/*
* Copyright 2002-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.core.codec;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
Strategy for decoding a DataBuffer
input stream into an output stream of elements of type <T>
. Author: Sebastien Deleuze, Rossen Stoyanchev Type parameters: - <T> – the type of elements in the output stream
Since: 5.0
/**
* Strategy for decoding a {@link DataBuffer} input stream into an output stream
* of elements of type {@code <T>}.
*
* @author Sebastien Deleuze
* @author Rossen Stoyanchev
* @since 5.0
* @param <T> the type of elements in the output stream
*/
public interface Decoder<T> {
Whether the decoder supports the given target element type and the MIME
type of the source stream.
Params: - elementType – the target element type for the output stream
- mimeType – the mime type associated with the stream to decode (can be
null
if not specified)
Returns: true
if supported, false
otherwise
/**
* Whether the decoder supports the given target element type and the MIME
* type of the source stream.
* @param elementType the target element type for the output stream
* @param mimeType the mime type associated with the stream to decode
* (can be {@code null} if not specified)
* @return {@code true} if supported, {@code false} otherwise
*/
boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType);
Decode a DataBuffer
input stream into a Flux of T
. Params: - inputStream – the
DataBuffer
input stream to decode - elementType – the expected type of elements in the output stream; this type must have been previously passed to the
canDecode
method and it must have returned true
. - mimeType – the MIME type associated with the input stream (optional)
- hints – additional information about how to do encode
Returns: the output stream with decoded elements
/**
* Decode a {@link DataBuffer} input stream into a Flux of {@code T}.
* @param inputStream the {@code DataBuffer} input stream to decode
* @param elementType the expected type of elements in the output stream;
* this type must have been previously passed to the {@link #canDecode}
* method and it must have returned {@code true}.
* @param mimeType the MIME type associated with the input stream (optional)
* @param hints additional information about how to do encode
* @return the output stream with decoded elements
*/
Flux<T> decode(Publisher<DataBuffer> inputStream, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map<String, Object> hints);
Decode a DataBuffer
input stream into a Mono of T
. Params: - inputStream – the
DataBuffer
input stream to decode - elementType – the expected type of elements in the output stream; this type must have been previously passed to the
canDecode
method and it must have returned true
. - mimeType – the MIME type associated with the input stream (optional)
- hints – additional information about how to do encode
Returns: the output stream with the decoded element
/**
* Decode a {@link DataBuffer} input stream into a Mono of {@code T}.
* @param inputStream the {@code DataBuffer} input stream to decode
* @param elementType the expected type of elements in the output stream;
* this type must have been previously passed to the {@link #canDecode}
* method and it must have returned {@code true}.
* @param mimeType the MIME type associated with the input stream (optional)
* @param hints additional information about how to do encode
* @return the output stream with the decoded element
*/
Mono<T> decodeToMono(Publisher<DataBuffer> inputStream, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map<String, Object> hints);
Decode a data buffer to an Object of type T. This is useful for scenarios,
that distinct messages (or events) are decoded and handled individually,
in fully aggregated form.
Params: - buffer – the
DataBuffer
to decode - targetType – the expected output type
- mimeType – the MIME type associated with the data
- hints – additional information about how to do encode
Returns: the decoded value, possibly null
Since: 5.2
/**
* Decode a data buffer to an Object of type T. This is useful for scenarios,
* that distinct messages (or events) are decoded and handled individually,
* in fully aggregated form.
* @param buffer the {@code DataBuffer} to decode
* @param targetType the expected output type
* @param mimeType the MIME type associated with the data
* @param hints additional information about how to do encode
* @return the decoded value, possibly {@code null}
* @since 5.2
*/
@Nullable
default T decode(DataBuffer buffer, ResolvableType targetType,
@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) throws DecodingException {
CompletableFuture<T> future = decodeToMono(Mono.just(buffer), targetType, mimeType, hints).toFuture();
Assert.state(future.isDone(), "DataBuffer decoding should have completed.");
Throwable failure;
try {
return future.get();
}
catch (ExecutionException ex) {
failure = ex.getCause();
}
catch (InterruptedException ex) {
failure = ex;
}
throw (failure instanceof CodecException ? (CodecException) failure :
new DecodingException("Failed to decode: " + failure.getMessage(), failure));
}
Return the list of MIME types this decoder supports.
/**
* Return the list of MIME types this decoder supports.
*/
List<MimeType> getDecodableMimeTypes();
}