java.lang.Object
- org.springframework.messaging.handler.annotation.support.AbstractNamedValueMethodArgumentResolver

所有已实现的接口:
HandlerMethodArgumentResolver
直接已知子类:
DestinationVariableMethodArgumentResolver, HeaderMethodArgumentResolver
```
public abstract class AbstractNamedValueMethodArgumentResolver
extends Object
implements HandlerMethodArgumentResolver
```
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.
从以下版本开始:
4.0
作者:
Rossen Stoyanchev, Juergen Hoeller

嵌套类概要
嵌套类
修饰符和类型类说明
protected static class AbstractNamedValueMethodArgumentResolver.NamedValueInfo
Represents a named value declaration.

构造器概要

构造器
限定符	构造器	说明
`protected`	`AbstractNamedValueMethodArgumentResolver(ConversionService conversionService, ConfigurableBeanFactory beanFactory)`	Constructor with a `ConversionService` and a `BeanFactory`.

方法概要

所有方法实例方法抽象方法具体方法
修饰符和类型	方法	说明
`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 void`	`handleResolvedValue(Object arg, String name, MethodParameter parameter, Message<?> message)`	Invoked after a value is resolved.
`Object`	`resolveArgument(MethodParameter parameter, Message<?> message)`	Resolves a method parameter into an argument value from a given message.
`protected abstract Object`	`resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)`	Resolves the given parameter type and value name into an argument value.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从接口继承的方法 org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver
supportsParameter

- 构造器详细资料
  - AbstractNamedValueMethodArgumentResolver
```
protected AbstractNamedValueMethodArgumentResolver(ConversionService conversionService,
                                                   @Nullable
                                                   ConfigurableBeanFactory beanFactory)
```
    Constructor with a ConversionService and a BeanFactory.
    参数:
    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
- 方法详细资料
  - resolveArgument
```
public Object resolveArgument(MethodParameter parameter,
                              Message<?> message)
                       throws Exception
```
    从接口复制的说明: HandlerMethodArgumentResolver
    Resolves a method parameter into an argument value from a given message.
    指定者:
    resolveArgument 在接口中 HandlerMethodArgumentResolver
    参数:
    parameter - the method parameter to resolve. This parameter must have previously been passed to HandlerMethodArgumentResolver.supportsParameter(org.springframework.core.MethodParameter) which must have returned true.
    message - the currently processed message
    返回:
    the resolved argument value, or null
    抛出:
    Exception - in case of errors with the preparation of argument values
  - 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).
    参数:
    parameter - the method parameter
    返回:
    the named value information
  - resolveArgumentInternal
```
@Nullable
protected abstract Object resolveArgumentInternal(MethodParameter parameter,
                                                  Message<?> message,
                                                  String name)
                                           throws Exception
```
    Resolves the given parameter type and value name into an argument value.
    参数:
    parameter - the method parameter to resolve to an argument value
    message - the current request
    name - the name of the value being resolved
    返回:
    the resolved argument. May be null
    抛出:
    Exception - in case of errors
  - 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.
    参数:
    name - the name for the value
    parameter - the target method parameter
    message - the message being processed
  - handleResolvedValue
```
protected void handleResolvedValue(@Nullable
                                   Object arg,
                                   String name,
                                   MethodParameter parameter,
                                   Message<?> message)
```
    Invoked after a value is resolved.
    参数:
    arg - the resolved argument value
    name - the argument name
    parameter - the argument parameter type
    message - the message

类 AbstractNamedValueMethodArgumentResolver

嵌套类概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

从接口继承的方法 org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver

构造器详细资料

AbstractNamedValueMethodArgumentResolver

方法详细资料

resolveArgument

createNamedValueInfo

resolveArgumentInternal

handleMissingValue

handleResolvedValue