001/*
002 *  Copyright (c) 2022-2025, 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.dialect;
017
018
019import com.mybatisflex.core.FlexGlobalConfig;
020import com.mybatisflex.core.dialect.impl.*;
021import com.mybatisflex.core.util.MapUtil;
022import com.mybatisflex.core.util.ObjectUtil;
023
024import java.util.EnumMap;
025import java.util.Map;
026
027/**
028 * 方言工厂类，用于创建方言
029 */
030public class DialectFactory {
031
032    private DialectFactory() {
033    }
034
035    /**
036     * 数据库类型和方言的映射关系，可以通过其读取指定的方言，亦可能通过其扩展其他方言
037     * 比如，在 mybatis-flex 实现的方言中有 bug 或者 有自己的独立实现，可以添加自己的方言实现到
038     * 此 map 中，用于覆盖系统的方言实现
039     */
040    private static final Map<DbType, IDialect> dialectMap = new EnumMap<>(DbType.class);
041    /**
042     * 通过设置当前线程的数据库类型，以达到在代码执行时随时切换方言的功能
043     */
044    private static final ThreadLocal<DbType> dbTypeThreadLocal = new ThreadLocal<>();
045
046    /**
047     * 获取方言
048     *
049     * @return IDialect
050     */
051    public static IDialect getDialect() {
052        DbType dbType = ObjectUtil.requireNonNullElse(dbTypeThreadLocal.get(),
053            FlexGlobalConfig.getDefaultConfig().getDbType());
054        return MapUtil.computeIfAbsent(dialectMap, dbType, DialectFactory::createDialect);
055    }
056
057    /**
058     * 设置当前线程的 dbType
059     *
060     * @param dbType
061     */
062    public static void setHintDbType(DbType dbType) {
063        dbTypeThreadLocal.set(dbType);
064    }
065
066    /**
067     * 获取当前线程的 dbType
068     *
069     * @return dbType
070     */
071    public static DbType getHintDbType() {
072        return dbTypeThreadLocal.get();
073    }
074
075
076    /**
077     * 清除当前线程的 dbType
078     */
079    public static void clearHintDbType() {
080        dbTypeThreadLocal.remove();
081    }
082
083
084    /**
085     * 可以为某个 dbType 注册（新增或覆盖）自己的方言
086     *
087     * @param dbType  数据库类型
088     * @param dialect 方言的实现
089     */
090    public static void registerDialect(DbType dbType, IDialect dialect) {
091        dialectMap.put(dbType, dialect);
092    }
093
094
095    private static IDialect createDialect(DbType dbType) {
096        switch (dbType) {
097            case MYSQL:
098            case H2:
099            case MARIADB:
100            case GBASE:
101            case OSCAR:
102            case XUGU:
103            case OCEAN_BASE:
104            case CUBRID:
105            case GOLDILOCKS:
106            case CSIIDB:
107            case HIVE:
108            case DORIS:
109            case GOLDENDB:
110            case SUNDB:
111            case YASDB:
112                return new CommonsDialectImpl(KeywordWrap.BACK_QUOTE, LimitOffsetProcessor.MYSQL);
113            case CLICK_HOUSE:
114                return new ClickhouseDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.MYSQL);
115            case GBASE_8S:
116                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.MYSQL);
117            case DM:
118                return new DmDialect();
119            case ORACLE:
120                return new OracleDialect();
121            case GAUSS:
122                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.ORACLE);
123            case POSTGRE_SQL:
124            case SQLITE:
125            case HSQL:
126            case KINGBASE_ES:
127            case PHOENIX:
128            case SAP_HANA:
129            case IMPALA:
130            case HIGH_GO:
131            case VERTICA:
132            case REDSHIFT:
133            case OPENGAUSS:
134            case UXDB:
135            case LEALONE:
136            case DUCKDB:
137            case GBASE_8C:
138            case GBASE_8S_PG:
139            case VASTBASE:
140            case TRINO:
141            case PRESTO:
142                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.POSTGRESQL);
143            case TDENGINE:
144                return new CommonsDialectImpl(KeywordWrap.BACK_QUOTE, LimitOffsetProcessor.POSTGRESQL);
145            case ORACLE_12C:
146                return new OracleDialect(LimitOffsetProcessor.DERBY);
147            case FIREBIRD:
148            case DB2:
149                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.DERBY);
150            case DB2_1005:
151                return new DB2105Dialect(KeywordWrap.NONE, DB2105Dialect.DB2105LimitOffsetProcessor.DB2105);
152            case SQLSERVER:
153                return new SqlserverDialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcessor.SQLSERVER);
154            case SQLSERVER_2005:
155                return new Sqlserver2005DialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcessor.SQLSERVER_2005);
156            case INFORMIX:
157                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.INFORMIX);
158            case SINODB:
159                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.SINODB);
160            case SYBASE:
161                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.SYBASE);
162            default:
163                return new CommonsDialectImpl();
164        }
165    }
166
167}