spring-kafka JsonSerializer 源码
spring-kafka JsonSerializer 代码
文件路径:/spring-kafka/src/main/java/org/springframework/kafka/support/serializer/JsonSerializer.java
/*
* Copyright 2016-2021 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.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.header.Headers;
import org.apache.kafka.common.serialization.Serializer;
import org.springframework.kafka.support.JacksonUtils;
import org.springframework.kafka.support.mapping.AbstractJavaTypeMapper;
import org.springframework.kafka.support.mapping.DefaultJackson2JavaTypeMapper;
import org.springframework.kafka.support.mapping.Jackson2JavaTypeMapper;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectWriter;
/**
* Generic {@link org.apache.kafka.common.serialization.Serializer Serializer} for sending
* Java objects to Kafka as JSON.
* <p>
* IMPORTANT: Configuration must be done completely with property setters or via
* {@link #configure(Map, boolean)}, not a mixture. If any setters have been called,
* {@link #configure(Map, boolean)} will be a no-op.
*
* @param <T> class of the entity, representing messages
*
* @author Igor Stepanov
* @author Artem Bilan
* @author Gary Russell
* @author Elliot Kennedy
*/
public class JsonSerializer<T> implements Serializer<T> {
/**
* Kafka config property for disabling adding type headers.
*/
public static final String ADD_TYPE_INFO_HEADERS = "spring.json.add.type.headers";
/**
* Kafka config property to add type mappings to the type mapper:
* 'foo:com.Foo,bar:com.Bar'.
*/
public static final String TYPE_MAPPINGS = "spring.json.type.mapping";
protected final ObjectMapper objectMapper; // NOSONAR
protected boolean addTypeInfo = true; // NOSONAR
private ObjectWriter writer;
protected Jackson2JavaTypeMapper typeMapper = new DefaultJackson2JavaTypeMapper(); // NOSONAR
private boolean typeMapperExplicitlySet = false;
private boolean setterCalled;
private boolean configured;
public JsonSerializer() {
this((JavaType) null, JacksonUtils.enhancedObjectMapper());
}
public JsonSerializer(TypeReference<? super T> targetType) {
this(targetType, JacksonUtils.enhancedObjectMapper());
}
public JsonSerializer(ObjectMapper objectMapper) {
this((JavaType) null, objectMapper);
}
public JsonSerializer(TypeReference<? super T> targetType, ObjectMapper objectMapper) {
this(targetType == null ? null : objectMapper.constructType(targetType.getType()), objectMapper);
}
public JsonSerializer(JavaType targetType, ObjectMapper objectMapper) {
Assert.notNull(objectMapper, "'objectMapper' must not be null.");
this.objectMapper = objectMapper;
this.writer = objectMapper.writerFor(targetType);
}
public boolean isAddTypeInfo() {
return this.addTypeInfo;
}
/**
* Set to false to disable adding type info headers.
* @param addTypeInfo true to add headers.
* @since 2.1
*/
public void setAddTypeInfo(boolean addTypeInfo) {
this.addTypeInfo = addTypeInfo;
this.setterCalled = true;
}
public Jackson2JavaTypeMapper getTypeMapper() {
return this.typeMapper;
}
/**
* Set a customized type mapper.
* @param typeMapper the type mapper.
* @since 2.1
*/
public void setTypeMapper(Jackson2JavaTypeMapper typeMapper) {
Assert.notNull(typeMapper, "'typeMapper' cannot be null");
this.typeMapper = typeMapper;
this.typeMapperExplicitlySet = true;
this.setterCalled = true;
}
/**
* Configure the default Jackson2JavaTypeMapper to use key type headers.
* @param isKey Use key type headers if true
* @since 2.1.3
*/
public void setUseTypeMapperForKey(boolean isKey) {
if (!this.typeMapperExplicitlySet && getTypeMapper() instanceof AbstractJavaTypeMapper) {
((AbstractJavaTypeMapper) getTypeMapper())
.setUseForKey(isKey);
}
this.setterCalled = true;
}
@Override
public synchronized void configure(Map<String, ?> configs, boolean isKey) {
if (this.configured) {
return;
}
Assert.state(!this.setterCalled
|| (!configs.containsKey(ADD_TYPE_INFO_HEADERS) && !configs.containsKey(TYPE_MAPPINGS)),
"JsonSerializer must be configured with property setters, or via configuration properties; not both");
setUseTypeMapperForKey(isKey);
if (configs.containsKey(ADD_TYPE_INFO_HEADERS)) {
Object config = configs.get(ADD_TYPE_INFO_HEADERS);
if (config instanceof Boolean) {
this.addTypeInfo = (Boolean) config;
}
else if (config instanceof String) {
this.addTypeInfo = Boolean.valueOf((String) config);
}
else {
throw new IllegalStateException(ADD_TYPE_INFO_HEADERS + " must be Boolean or String");
}
}
if (configs.containsKey(TYPE_MAPPINGS) && !this.typeMapperExplicitlySet
&& this.typeMapper instanceof AbstractJavaTypeMapper) {
((AbstractJavaTypeMapper) this.typeMapper)
.setIdClassMapping(createMappings((String) configs.get(TYPE_MAPPINGS)));
}
this.configured = true;
}
protected static Map<String, Class<?>> createMappings(String mappings) {
Map<String, Class<?>> mappingsMap = new HashMap<>();
String[] array = StringUtils.commaDelimitedListToStringArray(mappings);
for (String entry : array) {
String[] split = entry.split(":");
Assert.isTrue(split.length == 2, "Each comma-delimited mapping entry must have exactly one ':'");
try {
mappingsMap.put(split[0].trim(),
ClassUtils.forName(split[1].trim(), ClassUtils.getDefaultClassLoader()));
}
catch (ClassNotFoundException | LinkageError e) {
throw new IllegalArgumentException("Failed to load: " + split[1] + " for " + split[0], e);
}
}
return mappingsMap;
}
@Override
@Nullable
public byte[] serialize(String topic, Headers headers, @Nullable T data) {
if (data == null) {
return null;
}
if (this.addTypeInfo && headers != null) {
this.typeMapper.fromJavaType(this.objectMapper.constructType(data.getClass()), headers);
}
return serialize(topic, data);
}
@Override
@Nullable
public byte[] serialize(String topic, @Nullable T data) {
if (data == null) {
return null;
}
try {
return this.writer.writeValueAsBytes(data);
}
catch (IOException ex) {
throw new SerializationException("Can't serialize data [" + data + "] for topic [" + topic + "]", ex);
}
}
@Override
public void close() {
// No-op
}
/**
* Copies this serializer with same configuration, except new target type reference is used.
* @param newTargetType type reference forced for serialization, not null
* @param <X> new serialization source type
* @return new instance of serializer with type changes
* @since 2.6
*/
public <X> JsonSerializer<X> copyWithType(Class<? super X> newTargetType) {
return copyWithType(this.objectMapper.constructType(newTargetType));
}
/**
* Copies this serializer with same configuration, except new target type reference is used.
* @param newTargetType type reference forced for serialization, not null
* @param <X> new serialization source type
* @return new instance of serializer with type changes
* @since 2.6
*/
public <X> JsonSerializer<X> copyWithType(TypeReference<? super X> newTargetType) {
return copyWithType(this.objectMapper.constructType(newTargetType.getType()));
}
/**
* Copies this serializer with same configuration, except new target java type is used.
* @param newTargetType java type forced for serialization, not null
* @param <X> new serialization source type
* @return new instance of serializer with type changes
* @since 2.6
*/
public <X> JsonSerializer<X> copyWithType(JavaType newTargetType) {
JsonSerializer<X> result = new JsonSerializer<>(newTargetType, this.objectMapper);
result.addTypeInfo = this.addTypeInfo;
result.typeMapper = this.typeMapper;
result.typeMapperExplicitlySet = this.typeMapperExplicitlySet;
return result;
}
// Fluent API
/**
* Designate this serializer for serializing keys (default is values); only applies if
* the default type mapper is used.
* @return the serializer.
* @since 2.3
* @see #setUseTypeMapperForKey(boolean)
*/
public JsonSerializer<T> forKeys() {
setUseTypeMapperForKey(true);
return this;
}
/**
* Do not include type info headers.
* @return the serializer.
* @since 2.3
* @see #setAddTypeInfo(boolean)
*/
public JsonSerializer<T> noTypeInfo() {
setAddTypeInfo(false);
return this;
}
/**
* Use the supplied {@link Jackson2JavaTypeMapper}.
* @param mapper the mapper.
* @return the serializer.
* @since 2.3
* @see #setTypeMapper(Jackson2JavaTypeMapper)
*/
public JsonSerializer<T> typeMapper(Jackson2JavaTypeMapper mapper) {
setTypeMapper(mapper);
return this;
}
}
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