org.springframework.expression

Interface TypeConverter

All Known Implementing Classes:

StandardTypeConverter

public interface TypeConverter

A type converter can convert values between different types encountered during expression evaluation. This is an SPI for the expression parser; see ConversionService for the primary user API to Spring's conversion facilities.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller

Method Summary

Modifier and Type	Method and Description
boolean	canConvert(TypeDescriptor sourceType, TypeDescriptor targetType) Return true if the type converter can convert the specified type to the desired target type.
Object	convertValue(Object value, TypeDescriptor sourceType, TypeDescriptor targetType) Convert (or coerce) a value from one type to another, for example from a boolean to a String.

Method Detail

canConvert

boolean canConvert(@Nullable
                   TypeDescriptor sourceType,
                   TypeDescriptor targetType)

Return true if the type converter can convert the specified type to the desired target type.

Parameters:

sourceType - a type descriptor that describes the source type

targetType - a type descriptor that describes the requested result type

Returns:

true if that conversion can be performed

convertValue

@Nullable
Object convertValue(@Nullable
                              Object value,
                              @Nullable
                              TypeDescriptor sourceType,
                              TypeDescriptor targetType)

Convert (or coerce) a value from one type to another, for example from a boolean to a String.

The TypeDescriptor parameters enable support for typed collections: A caller may prefer a List<Integer>, for example, rather than simply any List.

Parameters:

value - the value to be converted

sourceType - a type descriptor that supplies extra information about the source object

targetType - a type descriptor that supplies extra information about the requested result type

Returns:

the converted value

Throws:

EvaluationException - if conversion failed or is not possible to begin with