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Encoders

The org.apache.juneau.encoders package defines an API for handling encoding-based matching of Accept-Encoding/Content-Encoding HTTP headers.

It consists of the following classes:

EncoderSetEncoderIdentityEncoderGzipEncoder

EncoderSet​

The EncoderSet class represents the set of org.apache.juneau.encoders keyed by codings. It maintains a set of encoders and the codings that they can handle.

The getEncoderMatch(String) and EncoderSet.getEncoder(String) methods are then used to find appropriate encoders for specific Accept-Encoding and Content-Encoding header values.

Match ordering​

Encoders are tried in the order they appear in the set. The EncoderSet.Builder.add(Class...) / EncoderSet.Builder.add(Encoder...) methods prepend the values to the list to allow them the opportunity to override encoders already in the list.

For example, calling builder.add(E1.class,E2.class).add(E3.class, E4.class) will result in the order E3, E4, E1, E2.

Example
// Create an encoder group with support for gzip compression.
EncoderSet encoders = EncoderSet
    .create()
    .add(GzipEncoder.class)
    .build();

// Should return "gzip"
String matchedCoding = encoders.findMatch("compress;q=1.0, gzip;q=0.8, identity;q=0.5, *;q=0");

// Get the encoder
Encoder encoder = encoders.getEncoder(matchedCoding);

Encoder API​

The Encoder interface is used for enabling decompression on requests and compression on responses, such as support for GZIP compression. It is used to wrap input and output streams within compression/decompression streams.

EncodergetCodings()getInputStream(InputStream)getOutputStream(OutputStream)
note

Encoders are registered with RestServlets through the @Rest(encoders) annotation.