org.springframework.kafka.support.serializer.ParseStringDeserializer Maven / Gradle / Ivy
/*
* Copyright 2016-2020 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.kafka.support.serializer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import java.util.function.BiFunction;
import java.util.function.Function;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.serialization.Deserializer;
import org.springframework.util.Assert;
/**
* Generic {@link org.apache.kafka.common.serialization.Deserializer Deserializer} for deserialization of entity from
* its {@link String} representation received from Kafka (a.k.a parsing).
*
* @param class of the entity, representing messages
*
* @author Alexei Klenin
* @author Gary Russell
* @since 2.5
*/
public class ParseStringDeserializer implements Deserializer {
/**
* Property for the key parser method.
*/
public static final String KEY_PARSER = "spring.message.key.parser";
/**
* Property for the key parser method.
*/
public static final String VALUE_PARSER = "spring.message.value.parser";
private static final BiFunction NO_PARSER = (str, headers) -> {
throw new IllegalStateException("A parser must be provided either via a constructor or consumer properties");
};
@SuppressWarnings("unchecked")
private BiFunction parser = (BiFunction) NO_PARSER;
private Charset charset = StandardCharsets.UTF_8;
/**
* Construct an instance with no parser function; a static method name must be
* provided in the consumer config {@link #KEY_PARSER} or {@link #VALUE_PARSER}
* properties.
*/
public ParseStringDeserializer() {
}
/**
* Construct an instance with the supplied parser function.
* @param parser the function.
*/
public ParseStringDeserializer(Function parser) {
this.parser = (message, ignoredHeaders) -> parser.apply(message);
}
/**
* Construct an instance with the supplied parser function.
* @param parser the function.
*/
public ParseStringDeserializer(BiFunction parser) {
this.parser = parser;
}
@Override
public void configure(Map configs, boolean isKey) {
if (NO_PARSER.equals(this.parser)) {
String parserMethod = (String) configs.get(isKey ? KEY_PARSER : VALUE_PARSER);
Assert.state(parserMethod != null,
"A parser must be provided either via a constructor or consumer properties");
this.parser = SerializationUtils.propertyToMethodInvokingFunction(parserMethod, String.class,
getClass().getClassLoader());
}
}
@Override
public T deserialize(String topic, byte[] data) {
return deserialize(topic, null, data);
}
@Override
public T deserialize(String topic, Headers headers, byte[] data) {
return this.parser.apply(new String(data, this.charset), headers);
}
/**
* Set a charset to use when converting byte[] to {@link String}. Default UTF-8.
* @param charset the charset.
*/
public void setCharset(Charset charset) {
Assert.notNull(charset, "'charset' cannot be null");
this.charset = charset;
}
/**
* Get the configured charset.
* @return the charset.
*/
public Charset getCharset() {
return this.charset;
}
/**
* Get the configured parser function.
* @return the function.
*/
public BiFunction getParser() {
return this.parser;
}
}