org.springframework.web.method.annotation

Class AbstractNamedValueMethodArgumentResolver

java.lang.Object

org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver

All Implemented Interfaces:

HandlerMethodArgumentResolver

Direct Known Subclasses:

AbstractCookieValueMethodArgumentResolver, ExpressionValueMethodArgumentResolver, MatrixVariableMethodArgumentResolver, PathVariableMethodArgumentResolver, RequestHeaderMethodArgumentResolver, RequestParamMethodArgumentResolver

public abstract class AbstractNamedValueMethodArgumentResolver
extends Object
implements HandlerMethodArgumentResolver

Abstract base class for resolving method arguments from a named value. Request parameters, request headers, and path variables are examples of named values. Each may have a name, a required flag, and a default value.

Subclasses define how to do the following:

• Obtain named value information for a method parameter
• Resolve names into argument values
• Handle missing argument values when argument values are required
• Optionally handle a resolved value

A default value string can contain ${...} placeholders and Spring Expression Language #{...} expressions. For this to work a ConfigurableBeanFactory must be supplied to the class constructor.

A WebDataBinder is created to apply type conversion to the resolved argument value if it doesn't match the method parameter type.

Since:

3.1

Author:

Arjen Poutsma, Rossen Stoyanchev

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	AbstractNamedValueMethodArgumentResolver.NamedValueInfo Represents the information about a named value, including name, whether it's required and a default value.

Constructor Summary

Constructors

Constructor and Description
AbstractNamedValueMethodArgumentResolver()
AbstractNamedValueMethodArgumentResolver(ConfigurableBeanFactory beanFactory)

Method Summary

Modifier and Type	Method and 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) Invoked when a named value is required, but resolveName(String, MethodParameter, NativeWebRequest) returned null and there is no default value.
protected void	handleResolvedValue(Object arg, String name, MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) Invoked after a value is resolved.
Object	resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) Resolves a method parameter into an argument value from a given request.
protected abstract Object	resolveName(String name, MethodParameter parameter, NativeWebRequest request) Resolves the given parameter type and value name into an argument value.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.web.method.support.HandlerMethodArgumentResolver

supportsParameter

Constructor Detail

AbstractNamedValueMethodArgumentResolver

public AbstractNamedValueMethodArgumentResolver()

AbstractNamedValueMethodArgumentResolver

public AbstractNamedValueMethodArgumentResolver(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

resolveArgument

public final Object resolveArgument(MethodParameter parameter,
                                    ModelAndViewContainer mavContainer,
                                    NativeWebRequest webRequest,
                                    WebDataBinderFactory binderFactory)
                             throws Exception

Description copied from interface: HandlerMethodArgumentResolver

Resolves a method parameter into an argument value from a given request. A ModelAndViewContainer provides access to the model for the request. A WebDataBinderFactory provides a way to create a WebDataBinder instance when needed for data binding and type conversion purposes.

Specified by:

resolveArgument in interface HandlerMethodArgumentResolver

Parameters:

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.

mavContainer - the ModelAndViewContainer for the current request

webRequest - the current request

binderFactory - a factory for creating WebDataBinder instances

Returns:

the resolved argument value, or null

Throws:

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).

Parameters:

parameter - the method parameter

Returns:

the named value information

resolveName

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

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

Parameters:

name - the name of the value being resolved

parameter - the method parameter to resolve to an argument value

request - the current request

Returns:

the resolved argument. May be null

Throws:

Exception - in case of errors

handleMissingValue

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

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

Parameters:

name - the name for the value

parameter - the method parameter

Throws:

ServletException

handleResolvedValue

protected void handleResolvedValue(Object arg,
                                   String name,
                                   MethodParameter parameter,
                                   ModelAndViewContainer mavContainer,
                                   NativeWebRequest webRequest)

Invoked after a value is resolved.

Parameters:

arg - the resolved argument value

name - the argument name

parameter - the argument parameter type

mavContainer - the ModelAndViewContainer, which may be null

webRequest - the current request