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, RequestAttributeMethodArgumentResolver, RequestHeaderMethodArgumentResolver, RequestParamMethodArgumentResolver, SessionAttributeMethodArgumentResolver

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, Juergen Hoeller

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) Create a new AbstractNamedValueMethodArgumentResolver instance.

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 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	handleMissingValue(String name, MethodParameter parameter, NativeWebRequest request) Invoked when a named value is required, but resolveName(String, MethodParameter, NativeWebRequest) returned null and there is no default value.
protected void	handleMissingValueAfterConversion(String name, MethodParameter parameter, NativeWebRequest request) Invoked when a named value is present but becomes null after conversion.
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) Resolve 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(@Nullable
                                                ConfigurableBeanFactory beanFactory)

Create a new AbstractNamedValueMethodArgumentResolver instance.

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

@Nullable
public final Object resolveArgument(MethodParameter parameter,
                                              @Nullable
                                              ModelAndViewContainer mavContainer,
                                              NativeWebRequest webRequest,
                                              @Nullable
                                              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 if not resolvable

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

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

Resolve 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 (pre-nested in case of a Optional declaration)

request - the current request

Returns:

the resolved argument (may be null)

Throws:

Exception - in case of errors

handleMissingValue

protected void handleMissingValue(String name,
                                  MethodParameter parameter,
                                  NativeWebRequest request)
                           throws Exception

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

request - the current request

Throws:

Exception

Since:

4.3

handleMissingValue

protected 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

handleMissingValueAfterConversion

protected void handleMissingValueAfterConversion(String name,
                                                 MethodParameter parameter,
                                                 NativeWebRequest request)
                                          throws Exception

Invoked when a named value is present but becomes null after conversion.

Parameters:

name - the name for the value

parameter - the method parameter

request - the current request

Throws:

Exception

Since:

5.3.6

handleResolvedValue

protected void handleResolvedValue(@Nullable
                                   Object arg,
                                   String name,
                                   MethodParameter parameter,
                                   @Nullable
                                   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 (may be null)

webRequest - the current request