org.springframework.expression.PropertyAccessor Maven / Gradle / Ivy
Show all versions of spring-expression Show documentation
/*
* Copyright 2002-2024 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
*
* https://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;
import org.jspecify.annotations.Nullable;
/**
* A property accessor is able to read from (and possibly write to) an object's
* properties.
*
* This interface places no restrictions on what constitutes a property.
* Implementors are therefore free to access properties directly via fields,
* through getters, or in any other way they deem appropriate.
*
*
A property accessor can specify an array of
* {@linkplain #getSpecificTargetClasses() target classes} for which it should be
* called. See {@link TargetedAccessor} for details.
*
* @author Andy Clement
* @since 3.0
* @see TargetedAccessor
* @see IndexAccessor
*/
public interface PropertyAccessor extends TargetedAccessor {
/**
* Called to determine if this property accessor is able to read a specified
* property on a specified target object.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the property is being accessed
* @param name the name of the property being accessed
* @return true if this property accessor is able to read the property
* @throws AccessException if there is any problem determining whether the
* property can be read
*/
boolean canRead(EvaluationContext context, @Nullable Object target, String name) throws AccessException;
/**
* Called to read a property from a specified target object.
*
Should only succeed if {@link #canRead} also returns {@code true}.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the property is being accessed
* @param name the name of the property being accessed
* @return a TypedValue object wrapping the property value read and a type
* descriptor for it
* @throws AccessException if there is any problem reading the property value
*/
TypedValue read(EvaluationContext context, @Nullable Object target, String name) throws AccessException;
/**
* Called to determine if this property accessor is able to write to a specified
* property on a specified target object.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the property is being accessed
* @param name the name of the property being accessed
* @return true if this property accessor is able to write to the property
* @throws AccessException if there is any problem determining whether the
* property can be written to
*/
boolean canWrite(EvaluationContext context, @Nullable Object target, String name) throws AccessException;
/**
* Called to write to a property on a specified target object.
*
Should only succeed if {@link #canWrite} also returns {@code true}.
* @param context the evaluation context in which the access is being attempted
* @param target the target object upon which the property is being accessed
* @param name the name of the property being accessed
* @param newValue the new value for the property
* @throws AccessException if there is any problem writing to the property value
*/
void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue)
throws AccessException;
}