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(org.springframework.core.convert.TypeDescriptor sourceType, org.springframework.core.convert.TypeDescriptor targetType) Return true if the type converter can convert the specified type to the desired target type.
Object	convertValue(Object value, org.springframework.core.convert.TypeDescriptor sourceType, org.springframework.core.convert.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
                   org.springframework.core.convert.TypeDescriptor sourceType,
                   org.springframework.core.convert.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
                              org.springframework.core.convert.TypeDescriptor sourceType,
                              org.springframework.core.convert.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