|
qflib 0.98.0 | ||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.io.InputStream | +--de.qfs.lib.util.InputStreamAdapter | +--de.qfs.lib.util.CountingInputStream
This class adapts an InputStream to count the bytes read from it. It
notifies its registered CountListeners
whenever some
bytes are successfully read from the stream.
The intention of this class is to provide the necessary data for a progress
bar while parsing some input file, where the size of the file is known in
advance. For this reason there is no similar CountingReader, since the
number of (possibly multibyte) characters in a file cannot be determined in
advance. In effect a CountingReader can be created with the help of
new InputStreamReader(new CountingInputStream(...))
.
Field Summary | |
protected long |
count
The current byte count for the stream. |
protected java.util.Vector |
listeners
The registered CountListeners. |
protected long |
mark
The byte count for the mark position. |
Fields inherited from class de.qfs.lib.util.InputStreamAdapter |
stream |
Constructor Summary | |
CountingInputStream(java.io.InputStream stream)
Create a new CountingInputStream. |
Method Summary | |
void |
addCountListener(CountListener listener)
Register a new CountListener. |
protected void |
fireCountChanged(long count)
Notify all registered listeners of a change in the read count. |
void |
mark(int readlimit)
Marks the current position in this input stream. |
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. |
void |
removeCountListener(CountListener listener)
Unregister a CountListener. |
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. |
Methods inherited from class de.qfs.lib.util.InputStreamAdapter |
available, close, markSupported |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
protected long count
protected long mark
protected java.util.Vector listeners
Constructor Detail |
public CountingInputStream(java.io.InputStream stream)
stream
- The InputStream used for delegation.Method Detail |
public void mark(int readlimit)
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. Marks the current position in this input stream.
mark
in class InputStreamAdapter
readlimit
- The maximum limit of bytes that can be read
before the mark position becomes invalid.public int read() throws java.io.IOException
read
in class InputStreamAdapter
java.io.IOException
- If an I/O error occurs.public int read(byte[] b) throws java.io.IOException
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.
read
in class InputStreamAdapter
b
- The buffer into which the data is read.java.io.IOException
- If an I/O error occurs.public int read(byte[] b, int off, int len) throws java.io.IOException
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 InputStreamAdapter
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.java.io.IOException
- If an I/O error occurs.public void reset() throws java.io.IOException
reset
in class InputStreamAdapter
java.io.IOException
- If an I/O error occurs.public long skip(long n) throws java.io.IOException
skip
in class InputStreamAdapter
n
- The number of bytes to be skipped.java.io.IOException
- If an I/O error occurs.public void addCountListener(CountListener listener)
listener
- The listener to register.public void removeCountListener(CountListener listener)
listener
- The listener to unregister.protected void fireCountChanged(long count)
|
qflib 0.98.0 | ||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |