org.springframework.cache.interceptor.CacheEvaluationContext Maven / Gradle / Ivy
/*
* Copyright 2002-2015 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.cache.interceptor;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import org.springframework.context.expression.MethodBasedEvaluationContext;
import org.springframework.core.ParameterNameDiscoverer;
/**
* Cache specific evaluation context that adds a method parameters as SpEL
* variables, in a lazy manner. The lazy nature eliminates unneeded
* parsing of classes byte code for parameter discovery.
*
* Also define a set of "unavailable variables" (i.e. variables that should
* lead to an exception right the way when they are accessed). This can be useful
* to verify a condition does not match even when not all potential variables
* are present.
*
*
To limit the creation of objects, an ugly constructor is used
* (rather then a dedicated 'closure'-like class for deferred execution).
*
* @author Costin Leau
* @author Stephane Nicoll
* @since 3.1
*/
class CacheEvaluationContext extends MethodBasedEvaluationContext {
private final List unavailableVariables;
CacheEvaluationContext(Object rootObject, Method method, Object[] args,
ParameterNameDiscoverer paramDiscoverer) {
super(rootObject, method, args, paramDiscoverer);
this.unavailableVariables = new ArrayList();
}
/**
* Add the specified variable name as unavailable for that context. Any expression trying
* to access this variable should lead to an exception.
* This permits the validation of expressions that could potentially a variable even
* when such variable isn't available yet. Any expression trying to use that variable should
* therefore fail to evaluate.
*/
public void addUnavailableVariable(String name) {
this.unavailableVariables.add(name);
}
/**
* Load the param information only when needed.
*/
@Override
public Object lookupVariable(String name) {
if (this.unavailableVariables.contains(name)) {
throw new VariableNotAvailableException(name);
}
return super.lookupVariable(name);
}
}