## org.springframework.web.method.annotation
Class ExpressionValueMethodArgumentResolver

    java.lang.Object
      org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver
          org.springframework.web.method.annotation.ExpressionValueMethodArgumentResolver

All Implemented Interfaces:
  HandlerMethodArgumentResolver

    public class ExpressionValueMethodArgumentResolver

extends AbstractNamedValueMethodArgumentResolver

Resolves method arguments annotated with `@Value`.

An `@Value` does not have a name but gets resolved from the default value string, which may contain ${...} placeholder or Spring Expression Language #{...} expressions.

A `WebDataBinder` may be invoked to apply type conversion to resolved argument value.

Since:
  3.1
Author:
  Rossen Stoyanchev

Nested Class Summary

Nested classes/interfaces inherited from class org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver
`AbstractNamedValueMethodArgumentResolver.NamedValueInfo`

Constructor Summary
`ExpressionValueMethodArgumentResolver(ConfigurableBeanFactory beanFactory)`

Method Summary
`protected AbstractNamedValueMethodArgumentResolver.NamedValueInfo` `createNamedValueInfo(MethodParameter parameter)` Create the `AbstractNamedValueMethodArgumentResolver.NamedValueInfo` object for the given method parameter.
`protected void` `handleMissingValue(String name, MethodParameter parameter)` Invoked when a named value is required, but `AbstractNamedValueMethodArgumentResolver.resolveName(String, MethodParameter, NativeWebRequest)` returned `null` and there is no default value.
`protected Object` `resolveName(String name, MethodParameter parameter, NativeWebRequest webRequest)` Resolves the given parameter type and value name into an argument value.
`boolean` `supportsParameter(MethodParameter parameter)` Whether the given method parameter is supported by this resolver.

Methods inherited from class org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver
`handleResolvedValue, resolveArgument`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### ExpressionValueMethodArgumentResolver

    public ExpressionValueMethodArgumentResolver(ConfigurableBeanFactory beanFactory)

Parameters:
  `beanFactory` - a bean factory to use for resolving ${...} placeholder and #{...} SpEL expressions in default values; or `null` if default values are not expected to contain expressions

Method Detail

### supportsParameter

    public boolean supportsParameter(MethodParameter parameter)

  Description copied from interface: `HandlerMethodArgumentResolver`
  Whether the given method parameter is supported by this resolver.

  Parameters:
    `parameter` - the method parameter to check
  Returns:
    `true` if this resolver supports the supplied parameter; `false` otherwise

### createNamedValueInfo

    protected AbstractNamedValueMethodArgumentResolver.NamedValueInfo createNamedValueInfo(MethodParameter parameter)

  Description copied from class: `AbstractNamedValueMethodArgumentResolver`
  Create the `AbstractNamedValueMethodArgumentResolver.NamedValueInfo` object for the given method parameter. Implementations typically retrieve the method annotation by means of `MethodParameter.getParameterAnnotation(Class)`.

  Specified by:
    `createNamedValueInfo` in class `AbstractNamedValueMethodArgumentResolver`
  Parameters:
    `parameter` - the method parameter
  Returns:
    the named value information

### resolveName

    protected Object resolveName(String name,
                                 MethodParameter parameter,
                                 NativeWebRequest webRequest)
                          throws Exception

  Description copied from class: `AbstractNamedValueMethodArgumentResolver`
  Resolves the given parameter type and value name into an argument value.

  Specified by:
    `resolveName` in class `AbstractNamedValueMethodArgumentResolver`
  Parameters:
    `name` - the name of the value being resolved
    `parameter` - the method parameter to resolve to an argument value
    `webRequest` - the current request
  Returns:
    the resolved argument. May be `null`
  Throws:
    `Exception` - in case of errors

### handleMissingValue

    protected void handleMissingValue(String name,
                                      MethodParameter parameter)
                               throws ServletException

  Description copied from class: `AbstractNamedValueMethodArgumentResolver`
  Invoked when a named value is required, but `AbstractNamedValueMethodArgumentResolver.resolveName(String, MethodParameter, NativeWebRequest)` returned `null` and there is no default value. Subclasses typically throw an exception in this case.

  Specified by:
    `handleMissingValue` in class `AbstractNamedValueMethodArgumentResolver`
  Parameters:
    `name` - the name for the value
    `parameter` - the method parameter
  Throws:
    `ServletException`