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.dialect;
017
018
019import com.mybatisflex.core.FlexGlobalConfig;
020import com.mybatisflex.core.util.ObjectUtil;
021import org.apache.ibatis.util.MapUtil;
022
023import java.util.EnumMap;
024import java.util.Map;
025
026/**
027 * 方言工厂类，用于创建方言
028 */
029public class DialectFactory {
030
031    /**
032     * 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
033     * 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
034     * 此 map 中，用于覆盖系统的方言实现
035     */
036    private static Map<DbType, IDialect> dialectMap = new EnumMap<>(DbType.class);
037
038    /**
039     * 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
040     */
041    private static ThreadLocal<DbType> dbTypeThreadLocal = new ThreadLocal<>();
042
043
044    /**
045     * 获取方言
046     *
047     * @return IDialect
048     */
049    public static IDialect getDialect() {
050        DbType dbType = ObjectUtil.requireNonNullElse(dbTypeThreadLocal.get(), FlexGlobalConfig.getDefaultConfig().getDbType());
051        return MapUtil.computeIfAbsent(dialectMap, dbType, DialectFactory::createDialect);
052    }
053
054    /**
055     * 设置当前线程的 dbType
056     *
057     * @param dbType
058     */
059    public static void setHintDbType(DbType dbType) {
060        dbTypeThreadLocal.set(dbType);
061    }
062
063    /**
064     * 获取当前线程的 dbType
065     *
066     * @return dbType
067     */
068    public static DbType getHintDbType() {
069        return dbTypeThreadLocal.get();
070    }
071
072
073    /**
074     * 清除当前线程的 dbType
075     */
076    public static void clearHintDbType() {
077        dbTypeThreadLocal.remove();
078    }
079
080
081    /**
082     * 可以为某个 dbType 注册（新增或覆盖）自己的方言
083     *
084     * @param dbType  数据库类型
085     * @param dialect 方言的实现
086     */
087    public static void registerDialect(DbType dbType, IDialect dialect) {
088        dialectMap.put(dbType, dialect);
089    }
090
091
092    private static IDialect createDialect(DbType dbType) {
093        switch (dbType) {
094            case MYSQL:
095            case H2:
096            case MARIADB:
097            case GBASE:
098            case OSCAR:
099            case XUGU:
100            case CLICK_HOUSE:
101            case OCEAN_BASE:
102            case CUBRID:
103            case GOLDILOCKS:
104            case CSIIDB:
105                return new CommonsDialectImpl(KeywordWrap.BACKQUOTE, LimitOffsetProcesser.MYSQL);
106            case ORACLE:
107            case DM:
108            case GAUSS:
109                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.ORACLE);
110            case POSTGRE_SQL:
111            case SQLITE:
112            case HSQL:
113            case KINGBASE_ES:
114            case PHOENIX:
115            case SAP_HANA:
116            case IMPALA:
117            case HIGH_GO:
118            case VERTICA:
119            case REDSHIFT:
120            case OPENGAUSS:
121            case TDENGINE:
122            case UXDB:
123                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.POSTGRESQL);
124            case ORACLE_12C:
125            case FIREBIRD:
126                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.DERBY);
127            case SQLSERVER:
128                return new CommonsDialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcesser.DERBY);
129            case SQLSERVER_2005:
130                return new CommonsDialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcesser.DB2);
131            case INFORMIX:
132                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.INFORMIX);
133            case DB2:
134                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.DB2);
135            case SYBASE:
136                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcesser.SYBASE);
137            default:
138                return new CommonsDialectImpl();
139        }
140    }
141}