Package org.springframework.messaging.handler.annotation.reactive

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, 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(org.springframework.core.MethodParameter, org.springframework.messaging.Message<?>, java.lang.String) returned null and there is no default value.
protected abstract Object	resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)	Resolves the given parameter type and value name into an argument value.
Object	resolveArgumentValue(MethodParameter parameter, Message<?> message)	Resolve the value for the method parameter synchronously.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.messaging.handler.invocation.reactive.HandlerMethodArgumentResolver

supportsParameter

Methods inherited from interface org.springframework.messaging.handler.invocation.reactive.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

@Nullable
public 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

@Nullable
protected abstract 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(org.springframework.core.MethodParameter, org.springframework.messaging.Message<?>, java.lang.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