001/*
002 *  Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
003 *  <p>
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *  <p>
008 *  http://www.apache.org/licenses/LICENSE-2.0
009 *  <p>
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package com.mybatisflex.core.util;
017
018import com.mybatisflex.core.exception.FlexExceptions;
019import com.mybatisflex.core.query.QueryColumn;
020import com.mybatisflex.core.table.TableInfo;
021import com.mybatisflex.core.table.TableInfoFactory;
022
023import java.io.Serializable;
024import java.lang.invoke.SerializedLambda;
025import java.lang.reflect.Method;
026import java.util.Map;
027import java.util.concurrent.ConcurrentHashMap;
028
029public class LambdaUtil {
030
031    private LambdaUtil() {
032    }
033
034    private static final Map<Class<?>, SerializedLambda> lambdaMap = new ConcurrentHashMap<>();
035    private static final Map<String, Class<?>> classMap = new ConcurrentHashMap<>();
036
037    public static <T> String getFieldName(LambdaGetter<T> getter) {
038        SerializedLambda lambda = getSerializedLambda(getter);
039        String methodName = lambda.getImplMethodName();
040        return StringUtil.methodToProperty(methodName);
041    }
042
043
044    public static <T> Class<?> getImplClass(LambdaGetter<T> getter) {
045        SerializedLambda lambda = getSerializedLambda(getter);
046        return getImplClass(lambda, getter.getClass().getClassLoader());
047    }
048
049
050    public static <T> String getAliasName(LambdaGetter<T> getter, boolean withPrefix) {
051        QueryColumn queryColumn = getQueryColumn(getter);
052        if (queryColumn != null) {
053            String alias = StringUtil.isNotBlank(queryColumn.getAlias()) ? queryColumn.getAlias() : queryColumn.getName();
054            return withPrefix ? queryColumn.getTable().getName() + "$" + alias : alias;
055        }
056        return getFieldName(getter);
057    }
058
059
060    public static <T> QueryColumn getQueryColumn(LambdaGetter<T> getter) {
061        ClassLoader classLoader = getter.getClass().getClassLoader();
062        SerializedLambda lambda = getSerializedLambda(getter);
063        String methodName = lambda.getImplMethodName();
064        Class<?> entityClass = getImplClass(lambda, classLoader);
065        TableInfo tableInfo = TableInfoFactory.ofEntityClass(entityClass);
066        return tableInfo.getQueryColumnByProperty(StringUtil.methodToProperty(methodName));
067    }
068
069
070    private static SerializedLambda getSerializedLambda(Serializable getter) {
071        return MapUtil.computeIfAbsent(lambdaMap, getter.getClass(), aClass -> {
072            try {
073                Method method = getter.getClass().getDeclaredMethod("writeReplace");
074                method.setAccessible(Boolean.TRUE);
075                return (SerializedLambda) method.invoke(getter);
076            } catch (Exception e) {
077                throw new RuntimeException(e);
078            }
079        });
080    }
081
082
083    private static Class<?> getImplClass(SerializedLambda lambda, ClassLoader classLoader) {
084        String implClass = getImplClassName(lambda);
085        return MapUtil.computeIfAbsent(classMap, implClass, s -> {
086            try {
087                return Class.forName(s.replace("/", "."), true, classLoader);
088            } catch (ClassNotFoundException e) {
089                throw FlexExceptions.wrap(e);
090            }
091        });
092    }
093
094    private static String getImplClassName(SerializedLambda lambda) {
095        String type = lambda.getInstantiatedMethodType();
096        return type.substring(2, type.indexOf(";"));
097    }
098
099}