Interface WebArgumentResolver

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface WebArgumentResolver

SPI for resolving custom arguments for a specific handler method parameter. Typically implemented to detect special parameter types, resolving well-known argument values for them.

A typical implementation could look like as follows:

public class MySpecialArgumentResolver implements WebArgumentResolver {

  public Object resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest) {
    if (methodParameter.getParameterType().equals(MySpecialArg.class)) {
      return new MySpecialArg("myValue");
    }
    return UNRESOLVED;
  }
}

Since:

2.5.2

Author:

Juergen Hoeller

See Also:

• RequestMappingHandlerAdapter.setCustomArgumentResolvers(List)

Field Summary

Fields

Modifier and Type	Field	Description
static final Object	UNRESOLVED	Marker to be returned when the resolver does not know how to handle the given method parameter.

Method Summary

Modifier and Type	Method	Description
@Nullable Object	resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest)	Resolve an argument for the given handler method parameter within the given web request.

Field Details

UNRESOLVED

static final Object UNRESOLVED

Marker to be returned when the resolver does not know how to handle the given method parameter.

Method Details

resolveArgument

@Nullable Object resolveArgument(MethodParameter methodParameter,
 NativeWebRequest webRequest)
                          throws Exception

Resolve an argument for the given handler method parameter within the given web request.

Parameters:

methodParameter - the handler method parameter to resolve

webRequest - the current web request, allowing access to the native request as well

Returns:

the argument value, or UNRESOLVED if not resolvable

Throws:

Exception - in case of resolution failure