All Known Implementing Classes:

GzipFilter, HatanakaCompressFilter, NsgfV00Filter, TruncatingFilter, UnixCompressFilter
```
public interface DataFilter
```
Interface for filtering data (typically uncompressing it) in data providers before passing it to data loaders.

Since:

9.2

Author:

Luc Maisonobe

See Also:

DataProvider, DataLoader

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  DataSource filter(DataSource original)
  Filter the data source.

- Method Detail
  - filter
```
DataSource filter(DataSource original)
           throws IOException
```
    Filter the data source.
    Filtering is often based on suffix. For example a gzip compressed file will have an original name of the form base.ext.gz when the corresponding uncompressed file will have a filtered name base.ext.
    
    A filter must never open the DataSource by itself, regardless of the fact it will return the original instance or a filtered instance. The rationale is that it is the upper layer that will decide to open (or not) the returned value and that a DataSource can be opened only once; this is the core principle of lazy-opening provided by DataSource.
    
    Beware that as the data providers manager will attempt to pile all filters in a stack as long as their implementation of this method returns a value different from the original parameter. This implies that the filter, must perform some checks to see if it must be applied or not. If for example there is a need for a deciphering filter to be applied once to all data, then the filter should for example check for a suffix in the name and create a new filtered DataSource instance only if the suffix is present, removing the suffix from the filtered instance. Failing to do so and simply creating a filtered instance with one deciphering layer without changing the name would result in an infinite stack of deciphering filters being built, until a stack overflow or memory exhaustion exception occurs.
    
    Parameters:
    
    original - original data source
    
    Returns:
    
    filtered data source, or original if this filter does not apply to this data source
    
    Throws:
    
    IOException - if filtered stream cannot be created

Interface DataFilter

Method Summary

Method Detail

filter