added two way converter

org.springframework.core/src/main/java/org/springframework/core/convert/ConversionExecutionException.java

@@ -22,7 +22,7 @@ import org.springframework.core.style.StylerUtils;
  * 
  * @author Keith Donald
  */
-public class ConversionExecutionException extends ConversionException {
+public class ConversionExecutionException extends ConvertException {
 
 	/**
 	 * The value we tried to convert. Transient because we cannot guarantee that the value is Serializable.

org.springframework.core/src/main/java/org/springframework/core/convert/ConversionService.java

@@ -39,9 +39,7 @@ public interface ConversionService {
 	 * @param targetType context about the target type to convert to
 	 * @return the converted object, an instance of {@link TypeDescriptor#getType()}</code>, or <code>null</code> if a null source
 	 * was provided
-	 * @throws ConverterNotFoundException if no suitable conversion executor could be found to convert the
-	 * source to an instance of targetType
-	 * @throws ConversionException if an exception occurred during the conversion process
+	 * @throws ConvertException if an exception occurred during the conversion process
 	 */
 	public Object convert(Object source, TypeDescriptor targetType);
 

org.springframework.core/src/main/java/org/springframework/core/convert/ConvertException.java

@@ -20,14 +20,14 @@ package org.springframework.core.convert;
  * 
  * @author Keith Donald
  */
-public abstract class ConversionException extends RuntimeException {
+public abstract class ConvertException extends RuntimeException {
 
 	/**
 	 * Creates a new conversion exception.
 	 * @param message the exception message
 	 * @param cause the cause
 	 */
-	public ConversionException(String message, Throwable cause) {
+	public ConvertException(String message, Throwable cause) {
 		super(message, cause);
 	}
 
@@ -35,7 +35,7 @@ public abstract class ConversionException extends RuntimeException {
 	 * Creates a new conversion exception.
 	 * @param message the exception message
 	 */
-	public ConversionException(String message) {
+	public ConvertException(String message) {
 		super(message);
 	}
 }

org.springframework.core/src/main/java/org/springframework/core/convert/ConverterNotFoundException.java

@@ -16,11 +16,11 @@
 package org.springframework.core.convert;
 
 /**
- * Thrown when a conversion executor could not be found in a conversion service.
+ * Thrown when a suitable converter could not be found in a conversion service.
  * 
  * @author Keith Donald
  */
-public class ConverterNotFoundException extends ConversionException {
+public class ConverterNotFoundException extends ConvertException {
 
 	private Class<?> sourceType;
 

org.springframework.core/src/main/java/org/springframework/core/convert/converter/Converter.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.core.convert.converter;
 
-import org.springframework.core.convert.ConversionException;
+import org.springframework.core.convert.ConvertException;
 import org.springframework.core.convert.ConversionService;
 
 /**
@@ -33,19 +33,9 @@ public interface Converter<S, T> {
 	 * @param source the source object to convert, which must be an instance of S
 	 * @return the converted object, which must be an instance of T
 	 * @throws Exception an exception occurred performing the conversion; may be any checked exception, the conversion
-	 * system will handle wrapping the failure in a {@link ConversionException} that provides a consistent type
+	 * system will handle wrapping the failure in a {@link ConvertException} that provides a consistent type
 	 * conversion error context
 	 */
 	public T convert(S source) throws Exception;
 
-	/**
-	 * Convert the target of type T back to source type S.
-	 * @param target the target object to convert, which must be an instance of T
-	 * @return the converted object, which must be an instance of S
-	 * @throws Exception an exception occurred performing the conversion; may be any checked exception, the conversion
-	 * system will handle wrapping the failure in a {@link ConversionException} that provides a consistent type
-	 * conversion error context
-	 */
-	public S convertBack(T target) throws Exception;
-
 }

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToBigDecimal.java

@@ -22,7 +22,7 @@ import java.math.BigDecimal;
  * 
  * @author Keith Donald
  */
-public class StringToBigDecimal implements Converter<String, BigDecimal> {
+public class StringToBigDecimal implements TwoWayConverter<String, BigDecimal> {
 
 	public BigDecimal convert(String source) {
 		return new BigDecimal(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToBigInteger.java

@@ -22,7 +22,7 @@ import java.math.BigInteger;
  * 
  * @author Keith Donald
  */
-public class StringToBigInteger implements Converter<String, BigInteger> {
+public class StringToBigInteger implements TwoWayConverter<String, BigInteger> {
 
 	public BigInteger convert(String source) {
 		return new BigInteger(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToBoolean.java

@@ -23,7 +23,7 @@ import org.springframework.util.Assert;
  * @see #StringToBoolean(String, String)
  * @author Keith Donald
  */
-public class StringToBoolean implements Converter<String, Boolean> {
+public class StringToBoolean implements TwoWayConverter<String, Boolean> {
 
 	private String trueString;
 

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToByte.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToByte implements Converter<String, Byte> {
+public class StringToByte implements TwoWayConverter<String, Byte> {
 
 	public Byte convert(String source) {
 		return Byte.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToCharacter.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToCharacter implements Converter<String, Character> {
+public class StringToCharacter implements TwoWayConverter<String, Character> {
 
 	public Character convert(String source) {
 		if (source.length() != 1) {

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToDouble.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToDouble implements Converter<String, Double> {
+public class StringToDouble implements TwoWayConverter<String, Double> {
 
 	public Double convert(String source) {
 		return Double.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToFloat.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToFloat implements Converter<String, Float> {
+public class StringToFloat implements TwoWayConverter<String, Float> {
 
 	public Float convert(String source) {
 		return Float.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToInteger.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToInteger implements Converter<String, Integer> {
+public class StringToInteger implements TwoWayConverter<String, Integer> {
 
 	public Integer convert(String source) {
 		return Integer.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToLocale.java

@@ -24,7 +24,7 @@ import org.springframework.util.StringUtils;
  * 
  * @author Keith Donald
  */
-public class StringToLocale implements Converter<String, Locale> {
+public class StringToLocale implements TwoWayConverter<String, Locale> {
 
 	public Locale convert(String source) {
 		return StringUtils.parseLocaleString(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToLong.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToLong implements Converter<String, Long> {
+public class StringToLong implements TwoWayConverter<String, Long> {
 
 	public Long convert(String source) {
 		return Long.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToShort.java

@@ -20,7 +20,7 @@ package org.springframework.core.convert.converter;
  * 
  * @author Keith Donald
  */
-public class StringToShort implements Converter<String, Short> {
+public class StringToShort implements TwoWayConverter<String, Short> {
 
 	public Short convert(String source) {
 		return Short.valueOf(source);

org.springframework.core/src/main/java/org/springframework/core/convert/converter/SuperConverter.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.core.convert.converter;
 
-import org.springframework.core.convert.ConversionException;
+import org.springframework.core.convert.ConvertException;
 import org.springframework.core.convert.ConversionService;
 
 /**
@@ -34,7 +34,7 @@ public interface SuperConverter<S, T> {
 	 * @param targetClass the requested target class to convert to (RT), which must be equal to T or extend from T
 	 * @return the converted object, which must be an instance of RT
 	 * @throws Exception an exception occurred performing the conversion; may be any checked exception, the conversion
-	 * system will handle wrapping the failure in a {@link ConversionException} that provides a consistent type
+	 * system will handle wrapping the failure in a {@link ConvertException} that provides a consistent type
 	 * conversion error context
 	 */
 	public <RT extends T> RT convert(S source, Class<RT> targetClass) throws Exception;

org.springframework.core/src/main/java/org/springframework/core/convert/converter/SuperTwoWayConverter.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.core.convert.converter;
 
-import org.springframework.core.convert.ConversionException;
+import org.springframework.core.convert.ConvertException;
 import org.springframework.core.convert.ConversionService;
 
 /**
@@ -34,7 +34,7 @@ public interface SuperTwoWayConverter<S, T> extends SuperConverter<S, T> {
 	 * @param sourceClass the requested source class to convert to, which must be equal to S or extend from S
 	 * @return the converted object, which must be an instance of RS
 	 * @throws Exception an exception occurred performing the conversion; may be any checked exception, the conversion
-	 * system will handle wrapping the failure in a {@link ConversionException} that provides a consistent type
+	 * system will handle wrapping the failure in a {@link ConvertException} that provides a consistent type
 	 * conversion error context
 	 */
 	public <RS extends S> RS convertBack(T target, Class<RS> sourceClass) throws Exception;

org.springframework.core/src/main/java/org/springframework/core/convert/converter/TwoWayConverter.java

@@ -0,0 +1,25 @@
+package org.springframework.core.convert.converter;
+
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.ConvertException;
+
+/**
+ * A converter that can also convert a target object of type T to a source of class S.
+ * <p>
+ * Implementations of this interface are thread-safe and can be shared. Converters are typically registered with and
+ * accessed through a {@link ConversionService}.
+ * </p>
+ * @author Keith Donald
+ */
+public interface TwoWayConverter<S, T> extends Converter<S, T> {
+
+	/**
+	 * Convert the target of type T back to source type S.
+	 * @param target the target object to convert, which must be an instance of T
+	 * @return the converted object, which must be an instance of S
+	 * @throws Exception an exception occurred performing the conversion; may be any checked exception, the conversion
+	 * system will handle wrapping the failure in a {@link ConvertException} that provides a consistent type
+	 * conversion error context
+	 */
+	public S convertBack(T target) throws Exception;
+}

org.springframework.core/src/main/java/org/springframework/core/convert/service/GenericConversionService.java

@@ -33,6 +33,7 @@ import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.ConverterInfo;
 import org.springframework.core.convert.converter.SuperConverter;
 import org.springframework.core.convert.converter.SuperTwoWayConverter;
+import org.springframework.core.convert.converter.TwoWayConverter;
 import org.springframework.util.Assert;
 
 /**
@@ -89,9 +90,11 @@ public class GenericConversionService implements ConversionService {
 		// index forward
 		Map sourceMap = getSourceMap(sourceType);
 		sourceMap.put(targetType, converter);
-		// index reverse
-		sourceMap = getSourceMap(targetType);
-		sourceMap.put(sourceType, new ReverseConverter(converter));
+		if (converter instanceof TwoWayConverter) {
+			// index reverse
+			sourceMap = getSourceMap(targetType);
+			sourceMap.put(sourceType, new ReverseConverter((TwoWayConverter) converter));
+		}
 	}
 
 	/**
@@ -228,7 +231,7 @@ public class GenericConversionService implements ConversionService {
 			for (Type genericInterface : genericInterfaces) {
 				if (genericInterface instanceof ParameterizedType) {
 					ParameterizedType pInterface = (ParameterizedType) genericInterface;
-					if (Converter.class.equals(pInterface.getRawType())
+					if (Converter.class.isAssignableFrom((Class) pInterface.getRawType())
 							|| SuperConverter.class.isAssignableFrom((Class) pInterface.getRawType())) {
 						Class s = getParameterClass(pInterface.getActualTypeArguments()[0], converter.getClass());
 						Class t = getParameterClass(pInterface.getActualTypeArguments()[1], converter.getClass());

org.springframework.core/src/main/java/org/springframework/core/convert/service/ReverseConverter.java

@@ -16,6 +16,7 @@
 package org.springframework.core.convert.service;
 
 import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.TwoWayConverter;
 
 /**
  * A converter that reverses another converter.
@@ -24,17 +25,14 @@ import org.springframework.core.convert.converter.Converter;
 @SuppressWarnings("unchecked")
 class ReverseConverter implements Converter {
 
-	private Converter converter;
+	private TwoWayConverter converter;
 
-	public ReverseConverter(Converter converter) {
+	public ReverseConverter(TwoWayConverter converter) {
 		this.converter = converter;
 	}
 
 	public Object convert(Object source) throws Exception {
 		return converter.convertBack(source);
 	}
-
-	public Object convertBack(Object target) throws Exception {
-		throw new IllegalStateException("Should not be called");
-	}
+	
 }

org.springframework.expression/src/main/java/org/springframework/expression/spel/support/StandardTypeConverter.java

@@ -16,7 +16,7 @@
 
 package org.springframework.expression.spel.support;
 
-import org.springframework.core.convert.ConversionException;
+import org.springframework.core.convert.ConvertException;
 import org.springframework.core.convert.ConverterNotFoundException;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
@@ -55,7 +55,7 @@ public class StandardTypeConverter implements TypeConverter {
 			return conversionService.convert(value, typeDescriptor);
 		} catch (ConverterNotFoundException cenfe) {
 			throw new SpelException(cenfe, SpelMessages.TYPE_CONVERSION_ERROR, value.getClass(), typeDescriptor.asString());
-		} catch (ConversionException ce) {
+		} catch (ConvertException ce) {
 			throw new SpelException(ce, SpelMessages.TYPE_CONVERSION_ERROR, value.getClass(), typeDescriptor.asString());
 		}
 	}