com.ibm.tivoli.maximo.antivirus.impl.icap.net

Class LineInputStream

java.lang.Object

java.io.InputStream

com.ibm.tivoli.maximo.antivirus.impl.icap.net.LineInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

Direct Known Subclasses:

SocketInputStream

public class LineInputStream
extends java.io.InputStream

This LineInputStream class sacrifices performance to make sure it doesn't read beyond the end of line. That means that unless otherwise requested, it reads one character at a time. This will mean that it stops reading at \r and only reads further to see if there is a subsequent \n when you ask it to do the next read. This can be useful if the caller wants to read a number of lines and then continue reading directly from the source stream. It's also useful if the source is a socket stream because sometimes it blocks if you do a block read for more data than is available.

Field Summary

Fields

Modifier and Type	Field and Description
static byte[]	baEmpty
static byte[]	baEmptyDone

Constructor Summary

Constructors

Constructor and Description
LineInputStream(java.io.InputStream isSource)

Method Summary

Methods

Modifier and Type	Method and Description
int	_read()
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) Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
byte[]	readLineBytes(int maxsize) This method returns the next line of characters up to the maxsize parameter without returning the line terminating characters.
byte[]	readLineTerminatorBytes() Get the characters that terminated that last line.
void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long len) Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

baEmptyDone

public static final byte[] baEmptyDone

baEmpty

public static final byte[] baEmpty

Constructor Detail

LineInputStream

public LineInputStream(java.io.InputStream isSource)

Method Detail

_read

public int _read()
          throws java.io.IOException

Throws:

java.io.IOException

readLineBytes

public byte[] readLineBytes(int maxsize)
                     throws java.io.IOException

This method returns the next line of characters up to the maxsize parameter without returning the line terminating characters. The first line terminator character will be read from the underlying stream. If the line is terminated by a pair of characters, both of those can be obtained by the getLineTerminator() method. With the exception of getLineTerminator(), all subsequent read calls will skip past the line terminator char(s).

Throws:

java.io.IOException

readLineTerminatorBytes

public byte[] readLineTerminatorBytes()
                               throws java.io.IOException

Get the characters that terminated that last line. If this last call to this stream was not a call to readLineBytes(), then this method returns an empty string.

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Reads the next byte of data from the input stream. The value byte is returned as an int 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.

Specified by:

read in class java.io.InputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

java.io.IOException - if an I/O error occurs.

read

public int read(byte[] b,
       int off,
       int len)
         throws java.io.IOException

Reads up to len 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.

Overrides:

read in class java.io.InputStream

Parameters:

b - 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.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

InputStream.read()

read

public int read(byte[] b)
         throws java.io.IOException

Reads some number of bytes from the input stream and stores them into the buffer array b. 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 the length of b 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[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] 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) method for class InputStream has the same effect as:

 read(b, 0, b.length) 

Overrides:

read in class java.io.InputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

InputStream.read(byte[], int, int)

mark

public void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the reset 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.

Overrides:

mark in class java.io.InputStream

Parameters:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

InputStream.reset()

skip

public long skip(long len)
          throws java.io.IOException

Skips over and discards n 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.

Overrides:

skip in class java.io.InputStream

Parameters:

len - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

java.io.IOException - if an I/O error occurs.

available

public int available()
              throws java.io.IOException

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. The next caller might be the same thread or or another thread.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Overrides:

available in class java.io.InputStream

Returns:

the number of bytes that can be read from this input stream without blocking.

Throws:

java.io.IOException - if an I/O error occurs.

close

public void close()
           throws java.io.IOException

Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException - if an I/O error occurs.

reset

public void reset()
           throws java.io.IOException

Repositions this stream to the position at the time the mark method was last called on this input stream.

The general contract of reset is:

• If the method markSupported returns true, then:
  • If the method 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.
  • If such an 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.
• If the method markSupported returns false, then:
  • The call to reset may throw an IOException.
  • If an 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.

Overrides:

reset in class java.io.InputStream

Throws:

java.io.IOException - if this stream has not been marked or if the mark has been invalidated.

See Also:

InputStream.mark(int), IOException

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. The markSupported method of InputStream returns false.

Overrides:

markSupported in class java.io.InputStream

Returns:

true if this true type supports the mark and reset method; false otherwise.

See Also:

InputStream.mark(int), InputStream.reset()