Class AbstractNamedValueMethodArgumentResolver

java.lang.Object

org.springframework.messaging.handler.annotation.reactive.AbstractNamedValueMethodArgumentResolver

All Implemented Interfaces:

HandlerMethodArgumentResolver, SyncHandlerMethodArgumentResolver

Direct Known Subclasses:

DestinationVariableMethodArgumentResolver, HeaderMethodArgumentResolver

public abstract class AbstractNamedValueMethodArgumentResolver
extends Object
implements SyncHandlerMethodArgumentResolver

Abstract base class to resolve method arguments from a named value, for example, message headers or destination variables. Named values could have one or more of a name, a required flag, and a default value.

Subclasses only need to define specific steps such as how to obtain named value details from a method parameter, how to resolve to argument values, or how to handle missing values.

A default value string can contain ${...} placeholders and Spring Expression Language #{...} expressions which will be resolved if a ConfigurableBeanFactory is supplied to the class constructor.

A ConversionService is used to convert a resolved String argument value to the expected target method parameter type.

Since:

5.2

Author:

Rossen Stoyanchev

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractNamedValueMethodArgumentResolver.NamedValueInfo	Represents a named value declaration.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractNamedValueMethodArgumentResolver(ConversionService conversionService, @Nullable ConfigurableBeanFactory beanFactory)	Constructor with a ConversionService and a BeanFactory.

Method Summary

Modifier and Type	Method	Description
protected abstract AbstractNamedValueMethodArgumentResolver.NamedValueInfo	createNamedValueInfo(MethodParameter parameter)	Create the AbstractNamedValueMethodArgumentResolver.NamedValueInfo object for the given method parameter.
protected abstract void	handleMissingValue(String name, MethodParameter parameter, Message<?> message)	Invoked when a value is required, but resolveArgumentInternal(MethodParameter, Message, String) returned null and there is no default value.
protected abstract @Nullable Object	resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)	Resolves the given parameter type and value name into an argument value.
@Nullable Object	resolveArgumentValue(MethodParameter parameter, Message<?> message)	Resolve the value for the method parameter synchronously.

Methods inherited from class Object

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

Methods inherited from interface HandlerMethodArgumentResolver

supportsParameter

Methods inherited from interface SyncHandlerMethodArgumentResolver

resolveArgument

Constructor Details

AbstractNamedValueMethodArgumentResolver

protected AbstractNamedValueMethodArgumentResolver(ConversionService conversionService,
 @Nullable ConfigurableBeanFactory beanFactory)

Constructor with a ConversionService and a BeanFactory.

Parameters:

conversionService - conversion service for converting String values to the target method parameter type

beanFactory - a bean factory for resolving ${...} placeholders and #{...} SpEL expressions in default values

Method Details

resolveArgumentValue

public @Nullable Object resolveArgumentValue(MethodParameter parameter,
 Message<?> message)

Description copied from interface: SyncHandlerMethodArgumentResolver

Resolve the value for the method parameter synchronously.

Specified by:

resolveArgumentValue in interface SyncHandlerMethodArgumentResolver

Parameters:

parameter - the method parameter

message - the currently processed message

Returns:

the resolved value, if any

createNamedValueInfo

protected abstract AbstractNamedValueMethodArgumentResolver.NamedValueInfo createNamedValueInfo(MethodParameter parameter)

Create the AbstractNamedValueMethodArgumentResolver.NamedValueInfo object for the given method parameter. Implementations typically retrieve the method annotation by means of MethodParameter.getParameterAnnotation(Class).

Parameters:

parameter - the method parameter

Returns:

the named value information

resolveArgumentInternal

protected abstract @Nullable Object resolveArgumentInternal(MethodParameter parameter,
 Message<?> message,
 String name)

Resolves the given parameter type and value name into an argument value.

Parameters:

parameter - the method parameter to resolve to an argument value

message - the current request

name - the name of the value being resolved

Returns:

the resolved argument. May be null

handleMissingValue

protected abstract void handleMissingValue(String name,
 MethodParameter parameter,
 Message<?> message)

Invoked when a value is required, but resolveArgumentInternal(MethodParameter, Message, String) returned null and there is no default value. Subclasses can throw an appropriate exception for this case.

Parameters:

name - the name for the value

parameter - the target method parameter

message - the message being processed