Package org.springframework.boot.logging

Class CorrelationIdFormatter

java.lang.Object

org.springframework.boot.logging.CorrelationIdFormatter

public final class CorrelationIdFormatter
extends Object

Utility class that can be used to format a correlation identifier for logging based on W3C recommendations.

The formatter can be configured with a comma-separated list of names and the expected length of their resolved value. Each item should be specified in the form "<name>(length)". For example, "traceId(32),spanId(16)" specifies the names "traceId" and "spanId" with expected lengths of 32 and 16 respectively.

Correlation IDs are formatted as dash separated strings surrounded in square brackets. Formatted output is always of a fixed width and with trailing space. Dashes are omitted if none of the named items can be resolved.

The following example would return a formatted result of "[01234567890123456789012345678901-0123456789012345] ":

 CorrelationIdFormatter formatter = CorrelationIdFormatter.of("traceId(32),spanId(16)");
 Map<String, String> mdc = Map.of("traceId", "01234567890123456789012345678901", "spanId", "0123456789012345");
 return formatter.format(mdc::get);
 

If of(String) is called with an empty spec the DEFAULT formatter will be used.

Since:

3.2.0

Author:

Phillip Webb

See Also:

• of(String)
• of(Collection)

Field Summary

Fields

Modifier and Type	Field	Description
static final CorrelationIdFormatter	DEFAULT	Default CorrelationIdFormatter.

Method Summary

Modifier and Type	Method	Description
String	format(UnaryOperator<String> resolver)	Format a correlation from the values in the given resolver.
void	formatTo(UnaryOperator<String> resolver, Appendable appendable)	Format a correlation from the values in the given resolver and append it to the given Appendable.
static CorrelationIdFormatter	of(String spec)	Create a new CorrelationIdFormatter instance from the given specification.
static CorrelationIdFormatter	of(String[] spec)	Create a new CorrelationIdFormatter instance from the given specification.
static CorrelationIdFormatter	of(Collection<String> spec)	Create a new CorrelationIdFormatter instance from the given specification.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT

public static final CorrelationIdFormatter DEFAULT

Default CorrelationIdFormatter.

Method Details

format

public String format(UnaryOperator<String> resolver)

Format a correlation from the values in the given resolver.

Parameters:

resolver - the resolver used to resolve named values

Returns:

a formatted correlation id

formatTo

public void formatTo(UnaryOperator<String> resolver,
 Appendable appendable)

Format a correlation from the values in the given resolver and append it to the given Appendable.

Parameters:

resolver - the resolver used to resolve named values

appendable - the appendable for the formatted correlation id

toString

public String toString()

Overrides:

toString in class Object

of

public static CorrelationIdFormatter of(String spec)

Create a new CorrelationIdFormatter instance from the given specification.

Parameters:

spec - a comma-separated specification

Returns:

a new CorrelationIdFormatter instance

of

public static CorrelationIdFormatter of(String[] spec)

Create a new CorrelationIdFormatter instance from the given specification.

Parameters:

spec - a pre-separated specification

Returns:

a new CorrelationIdFormatter instance

of

public static CorrelationIdFormatter of(Collection<String> spec)

Create a new CorrelationIdFormatter instance from the given specification.

Parameters:

spec - a pre-separated specification

Returns:

a new CorrelationIdFormatter instance