com.livk.commons.expression.CacheExpressionResolver Maven / Gradle / Ivy
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/*
* Copyright 2021-2024 spring-boot-extension 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 com.livk.commons.expression;
import com.livk.commons.util.ObjectUtils;
import lombok.Setter;
import org.springframework.core.env.Environment;
import org.springframework.expression.ExpressionException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* 使用缓存机制，减少重新构建EXPRESSION表达式的次数
*
* @param 表达式泛型
* @author livk
* @see com.livk.commons.expression.aviator.AviatorExpressionResolver
* @see Environment
*/
public abstract class CacheExpressionResolver extends AbstractExpressionResolver {
private final Map expressionCache = new ConcurrentHashMap<>(256);
@Setter
private Environment environment;
@Override
public T evaluate(String value, Context context, Class returnType) {
if (ObjectUtils.isEmpty(value)) {
return null;
}
try {
value = wrapIfNecessary(value);
if (environment != null) {
value = environment.resolvePlaceholders(value);
}
EXPRESSION expression = this.expressionCache.get(value);
if (expression == null) {
expression = compile(value);
this.expressionCache.put(value, expression);
}
return calculate(expression, context, returnType);
}
catch (Throwable ex) {
throw new ExpressionException("Expression parsing failed", ex);
}
}
/**
* 对表达式进行数据包装，如果有必要
* @param expression 表达式
* @return 包装后的表达式 string
*/
protected String wrapIfNecessary(String expression) {
return expression;
}
/**
* 对表达式进行处理生成EXPRESSION
* @param value 表达式
* @return EXPRESSION expression
* @throws Throwable the throwable
*/
protected abstract EXPRESSION compile(String value) throws Throwable;
/**
* 表达式计算
* @param 泛型
* @param expression 表达式
* @param context 环境上下文
* @param returnType 返回类型
* @return T
* @throws Throwable the throwable
*/
protected abstract T calculate(EXPRESSION expression, Context context, Class returnType) throws Throwable;
}