如何通过Spring提供的EL表达式执行bean的属性或方法？

如何通过Spring提供的EL表达式执行bean的属性或方法？

关键两个bean：

org.springframework.expression.Expression

org.springframework.expression.spel.support.StandardEvaluationContext

实例：

import cn.hutool.extra.spring.SpringUtil;
import org.springframework.beans.factory.BeanExpressionException;
import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.context.expression.*;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.ParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.expression.spel.support.StandardTypeConverter;
import org.springframework.expression.spel.support.StandardTypeLocator;
import org.springframework.lang.NonNull;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.context.request.RequestScope;import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;@Component
public final class CustomSpringBeanExpressionEvaluator {private final Map<String, Expression> expressionCache = new ConcurrentHashMap<>(256);private final Map<BeanExpressionContext, StandardEvaluationContext> evaluationCache = new ConcurrentHashMap<>(8);private final ExpressionParser parser = new SpelExpressionParser();private BeanExpressionContext beanExpressionContext;public static Object evaluate(@NonNull String expression) {return SpringUtil.getBean(CustomSpringBeanExpressionEvaluator.class).doEvaluate(expression);}/*** SpringEL表达式解析** @param expression - EL表达式*/public Object doEvaluate(@NonNull String expression) {if (!StringUtils.hasLength(expression)) {return expression;}try {Expression expr = this.expressionCache.get(expression);if (expr == null) {expr = this.parser.parseExpression(expression, this.beanExpressionParserContext);this.expressionCache.put(expression, expr);}if (this.beanExpressionContext == null) {this.beanExpressionContext = new BeanExpressionContext(SpringUtil.getConfigurableBeanFactory(), new RequestScope());}StandardEvaluationContext sec = this.evaluationCache.get(beanExpressionContext);if (sec == null) {sec = new StandardEvaluationContext(beanExpressionContext);sec.addPropertyAccessor(new BeanExpressionContextAccessor());sec.addPropertyAccessor(new BeanFactoryAccessor());sec.addPropertyAccessor(new MapAccessor());sec.addPropertyAccessor(new EnvironmentAccessor());sec.setBeanResolver(new BeanFactoryResolver(beanExpressionContext.getBeanFactory()));sec.setTypeLocator(new StandardTypeLocator(beanExpressionContext.getBeanFactory().getBeanClassLoader()));sec.setTypeConverter(new StandardTypeConverter(() -> {ConversionService cs = beanExpressionContext.getBeanFactory().getConversionService();return (cs != null ? cs : DefaultConversionService.getSharedInstance());}));this.evaluationCache.put(beanExpressionContext, sec);}return expr.getValue(sec);} catch (Throwable ex) {throw new BeanExpressionException("Expression parsing failed", ex);}}private final ParserContext beanExpressionParserContext = new ParserContext() {@Overridepublic boolean isTemplate() {return true;}@Overridepublic String getExpressionPrefix() {return "#{";}@Overridepublic String getExpressionSuffix() {return "}";}};
}

使用示例

CustomSpringBeanExpressionEvaluator.evaluate("#{bean.fieldName}")

CustomSpringBeanExpressionEvaluator.evaluate("#{bean.methodName}")