/*
* Copyright 2002-2010 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.expression.common;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypeConverter;
import org.springframework.expression.TypedValue;
import org.springframework.util.ClassUtils;
/**
* Common utility functions that may be used by any Expression Language provider.
*
* @author Andy Clement
* @author Juergen Hoeller
* @since 3.0
*/
public abstract class ExpressionUtils {
/**
* Determines if there is a type converter available in the specified context and attempts to use it to convert the
* supplied value to the specified type. Throws an exception if conversion is not possible.
* @param context the evaluation context that may define a type converter
* @param value the value to convert (may be null)
* @param targetType the type to attempt conversion to
* @return the converted value
* @throws EvaluationException if there is a problem during conversion or conversion of the value to the specified
* type is not supported
*/
public static <T> T convert(EvaluationContext context, Object value, Class<T> targetType) throws EvaluationException {
// TODO remove this function over time and use the one it delegates to
return convertTypedValue(context,new TypedValue(value,TypeDescriptor.forObject(value)),targetType);
}
/**
* Determines if there is a type converter available in the specified context and attempts to use it to convert the
* supplied value to the specified type. Throws an exception if conversion is not possible.
* @param context the evaluation context that may define a type converter
* @param typedValue the value to convert and a type descriptor describing it
* @param targetType the type to attempt conversion to
* @return the converted value
* @throws EvaluationException if there is a problem during conversion or conversion of the value to the specified
* type is not supported
*/
@SuppressWarnings("unchecked")
public static <T> T convertTypedValue(EvaluationContext context, TypedValue typedValue, Class<T> targetType) {
Object value = typedValue.getValue();
if (targetType == null || ClassUtils.isAssignableValue(targetType, value)) {
return (T) value;
}
if (context != null) {
return (T) context.getTypeConverter().convertValue(value, typedValue.getTypeDescriptor(), TypeDescriptor.valueOf(targetType));
}
throw new EvaluationException("Cannot convert value '" + value + "' to type '" + targetType.getName() + "'");
}
/**
* Attempt to convert a typed value to an int using the supplied type converter.
*/
public static int toInt(TypeConverter typeConverter, TypedValue typedValue) {
return (Integer) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(),
TypeDescriptor.valueOf(Integer.class));
}
/**
* Attempt to convert a typed value to a boolean using the supplied type converter.
*/
public static boolean toBoolean(TypeConverter typeConverter, TypedValue typedValue) {
return (Boolean) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(),
TypeDescriptor.valueOf(Boolean.class));
}
/**
* Attempt to convert a typed value to a double using the supplied type converter.
*/
public static double toDouble(TypeConverter typeConverter, TypedValue typedValue) {
return (Double) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(),
TypeDescriptor.valueOf(Double.class));
}
/**
* Attempt to convert a typed value to a long using the supplied type converter.
*/
public static long toLong(TypeConverter typeConverter, TypedValue typedValue) {
return (Long) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(), TypeDescriptor
.valueOf(Long.class));
}
/**
* Attempt to convert a typed value to a char using the supplied type converter.
*/
public static char toChar(TypeConverter typeConverter, TypedValue typedValue) {
return (Character) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(),
TypeDescriptor.valueOf(Character.class));
}
/**
* Attempt to convert a typed value to a short using the supplied type converter.
*/
public static short toShort(TypeConverter typeConverter, TypedValue typedValue) {
return (Short) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(), TypeDescriptor
.valueOf(Short.class));
}
/**
* Attempt to convert a typed value to a float using the supplied type converter.
*/
public static float toFloat(TypeConverter typeConverter, TypedValue typedValue) {
return (Float) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(), TypeDescriptor
.valueOf(Float.class));
}
/**
* Attempt to convert a typed value to a byte using the supplied type converter.
*/
public static byte toByte(TypeConverter typeConverter, TypedValue typedValue) {
return (Byte) typeConverter.convertValue(typedValue.getValue(), typedValue.getTypeDescriptor(), TypeDescriptor
.valueOf(Byte.class));
}
}
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