All decoder fallbacks must implement a decoder fallback buffer, represented by a type derived from the DecoderFallbackBuffer class, that can pass a string to the conversion operation.

• 所有解码器回退必须实现解码器回退缓冲区(该缓冲区通过从DecoderFallbackBuffer类派生的类型表示),这样,就可以将字符串传递给转换操作。