org.springframework.context.expression.BeanExpressionContextAccessor.java Source code

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Here is the source code for org.springframework.context.expression.BeanExpressionContextAccessor.java

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/*
 * Copyright 2002-2017 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.context.expression;

import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypedValue;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * EL property accessor that knows how to traverse the beans and contextual objects
 * of a Spring {@link org.springframework.beans.factory.config.BeanExpressionContext}.
 *
 * @author Juergen Hoeller
 * @author Andy Clement
 * @since 3.0
 */
public class BeanExpressionContextAccessor implements PropertyAccessor {

    @Override
    public boolean canRead(EvaluationContext context, @Nullable Object target, String name) throws AccessException {
        return (target instanceof BeanExpressionContext && ((BeanExpressionContext) target).containsObject(name));
    }

    @Override
    public TypedValue read(EvaluationContext context, @Nullable Object target, String name) throws AccessException {
        Assert.state(target instanceof BeanExpressionContext, "Target must be of type BeanExpressionContext");
        return new TypedValue(((BeanExpressionContext) target).getObject(name));
    }

    @Override
    public boolean canWrite(EvaluationContext context, @Nullable Object target, String name)
            throws AccessException {
        return false;
    }

    @Override
    public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue)
            throws AccessException {

        throw new AccessException("Beans in a BeanFactory are read-only");
    }

    @Override
    public Class<?>[] getSpecificTargetClasses() {
        return new Class<?>[] { BeanExpressionContext.class };
    }

}