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, e.g. 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

All Methods Instance Methods Abstract Methods Concrete Methods
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 Detail
  - 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 Detail
  - resolveArgumentValue
```
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. Sub-classes 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

Class AbstractNamedValueMethodArgumentResolver

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

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

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

Constructor Detail

AbstractNamedValueMethodArgumentResolver

Method Detail

resolveArgumentValue

createNamedValueInfo

resolveArgumentInternal

handleMissingValue