EncodingDecoder class abstract interface

A unified abstraction for text encoding and decoding operations, providing a consistent interface for converting between raw bytes and human-readable strings across multiple character encodings.

The EncodingDecoder interface defines a contract for encoding and decoding text data in different formats such as UTF-8, ISO-8859-1, ASCII, and others. It enables seamless integration of custom or platform-specific codecs within JetLeaf’s I/O and HTTP subsystems, including file uploads, request parsing, and response serialization.

Responsibilities

• Decode byte arrays into strings using a specified character encoding.
• Encode strings into byte arrays for transmission or storage.
• Report supported encodings and provide introspection capabilities.
• Validate encoding availability to ensure cross-platform compatibility.

Design Notes

• Implementations should use lossless encoding whenever possible to preserve data integrity.
• The default encoding is 'utf-8', which is recommended for most use cases.
• Encoders and decoders must handle both text and binary-safe transformations.
• When unsupported encodings are requested, implementations should either throw descriptive exceptions or fall back to UTF-8 gracefully.
• Commonly used within JetLeaf’s HTTP request/response, multipart, and file I/O handling layers.

Example

final decoder = DefaultEncodingDecoder();

// Decode UTF-8 bytes
final text = decoder.decode(Uint8List.fromList([72, 101, 108, 108, 111]));
print(text); // "Hello"

// Encode a string
final bytes = decoder.encode("JetLeaf");
print(bytes); // [74, 101, 116, 76, 101, 97, 102]

// Check for supported encodings
if (decoder.supportsEncoding("iso-8859-1")) {
  print("ISO-8859-1 is supported!");
}

Typical Implementations

• DefaultEncodingDecoder — Built-in UTF-8 and ISO-8859-1 support.
• CustomEncodingDecoder — Pluggable codec provider for extended charset support.
• PlatformEncodingDecoder — Uses native system libraries for charset operations.

See Also

• dart:convert.Encoding — Standard Dart encoding utilities.
• InputStreamSource — For working with encoded stream data.
• HttpBody — For decoding text-based HTTP payloads.