org.springframework.cloud.stream.binder.kafka

Class BinderHeaderMapper

java.lang.Object

org.springframework.kafka.support.AbstractKafkaHeaderMapper

org.springframework.cloud.stream.binder.kafka.BinderHeaderMapper

All Implemented Interfaces:

org.springframework.kafka.support.KafkaHeaderMapper

public class BinderHeaderMapper
extends org.springframework.kafka.support.AbstractKafkaHeaderMapper

Custom header mapper for Apache Kafka. This is identical to the DefaultKafkaHeaderMapper from spring Kafka. This is provided for addressing some interoperability issues between Spring Cloud Stream 3.0.x and 2.x apps, where mime types passed as regular MimeType in the header are not de-serialized properly. It also suppresses certain internal headers that should never be propagated on output. Most headers in KafkaHeaders are not mapped onto outbound messages. The exceptions are correlation and reply headers for request/reply messaging. Header types are added to a special header JSON_TYPES.

Since:

3.0.0

Author:

Gary Russell, Artem Bilan, Soby Chacko

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BinderHeaderMapper.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

org.springframework.kafka.support.AbstractKafkaHeaderMapper.HeaderMatcher, org.springframework.kafka.support.AbstractKafkaHeaderMapper.NeverMatchHeaderMatcher, org.springframework.kafka.support.AbstractKafkaHeaderMapper.SimplePatternBasedHeaderMatcher

Field Summary

Fields

Modifier and Type	Field and Description
static 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
BinderHeaderMapper() Construct an instance with the default object mapper and default header patterns for outbound headers; all inbound headers are mapped.
BinderHeaderMapper(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.
BinderHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper, String... patterns) Construct an instance with the provided object mapper and the provided header patterns for outbound headers; all inbound headers are mapped.
BinderHeaderMapper(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
static String[]	addNeverHeaderPatterns(List<String> patterns) Add patterns for headers that should never be mapped.
void	addToStringClasses(String... classNames) Add class names that the outbound mapper should perform toString() operations on before mapping.
void	addTrustedPackages(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)
protected com.fasterxml.jackson.databind.ObjectMapper	getObjectMapper() Return the object mapper.
protected Set<String>	getToStringClasses() Provide direct access to the toString() classes by subclasses.
protected Set<String>	getTrustedPackages() Provide direct access to the trusted packages set for subclasses.
protected boolean	isEncodeStrings()
static void	removeNeverHeaders(org.apache.kafka.common.header.Headers headers) Remove never headers.
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, Map<String,Object> headers)
protected boolean	trusted(String requestedType)

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

addMatchers, addRawMappedHeader, getCharset, headerValueToAddIn, headerValueToAddOut, matches, matches, matchesForInbound, 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 String JSON_TYPES

Header name for java types of other headers.

See Also:

Constant Field Values

Constructor Detail

BinderHeaderMapper

public BinderHeaderMapper()

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:

BinderHeaderMapper(ObjectMapper)

BinderHeaderMapper

public BinderHeaderMapper(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)

BinderHeaderMapper

public BinderHeaderMapper(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)

BinderHeaderMapper

public BinderHeaderMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper,
                          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 Set<String> getTrustedPackages()

Provide direct access to the trusted packages set for subclasses.

Returns:

the trusted packages.

Since:

2.2

getToStringClasses

protected Set<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(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 BinderHeaderMapper.NonTrustedHeaderType.

Parameters:

packagesToTrust - the packages to trust.

addToStringClasses

public void addToStringClasses(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)

toHeaders

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

trusted

protected boolean trusted(String requestedType)

addNeverHeaderPatterns

public static String[] addNeverHeaderPatterns(List<String> patterns)

Add patterns for headers that should never be mapped.

Parameters:

patterns - the patterns.

Returns:

the modified patterns.

Since:

3.0.2

removeNeverHeaders

public static void removeNeverHeaders(org.apache.kafka.common.header.Headers headers)

Remove never headers.

Parameters:

headers - the headers from which to remove the never headers.

Since:

3.0.2