MyBatis-Plus - 论 1 个实体类被 N 个DAO 类绑定，导致 MP 特性（逻辑删）失效的解决方案

问题描述

最近遇到一个奇奇怪怪的问题，发现 Mybatis-Plus『逻辑删』特性失效，而且是偶现，有时候可以，有时候又不行。于是开启了 Debug Mybatis-Plus 源码之旅

原因分析

我们接下来重点关注 TableInfoHelper 类

/** Copyright (c) 2011-2020, baomidou (jobob@qq.com).* <p>* 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* <p>* https://www.apache.org/licenses/LICENSE-2.0* <p>* 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.baomidou.mybatisplus.core.metadata;import com.baomidou.mybatisplus.annotation.*;
import com.baomidou.mybatisplus.core.config.GlobalConfig;
import com.baomidou.mybatisplus.core.incrementer.IKeyGenerator;
import com.baomidou.mybatisplus.core.toolkit.*;
import org.apache.ibatis.builder.MapperBuilderAssistant;
import org.apache.ibatis.builder.StaticSqlSource;
import org.apache.ibatis.executor.keygen.KeyGenerator;
import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ResultMap;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.reflection.Reflector;
import org.apache.ibatis.reflection.ReflectorFactory;
import org.apache.ibatis.session.Configuration;
import java.lang.reflect.Field;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import static java.util.stream.Collectors.toList;/*** <p>* 实体类反射表辅助类* </p>** @author hubin sjy* @since 2016-09-09*/
public class TableInfoHelper {private static final Log logger = LogFactory.getLog(TableInfoHelper.class);/*** 储存反射类表信息*/private static final Map<Class<?>, TableInfo> TABLE_INFO_CACHE = new ConcurrentHashMap<>();/*** 默认表主键名称*/private static final String DEFAULT_ID_NAME = "id";/*** <p>* 获取实体映射表信息* </p>** @param clazz 反射实体类* @return 数据库表反射信息*/public static TableInfo getTableInfo(Class<?> clazz) {if (clazz == null|| ReflectionKit.isPrimitiveOrWrapper(clazz)|| clazz == String.class) {return null;}// https://github.com/baomidou/mybatis-plus/issues/299TableInfo tableInfo = TABLE_INFO_CACHE.get(ClassUtils.getUserClass(clazz));if (null != tableInfo) {return tableInfo;}//尝试获取父类缓存Class<?> currentClass = clazz;while (null == tableInfo && Object.class != currentClass) {currentClass = currentClass.getSuperclass();tableInfo = TABLE_INFO_CACHE.get(ClassUtils.getUserClass(currentClass));}if (tableInfo != null) {TABLE_INFO_CACHE.put(ClassUtils.getUserClass(clazz), tableInfo);}return tableInfo;}/*** <p>* 获取所有实体映射表信息* </p>** @return 数据库表反射信息集合*/@SuppressWarnings("unused")public static List<TableInfo> getTableInfos() {return new ArrayList<>(TABLE_INFO_CACHE.values());}/*** <p>* 实体类反射获取表信息【初始化】* </p>** @param clazz 反射实体类* @return 数据库表反射信息*/public synchronized static TableInfo initTableInfo(MapperBuilderAssistant builderAssistant, Class<?> clazz) {TableInfo tableInfo = TABLE_INFO_CACHE.get(clazz);if (tableInfo != null) {if (builderAssistant != null) {tableInfo.setConfiguration(builderAssistant.getConfiguration());}return tableInfo;}/* 没有获取到缓存信息,则初始化 */tableInfo = new TableInfo(clazz);GlobalConfig globalConfig;if (null != builderAssistant) {tableInfo.setCurrentNamespace(builderAssistant.getCurrentNamespace());tableInfo.setConfiguration(builderAssistant.getConfiguration());globalConfig = GlobalConfigUtils.getGlobalConfig(builderAssistant.getConfiguration());} else {// 兼容测试场景globalConfig = GlobalConfigUtils.defaults();}/* 初始化表名相关 */final String[] excludeProperty = initTableName(clazz, globalConfig, tableInfo);List<String> excludePropertyList = excludeProperty != null && excludeProperty.length > 0 ? Arrays.asList(excludeProperty) : Collections.emptyList();/* 初始化字段相关 */initTableFields(clazz, globalConfig, tableInfo, excludePropertyList);/* 放入缓存 */TABLE_INFO_CACHE.put(clazz, tableInfo);/* 缓存 lambda */LambdaUtils.installCache(tableInfo);/* 自动构建 resultMap */tableInfo.initResultMapIfNeed();return tableInfo;}/*** <p>* 初始化 表数据库类型,表名,resultMap* </p>** @param clazz        实体类* @param globalConfig 全局配置* @param tableInfo    数据库表反射信息* @return 需要排除的字段名*/private static String[] initTableName(Class<?> clazz, GlobalConfig globalConfig, TableInfo tableInfo) {/* 数据库全局配置 */GlobalConfig.DbConfig dbConfig = globalConfig.getDbConfig();TableName table = clazz.getAnnotation(TableName.class);String tableName = clazz.getSimpleName();String tablePrefix = dbConfig.getTablePrefix();String schema = dbConfig.getSchema();boolean tablePrefixEffect = true;String[] excludeProperty = null;if (table != null) {if (StringUtils.isNotBlank(table.value())) {tableName = table.value();if (StringUtils.isNotBlank(tablePrefix) && !table.keepGlobalPrefix()) {tablePrefixEffect = false;}} else {tableName = initTableNameWithDbConfig(tableName, dbConfig);}if (StringUtils.isNotBlank(table.schema())) {schema = table.schema();}/* 表结果集映射 */if (StringUtils.isNotBlank(table.resultMap())) {tableInfo.setResultMap(table.resultMap());}tableInfo.setAutoInitResultMap(table.autoResultMap());excludeProperty = table.excludeProperty();} else {tableName = initTableNameWithDbConfig(tableName, dbConfig);}String targetTableName = tableName;if (StringUtils.isNotBlank(tablePrefix) && tablePrefixEffect) {targetTableName = tablePrefix + targetTableName;}if (StringUtils.isNotBlank(schema)) {targetTableName = schema + StringPool.DOT + targetTableName;}tableInfo.setTableName(targetTableName);/* 开启了自定义 KEY 生成器 */if (null != dbConfig.getKeyGenerator()) {tableInfo.setKeySequence(clazz.getAnnotation(KeySequence.class));}return excludeProperty;}/*** 根据 DbConfig 初始化 表名** @param className 类名* @param dbConfig  DbConfig* @return 表名*/private static String initTableNameWithDbConfig(String className, GlobalConfig.DbConfig dbConfig) {String tableName = className;// 开启表名下划线申明if (dbConfig.isTableUnderline()) {tableName = StringUtils.camelToUnderline(tableName);}// 大写命名判断if (dbConfig.isCapitalMode()) {tableName = tableName.toUpperCase();} else {// 首字母小写tableName = StringUtils.firstToLowerCase(tableName);}return tableName;}/*** <p>* 初始化 表主键,表字段* </p>** @param clazz        实体类* @param globalConfig 全局配置* @param tableInfo    数据库表反射信息*/public static void initTableFields(Class<?> clazz, GlobalConfig globalConfig, TableInfo tableInfo, List<String> excludeProperty) {/* 数据库全局配置 */GlobalConfig.DbConfig dbConfig = globalConfig.getDbConfig();ReflectorFactory reflectorFactory = tableInfo.getConfiguration().getReflectorFactory();//TODO @咩咩 有空一起来撸完这反射模块.Reflector reflector = reflectorFactory.findForClass(clazz);List<Field> list = getAllFields(clazz);// 标记是否读取到主键boolean isReadPK = false;// 是否存在 @TableId 注解boolean existTableId = isExistTableId(list);List<TableFieldInfo> fieldList = new ArrayList<>(list.size());for (Field field : list) {if (excludeProperty.contains(field.getName())) {continue;}/* 主键ID 初始化 */if (existTableId) {TableId tableId = field.getAnnotation(TableId.class);if (tableId != null) {if (isReadPK) {throw ExceptionUtils.mpe("@TableId can't more than one in Class: \"%s\".", clazz.getName());} else {isReadPK = initTableIdWithAnnotation(dbConfig, tableInfo, field, tableId, reflector);continue;}}} else if (!isReadPK) {isReadPK = initTableIdWithoutAnnotation(dbConfig, tableInfo, field, reflector);if (isReadPK) {continue;}}/* 有 @TableField 注解的字段初始化 */if (initTableFieldWithAnnotation(dbConfig, tableInfo, fieldList, field)) {continue;}/* 无 @TableField 注解的字段初始化 */fieldList.add(new TableFieldInfo(dbConfig, tableInfo, field));}/* 检查逻辑删除字段只能有最多一个 */Assert.isTrue(fieldList.parallelStream().filter(TableFieldInfo::isLogicDelete).count() < 2L,String.format("@TableLogic can't more than one in Class: \"%s\".", clazz.getName()));/* 字段列表,不可变集合 */tableInfo.setFieldList(Collections.unmodifiableList(fieldList));/* 未发现主键注解，提示警告信息 */if (!isReadPK) {logger.warn(String.format("Can not find table primary key in Class: \"%s\".", clazz.getName()));}}/*** <p>* 判断主键注解是否存在* </p>** @param list 字段列表* @return true 为存在 @TableId 注解;*/public static boolean isExistTableId(List<Field> list) {return list.stream().anyMatch(field -> field.isAnnotationPresent(TableId.class));}/*** <p>* 主键属性初始化* </p>** @param dbConfig  全局配置信息* @param tableInfo 表信息* @param field     字段* @param tableId   注解* @param reflector Reflector*/private static boolean initTableIdWithAnnotation(GlobalConfig.DbConfig dbConfig, TableInfo tableInfo,Field field, TableId tableId, Reflector reflector) {boolean underCamel = tableInfo.isUnderCamel();final String property = field.getName();if (field.getAnnotation(TableField.class) != null) {logger.warn(String.format("This \"%s\" is the table primary key by @TableId annotation in Class: \"%s\",So @TableField annotation will not work!",property, tableInfo.getEntityType().getName()));}/* 主键策略（ 注解 > 全局 ） */// 设置 Sequence 其他策略无效if (IdType.NONE == tableId.type()) {tableInfo.setIdType(dbConfig.getIdType());} else {tableInfo.setIdType(tableId.type());}/* 字段 */String column = property;if (StringUtils.isNotBlank(tableId.value())) {column = tableId.value();} else {// 开启字段下划线申明if (underCamel) {column = StringUtils.camelToUnderline(column);}// 全局大写命名if (dbConfig.isCapitalMode()) {column = column.toUpperCase();}}tableInfo.setKeyRelated(checkRelated(underCamel, property, column)).setKeyColumn(column).setKeyProperty(property).setKeyType(reflector.getGetterType(property));return true;}/*** <p>* 主键属性初始化* </p>** @param tableInfo 表信息* @param field     字段* @param reflector Reflector* @return true 继续下一个属性判断，返回 continue;*/private static boolean initTableIdWithoutAnnotation(GlobalConfig.DbConfig dbConfig, TableInfo tableInfo,Field field, Reflector reflector) {final String property = field.getName();if (DEFAULT_ID_NAME.equalsIgnoreCase(property)) {if (field.getAnnotation(TableField.class) != null) {logger.warn(String.format("This \"%s\" is the table primary key by default name for `id` in Class: \"%s\",So @TableField will not work!",property, tableInfo.getEntityType().getName()));}String column = property;if (dbConfig.isCapitalMode()) {column = column.toUpperCase();}tableInfo.setKeyRelated(checkRelated(tableInfo.isUnderCamel(), property, column)).setIdType(dbConfig.getIdType()).setKeyColumn(column).setKeyProperty(property).setKeyType(reflector.getGetterType(property));return true;}return false;}/*** <p>* 字段属性初始化* </p>** @param dbConfig  数据库全局配置* @param tableInfo 表信息* @param fieldList 字段列表* @return true 继续下一个属性判断，返回 continue;*/private static boolean initTableFieldWithAnnotation(GlobalConfig.DbConfig dbConfig, TableInfo tableInfo,List<TableFieldInfo> fieldList, Field field) {/* 获取注解属性，自定义字段 */TableField tableField = field.getAnnotation(TableField.class);if (null == tableField) {return false;}fieldList.add(new TableFieldInfo(dbConfig, tableInfo, field, tableField));return true;}/*** <p>* 判定 related 的值* </p>** @param underCamel 驼峰命名* @param property   属性名* @param column     字段名* @return related*/public static boolean checkRelated(boolean underCamel, String property, String column) {if (StringUtils.isNotColumnName(column)) {// 首尾有转义符,手动在注解里设置了转义符,去除掉转义符column = column.substring(1, column.length() - 1);}String propertyUpper = property.toUpperCase(Locale.ENGLISH);String columnUpper = column.toUpperCase(Locale.ENGLISH);if (underCamel) {// 开启了驼峰并且 column 包含下划线return !(propertyUpper.equals(columnUpper) ||propertyUpper.equals(columnUpper.replace(StringPool.UNDERSCORE, StringPool.EMPTY)));} else {// 未开启驼峰,直接判断 property 是否与 column 相同(全大写)return !propertyUpper.equals(columnUpper);}}/*** <p>* 获取该类的所有属性列表* </p>** @param clazz 反射类* @return 属性集合*/public static List<Field> getAllFields(Class<?> clazz) {List<Field> fieldList = ReflectionKit.getFieldList(ClassUtils.getUserClass(clazz));return fieldList.stream().filter(field -> {/* 过滤注解非表字段属性 */TableField tableField = field.getAnnotation(TableField.class);return (tableField == null || tableField.exist());}).collect(toList());}public static KeyGenerator genKeyGenerator(String baseStatementId, TableInfo tableInfo, MapperBuilderAssistant builderAssistant) {IKeyGenerator keyGenerator = GlobalConfigUtils.getKeyGenerator(builderAssistant.getConfiguration());if (null == keyGenerator) {throw new IllegalArgumentException("not configure IKeyGenerator implementation class.");}Configuration configuration = builderAssistant.getConfiguration();//TODO 这里不加上builderAssistant.getCurrentNamespace()的会导致com.baomidou.mybatisplus.core.parser.SqlParserHelper.getSqlParserInfo越(chu)界(gui)String id = builderAssistant.getCurrentNamespace() + StringPool.DOT + baseStatementId + SelectKeyGenerator.SELECT_KEY_SUFFIX;ResultMap resultMap = new ResultMap.Builder(builderAssistant.getConfiguration(), id, tableInfo.getKeyType(), new ArrayList<>()).build();MappedStatement mappedStatement = new MappedStatement.Builder(builderAssistant.getConfiguration(), id,new StaticSqlSource(configuration, keyGenerator.executeSql(tableInfo.getKeySequence().value())), SqlCommandType.SELECT).keyProperty(tableInfo.getKeyProperty()).resultMaps(Collections.singletonList(resultMap)).build();configuration.addMappedStatement(mappedStatement);return new SelectKeyGenerator(mappedStatement, true);}
}

注意这里的 initTableInfo 方法，这里面是所有 MapperScan 扫码 DAO 类时候会初始化的必经之路，不过出问题的根本也就是在这个方法里

/*** <p>* 实体类反射获取表信息【初始化】* </p>** @param clazz 反射实体类* @return 数据库表反射信息*/
public synchronized static TableInfo initTableInfo(MapperBuilderAssistant builderAssistant, Class<?> clazz) {TableInfo tableInfo = TABLE_INFO_CACHE.get(clazz);if (tableInfo != null) {if (builderAssistant != null) {tableInfo.setConfiguration(builderAssistant.getConfiguration());}return tableInfo;}/* 没有获取到缓存信息,则初始化 */tableInfo = new TableInfo(clazz);GlobalConfig globalConfig;if (null != builderAssistant) {tableInfo.setCurrentNamespace(builderAssistant.getCurrentNamespace());tableInfo.setConfiguration(builderAssistant.getConfiguration());globalConfig = GlobalConfigUtils.getGlobalConfig(builderAssistant.getConfiguration());} else {// 兼容测试场景globalConfig = GlobalConfigUtils.defaults();}/* 初始化表名相关 */final String[] excludeProperty = initTableName(clazz, globalConfig, tableInfo);List<String> excludePropertyList = excludeProperty != null && excludeProperty.length > 0 ? Arrays.asList(excludeProperty) : Collections.emptyList();/* 初始化字段相关 */initTableFields(clazz, globalConfig, tableInfo, excludePropertyList);/* 放入缓存 */TABLE_INFO_CACHE.put(clazz, tableInfo);/* 缓存 lambda */LambdaUtils.installCache(tableInfo);/* 自动构建 resultMap */tableInfo.initResultMapIfNeed();return tableInfo;
}

我把关键核心代码显示出来，其他忽略掉先，单单看下面代码意味着什么呢？
简单理解：TABLE_INFO_CACHE 集合存放实体类和DAO类的映射关系，KV结构（K - 实体类全限定名，V - DAO 类绑定数据源的相关信息）
如果按照这个理解，那显而易见，如果说有 1 个实体类，被多个 DAO 绑定的话，那一定会被扫到初始化时，后来者会覆盖前者，这样就导致了只有后者的 DAO 拥有 MP 特性，前者就会失去一些 MP 特性，但是经测试基本的 MyBatis 特性有些具备，反正就会功能不完整

private static final Map<Class<?>, TableInfo> TABLE_INFO_CACHE = new ConcurrentHashMap<>();public synchronized static TableInfo initTableInfo(MapperBuilderAssistant builderAssistant, Class<?> clazz) {TableInfo tableInfo = TABLE_INFO_CACHE.get(clazz);if (tableInfo != null) {if (builderAssistant != null) {tableInfo.setConfiguration(builderAssistant.getConfiguration());}return tableInfo;}/* 没有获取到缓存信息,则初始化 */// .../* 放入缓存 */TABLE_INFO_CACHE.put(clazz, tableInfo);// ...return tableInfo;
}