org.springframework.kafka.support

Class DefaultKafkaHeaderMapper

java.lang.Object

org.springframework.kafka.support.AbstractKafkaHeaderMapper

org.springframework.kafka.support.DefaultKafkaHeaderMapper

All Implemented Interfaces:

KafkaHeaderMapper

public class DefaultKafkaHeaderMapper
extends AbstractKafkaHeaderMapper

Default header mapper for Apache Kafka. Most headers in KafkaHeaders are not mapped on outbound messages. The exceptions are correlation and reply headers for request/reply messaging. Header types are added to a special header JSON_TYPES.

Since:

1.3

Author:

Gary Russell, Artem Bilan

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DefaultKafkaHeaderMapper.NonTrustedHeaderType Represents a header that could not be decoded due to an untrusted type.

Nested classes/interfaces inherited from class org.springframework.kafka.support.AbstractKafkaHeaderMapper

AbstractKafkaHeaderMapper.HeaderMatcher, AbstractKafkaHeaderMapper.NeverMatchHeaderMatcher, AbstractKafkaHeaderMapper.SimplePatternBasedHeaderMatcher

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	JSON_TYPES Header name for java types of other headers.

Fields inherited from class org.springframework.kafka.support.AbstractKafkaHeaderMapper

logger

Constructor Summary

Constructors

Constructor and Description
DefaultKafkaHeaderMapper() Construct an instance with the default object mapper and default header patterns for outbound headers; all inbound headers are mapped.
DefaultKafkaHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper) Construct an instance with the provided object mapper and default header patterns for outbound headers; all inbound headers are mapped.
DefaultKafkaHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper, java.lang.String... patterns) Construct an instance with the provided object mapper and the provided header patterns for outbound headers; all inbound headers are mapped.
DefaultKafkaHeaderMapper(java.lang.String... patterns) Construct an instance with a default object mapper and the provided header patterns for outbound headers; all inbound headers are mapped.

Method Summary

Modifier and Type	Method and Description
void	addToStringClasses(java.lang.String... classNames) Add class names that the outbound mapper should perform toString() operations on before mapping.
void	addTrustedPackages(java.lang.String... packagesToTrust) Add packages to the trusted packages list (default java.util, java.lang) used when constructing objects from JSON.
void	fromHeaders(org.springframework.messaging.MessageHeaders headers, org.apache.kafka.common.header.Headers target) Map from the given MessageHeaders to the specified target message.
protected com.fasterxml.jackson.databind.ObjectMapper	getObjectMapper() Return the object mapper.
protected java.util.Set<java.lang.String>	getToStringClasses() Provide direct access to the toString() classes by subclasses.
protected java.util.Set<java.lang.String>	getTrustedPackages() Provide direct access to the trusted packages set for subclasses.
protected boolean	isEncodeStrings()
void	setEncodeStrings(boolean encodeStrings) Set to true to encode String-valued headers as JSON ("..."), by default just the raw String value is converted to a byte array using the configured charset.
void	toHeaders(org.apache.kafka.common.header.Headers source, java.util.Map<java.lang.String,java.lang.Object> headers) Map from the given target message to abstracted MessageHeaders.
protected boolean	trusted(java.lang.String requestedType)

Methods inherited from class org.springframework.kafka.support.AbstractKafkaHeaderMapper

addMatchers, getCharset, headerValueToAddIn, headerValueToAddOut, matches, matches, setCharset, setMapAllStringsOut, setRawMappedHeaders

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

JSON_TYPES

public static final java.lang.String JSON_TYPES

Header name for java types of other headers.

See Also:

Constant Field Values

Constructor Detail

DefaultKafkaHeaderMapper

public DefaultKafkaHeaderMapper()

Construct an instance with the default object mapper and default header patterns for outbound headers; all inbound headers are mapped. The default pattern list is "!id", "!timestamp" and "*". In addition, most of the headers in KafkaHeaders are never mapped as headers since they represent data in consumer/producer records.

See Also:

DefaultKafkaHeaderMapper(ObjectMapper)

DefaultKafkaHeaderMapper

public DefaultKafkaHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper)

Construct an instance with the provided object mapper and default header patterns for outbound headers; all inbound headers are mapped. The patterns are applied in order, stopping on the first match (positive or negative). Patterns are negated by preceding them with "!". The default pattern list is "!id", "!timestamp" and "*". In addition, most of the headers in KafkaHeaders are never mapped as headers since they represent data in consumer/producer records.

Parameters:

objectMapper - the object mapper.

See Also:

PatternMatchUtils.simpleMatch(String, String)

DefaultKafkaHeaderMapper

public DefaultKafkaHeaderMapper(java.lang.String... patterns)

Construct an instance with a default object mapper and the provided header patterns for outbound headers; all inbound headers are mapped. The patterns are applied in order, stopping on the first match (positive or negative). Patterns are negated by preceding them with "!". The patterns will replace the default patterns; you generally should not map the "id" and "timestamp" headers. Note: most of the headers in KafkaHeaders are ever mapped as headers since they represent data in consumer/producer records.

Parameters:

patterns - the patterns.

See Also:

PatternMatchUtils.simpleMatch(String, String)

DefaultKafkaHeaderMapper

public DefaultKafkaHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper,
                                java.lang.String... patterns)

Construct an instance with the provided object mapper and the provided header patterns for outbound headers; all inbound headers are mapped. The patterns are applied in order, stopping on the first match (positive or negative). Patterns are negated by preceding them with "!". The patterns will replace the default patterns; you generally should not map the "id" and "timestamp" headers. Note: most of the headers in KafkaHeaders are never mapped as headers since they represent data in consumer/producer records.

Parameters:

objectMapper - the object mapper.

patterns - the patterns.

See Also:

PatternMatchUtils.simpleMatch(String, String)

Method Detail

getObjectMapper

protected com.fasterxml.jackson.databind.ObjectMapper getObjectMapper()

Return the object mapper.

Returns:

the mapper.

getTrustedPackages

protected java.util.Set<java.lang.String> getTrustedPackages()

Provide direct access to the trusted packages set for subclasses.

Returns:

the trusted packages.

Since:

2.2

getToStringClasses

protected java.util.Set<java.lang.String> getToStringClasses()

Provide direct access to the toString() classes by subclasses.

Returns:

the toString() classes.

Since:

2.2

isEncodeStrings

protected boolean isEncodeStrings()

setEncodeStrings

public void setEncodeStrings(boolean encodeStrings)

Set to true to encode String-valued headers as JSON ("..."), by default just the raw String value is converted to a byte array using the configured charset. Set to true if a consumer of the outbound record is using Spring for Apache Kafka version less than 2.3

Parameters:

encodeStrings - true to encode (default false).

Since:

2.3

addTrustedPackages

public void addTrustedPackages(java.lang.String... packagesToTrust)

Add packages to the trusted packages list (default java.util, java.lang) used when constructing objects from JSON. If any of the supplied packages is "*", all packages are trusted. If a class for a non-trusted package is encountered, the header is returned to the application with value of type DefaultKafkaHeaderMapper.NonTrustedHeaderType.

Parameters:

packagesToTrust - the packages to trust.

addToStringClasses

public void addToStringClasses(java.lang.String... classNames)

Add class names that the outbound mapper should perform toString() operations on before mapping.

Parameters:

classNames - the class names.

Since:

2.2

fromHeaders

public void fromHeaders(org.springframework.messaging.MessageHeaders headers,
                        org.apache.kafka.common.header.Headers target)

Description copied from interface: KafkaHeaderMapper

Map from the given MessageHeaders to the specified target message.

Parameters:

headers - the abstracted MessageHeaders.

target - the native target message.

toHeaders

public void toHeaders(org.apache.kafka.common.header.Headers source,
                      java.util.Map<java.lang.String,java.lang.Object> headers)

Description copied from interface: KafkaHeaderMapper

Map from the given target message to abstracted MessageHeaders.

Parameters:

source - the native target message.

headers - the target headers.

trusted

protected boolean trusted(java.lang.String requestedType)