bytes.
The readlimit arguments tells this input stream to
allow that many bytes to be read before the mark position gets
invalidated.
The general contract of mark is that, if the method
markSupported returns true, the stream somehow
remembers all the bytes read after the call to mark and
stands ready to supply those same bytes again if and whenever the method
reset is called. However, the stream is not required to
remember any data at all if more than readlimit bytes are
read from the stream before reset is called.
The mark method of InputStream does
nothing.
mark in class InputStreamreadlimit - the maximum limit of bytes that can be read before
the mark position becomes invalid.InputStream.reset()
public void reset()
throws IOException
InputStreammark method was last called on this input stream.
The general contract of reset is:
markSupported returns
true, then:
mark has not been called since
the stream was created, or the number of bytes read from the stream
since mark was last called is larger than the argument
to mark at that last call, then an
IOException might be thrown.
IOException is not thrown, then the
stream is reset to a state such that all the bytes read since the
most recent call to mark (or since the start of the
file, if mark has not been called) will be resupplied
to subsequent callers of the read method, followed by
any bytes that otherwise would have been the next input data as of
the time of the call to reset. markSupported returns
false, then:
reset may throw an
IOException.
IOException is not thrown, then the stream
is reset to a fixed state that depends on the particular type of the
input stream and how it was created. The bytes that will be supplied
to subsequent callers of the read method depend on the
particular type of the input stream. The method reset for class InputStream
does nothing and always throws an IOException.
reset in class InputStreamIOException - if this stream has not been marked or if the
mark has been invalidated.InputStream.mark(int),
IOExceptionpublic boolean markSupported()
InputStreammark and
reset methods. The markSupported method of
InputStream returns false.
markSupported in class InputStreamtrue if this true type supports the mark and reset
method; false otherwise.InputStream.mark(int),
InputStream.reset()
public final void readFully(byte[] b)
throws IOException
DataInputb. The number of bytes
read is equal
to the length of b.
This method blocks until one of the following conditions occurs:
b.length
bytes of input data are available, in which
case a normal return is made.
EOFException is thrown.
IOException other than
EOFException is thrown.
If b is null,
a NullPointerException is thrown.
If b.length is zero, then
no bytes are read. Otherwise, the first
byte read is stored into element b[0],
the next one into b[1], and
so on.
If an exception is thrown from
this method, then it may be that some but
not all bytes of b have been
updated with data from the input stream.
readFully in interface DataInputb - the buffer into which the data is read.
EOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public final void readFully(byte[] b,
int off,
int len)
throws IOException
readFully
method of DataInput.
Bytes for this operation are read from the contained input stream.
readFully in interface DataInputb - the buffer into which the data is read.off - the start offset of the data.len - the number of bytes to read.
EOFException - if this input stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public int skipBytes(int n)
throws IOException
n bytes
of data from the input
stream, discarding the skipped bytes. However,
it may skip
over some smaller number of
bytes, possibly zero. This may result from
any of a
number of conditions; reaching
end of file before n bytes
have been skipped is
only one possibility.
This method never throws an EOFException.
The actual
number of bytes skipped is returned.
skipBytes in interface DataInputn - the number of bytes to be skipped.
n.
EOFException - if this stream reaches the end before skipping
all the bytes.
IOException - if an I/O error occurs.
public boolean readBoolean()
throws IOException
true if that byte is nonzero,
false if that byte is zero.
This method is suitable for reading
the byte written by the writeBoolean
method of interface DataOutput.
readBoolean in interface DataInputboolean value read.
EOFException - if this stream reaches the end before reading
all the bytes.
IOException - if an I/O error occurs.
public byte readByte()
throws IOException
-128 through 127,
inclusive.
This method is suitable for
reading the byte written by the writeByte
method of interface DataOutput.
readByte in interface DataInputEOFException - if this stream reaches the end before reading
all the bytes.
IOException - if an I/O error occurs.
public int readUnsignedByte()
throws IOException
int, and returns
the result, which is therefore in the range
0
through 255.
This method is suitable for reading
the byte written by the writeByte
method of interface DataOutput
if the argument to writeByte
was intended to be a value in the range
0 through 255.
readUnsignedByte in interface DataInputEOFException - if this stream reaches the end before reading
all the bytes.
IOException - if an I/O error occurs.
public short readShort()
throws IOException
short value. Let a
be the first byte read and b
be the second byte. The value
returned
is:
(short)((a << 8) * | (b & 0xff))
writeShort method of
interface DataOutput.
readShort in interface DataInputEOFException - if this stream reaches the end before reading
all the bytes.
IOException - if an I/O error occurs.
public final char readChar()
throws IOException
readChar
method of DataInput.
Bytes for this operation are read from the contained input stream.
readChar in interface DataInputEOFException - if this input stream reaches the end before
reading two bytes.
IOException - if an I/O error occurs.
public final float readFloat()
throws IOException
readFloat in interface DataInputEOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public final double readDouble()
throws IOException
readDouble in interface DataInputEOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
public String readUTF()
throws IOException
readUTF
is that it reads a representation of a Unicode
character string encoded in Java modified
UTF-8 format; this string of characters
is then returned as a String.
First, two bytes are read and used to
construct an unsigned 16-bit integer in
exactly the manner of the readUnsignedShort
method . This integer value is called the
UTF length and specifies the number
of additional bytes to be read. These bytes
are then converted to characters by considering
them in groups. The length of each group
is computed from the value of the first
byte of the group. The byte following a
group, if any, is the first byte of the
next group.
If the first byte of a group
matches the bit pattern 0xxxxxxx
(where x means "may be 0
or 1"), then the group consists
of just that byte. The byte is zero-extended
to form a character.
If the first byte
of a group matches the bit pattern 110xxxxx,
then the group consists of that byte a
and a second byte b. If there
is no byte b (because byte
a was the last of the bytes
to be read), or if byte b does
not match the bit pattern 10xxxxxx,
then a UTFDataFormatException
is thrown. Otherwise, the group is converted
to the character:
(char)(((a& 0x1F) << 6) | (b & 0x3F))
1110xxxx,
then the group consists of that byte a
and two more bytes b and c.
If there is no byte c (because
byte a was one of the last
two of the bytes to be read), or either
byte b or byte c
does not match the bit pattern 10xxxxxx,
then a UTFDataFormatException
is thrown. Otherwise, the group is converted
to the character:
(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
1111xxxx or the pattern
10xxxxxx, then a UTFDataFormatException
is thrown.
If end of file is encountered
at any time during this entire process,
then an EOFException is thrown.
After every group has been converted to
a character by this process, the characters
are gathered, in the same order in which
their corresponding groups were read from
the input stream, to form a String,
which is returned.
The writeUTF
method of interface DataOutput
may be used to write data that is suitable
for reading by this method.
readUTF in interface DataInputEOFException - if this stream reaches the end
before reading all the bytes.
IOException - if an I/O error occurs.
UTFDataFormatException - if the bytes do not represent a
valid UTF-8 encoding of a string.
|
" 2013 FRC Java API " |
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