java 8 根據方法引用獲取對應的屬性字段

package com.jake.test;

import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
import java.beans.Introspector;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class ReflectionUtil {
    private static final Map<SerializableFunction<?, ?>, Field> CACHE = new ConcurrentHashMap<>();

    public static <T, R> String getFieldName(SerializableFunction<T, R> function) {
        Field field = ReflectionUtil.getField(function);
        return field.getName();
    }

    public static Field getField(SerializableFunction<?, ?> function) {
        return CACHE.computeIfAbsent(function, ReflectionUtil::findField);
    }

    public static Field findField(SerializableFunction<?, ?> function) {
        Field field = null;
        String fieldName = null;
        try {
            // 第1步 獲取SerializedLambda
            Method method = function.getClass().getDeclaredMethod("writeReplace");
            method.setAccessible(Boolean.TRUE);
            SerializedLambda serializedLambda = (SerializedLambda) method.invoke(function);
            // 第2步 implMethodName 即為Field對應的Getter方法名
            String implMethodName = serializedLambda.getImplMethodName();
            if (implMethodName.startsWith("get") && implMethodName.length() > 3) {
                fieldName = Introspector.decapitalize(implMethodName.substring(3));

            } else if (implMethodName.startsWith("is") && implMethodName.length() > 2) {
                fieldName = Introspector.decapitalize(implMethodName.substring(2));
            } else if (implMethodName.startsWith("lambda$")) {
                throw new IllegalArgumentException("SerializableFunction不能傳遞lambda表達式,只能使用方法引用");

            } else {
                throw new IllegalArgumentException(implMethodName + "不是Getter方法引用");
            }
            // 第3步 獲取的Class是字符串，並且包名是“/”分割，需要替換成“.”，才能獲取到對應的Class對象
            String declaredClass = serializedLambda.getImplClass().replace("/", ".");
            Class<?> aClass = Class.forName(declaredClass, false, ClassUtils.getDefaultClassLoader());

            // 第4步  Spring 中的反射工具類獲取Class中定義的Field
            field = ReflectionUtils.findField(aClass, fieldName);

        } catch (Exception e) {
            e.printStackTrace();
        }
        // 第5步 如果沒有找到對應的字段應該拋出異常
        if (field != null) {
            return field;
        }
        throw new NoSuchFieldError(fieldName);
    }
}

參考