Interface for a channel end supporting read filtering operations. A channel end that implements this
interface can have instances of the Filter
interface installed to apply transformations
on data as it is read from the channel.
Multiple filters can be installed and referenced by a zero-based index to specify a specific ordering.
If multiple filters are installed, they are applied in order of increasing index. For example:
FilteredChannelInput in = ...; Filter f1 = ...; Filter f2 = ...; in.addReadFilter (f1, 0); in.addReadFilter (f2, 1);
The in.read()
method will return f2.filter (f1.filter (obj))
where
obj
is the data value that would have been delivered in the absence of filters.
Type | Name and description |
---|---|
void |
addReadFilter(Filter filter) Installs a read filter defining a transformation to be applied by the read method of the
channel end. |
void |
addReadFilter(Filter filter, int index) Installs a read filter defining a transformation to be applied by the read method of the
channel end at a specific index. |
Filter |
getReadFilter(int index) Returns the read filter installed at the given index. |
int |
getReadFilterCount() Returns the number of read filters currently installed. |
void |
removeReadFilter(Filter filter) Removes the first read filter (lowest index) matching the filter given as a parameter. |
void |
removeReadFilter(int index) Removes the read filter installed at the given index. |
Installs a read filter defining a transformation to be applied by the read
method of the
channel end. The filter will be appended to the end of the current list, making it the last to
be applied.
filter
- the filter to be installed; may not be null. Installs a read filter defining a transformation to be applied by the read
method of the
channel end at a specific index. If there is already a filter at that index position the existing
filters are shifted to make room. If the index is greater than the number of filters already
installed the filter is placed at the end.
filter
- the filter to be installed; may not be null.index
- the zero based index; may not be negative.Returns the read filter installed at the given index.
index
- zero-based index of the filter to return.Returns the number of read filters currently installed.
Removes the first read filter (lowest index) matching the filter given as a parameter. The filter
removed, r
, will satisfy the condition r.equals (filter)
. The remaining
filters are shifted to close the gap in the index allocation.
filter
- the filter to be removed; may not be null.Removes the read filter installed at the given index. The remaining filters are shifted to close the gap in the index allocation.
index
- zero-based index of the filter to be removed.