org.springframework.http.codec.json.Jackson2Tokenizer Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* http://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.http.codec.json;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.core.async.ByteArrayFeeder;
import com.fasterxml.jackson.databind.util.TokenBuffer;
import reactor.core.publisher.Flux;
import org.springframework.core.codec.DecodingException;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.util.Assert;
/**
* {@link Function} to transform a JSON stream of arbitrary size, byte array
* chunks into a {@code Flux} where each token buffer is a
* well-formed JSON object.
*
* @author Arjen Poutsma
* @since 5.0
*/
final class Jackson2Tokenizer {
private final JsonParser parser;
private final boolean tokenizeArrayElements;
private TokenBuffer tokenBuffer;
private int objectDepth;
private int arrayDepth;
// TODO: change to ByteBufferFeeder when supported by Jackson
// See https://github.com/FasterXML/jackson-core/issues/478
private final ByteArrayFeeder inputFeeder;
private Jackson2Tokenizer(JsonParser parser, boolean tokenizeArrayElements) {
Assert.notNull(parser, "'parser' must not be null");
this.parser = parser;
this.tokenizeArrayElements = tokenizeArrayElements;
this.tokenBuffer = new TokenBuffer(parser);
this.inputFeeder = (ByteArrayFeeder) this.parser.getNonBlockingInputFeeder();
}
/**
* Tokenize the given {@code Flux} into {@code Flux}.
* @param dataBuffers the source data buffers
* @param jsonFactory the factory to use
* @param tokenizeArrayElements if {@code true} and the "top level" JSON
* object is an array, each element is returned individually, immediately
* after it is received.
* @return the result token buffers
*/
public static Flux tokenize(Flux dataBuffers, JsonFactory jsonFactory,
boolean tokenizeArrayElements) {
try {
JsonParser parser = jsonFactory.createNonBlockingByteArrayParser();
Jackson2Tokenizer tokenizer = new Jackson2Tokenizer(parser, tokenizeArrayElements);
return dataBuffers.flatMap(tokenizer::tokenize, Flux::error, tokenizer::endOfInput);
}
catch (IOException ex) {
return Flux.error(ex);
}
}
private Flux tokenize(DataBuffer dataBuffer) {
byte[] bytes = new byte[dataBuffer.readableByteCount()];
dataBuffer.read(bytes);
DataBufferUtils.release(dataBuffer);
try {
this.inputFeeder.feedInput(bytes, 0, bytes.length);
return parseTokenBufferFlux();
}
catch (JsonProcessingException ex) {
return Flux.error(new DecodingException(
"JSON decoding error: " + ex.getOriginalMessage(), ex));
}
catch (IOException ex) {
return Flux.error(ex);
}
}
private Flux endOfInput() {
this.inputFeeder.endOfInput();
try {
return parseTokenBufferFlux();
}
catch (JsonProcessingException ex) {
return Flux.error(new DecodingException(
"JSON decoding error: " + ex.getOriginalMessage(), ex));
}
catch (IOException ex) {
return Flux.error(ex);
}
}
private Flux parseTokenBufferFlux() throws IOException {
List result = new ArrayList<>();
while (true) {
JsonToken token = this.parser.nextToken();
// SPR-16151: Smile data format uses null to separate documents
if ((token == JsonToken.NOT_AVAILABLE) ||
(token == null && (token = this.parser.nextToken()) == null)) {
break;
}
updateDepth(token);
if (!this.tokenizeArrayElements) {
processTokenNormal(token, result);
}
else {
processTokenArray(token, result);
}
}
return Flux.fromIterable(result);
}
private void updateDepth(JsonToken token) {
switch (token) {
case START_OBJECT:
this.objectDepth++;
break;
case END_OBJECT:
this.objectDepth--;
break;
case START_ARRAY:
this.arrayDepth++;
break;
case END_ARRAY:
this.arrayDepth--;
break;
}
}
private void processTokenNormal(JsonToken token, List result) throws IOException {
this.tokenBuffer.copyCurrentEvent(this.parser);
if ((token.isStructEnd() || token.isScalarValue()) &&
this.objectDepth == 0 && this.arrayDepth == 0) {
result.add(this.tokenBuffer);
this.tokenBuffer = new TokenBuffer(this.parser);
}
}
private void processTokenArray(JsonToken token, List result) throws IOException {
if (!isTopLevelArrayToken(token)) {
this.tokenBuffer.copyCurrentEvent(this.parser);
}
if (this.objectDepth == 0 &&
(this.arrayDepth == 0 || this.arrayDepth == 1) &&
(token == JsonToken.END_OBJECT || token.isScalarValue())) {
result.add(this.tokenBuffer);
this.tokenBuffer = new TokenBuffer(this.parser);
}
}
private boolean isTopLevelArrayToken(JsonToken token) {
return this.objectDepth == 0 && ((token == JsonToken.START_ARRAY && this.arrayDepth == 1) ||
(token == JsonToken.END_ARRAY && this.arrayDepth == 0));
}
}