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.dialect.impl.CommonsDialectImpl;
021import com.mybatisflex.core.dialect.impl.DmDialect;
022import com.mybatisflex.core.dialect.impl.OracleDialect;
023import com.mybatisflex.core.util.ObjectUtil;
024import org.apache.ibatis.util.MapUtil;
025
026import java.util.EnumMap;
027import java.util.Map;
028
029/**
030 * 方言工厂类，用于创建方言
031 */
032public class DialectFactory {
033
034    private DialectFactory() {
035    }
036
037    /**
038     * 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
039     * 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
040     * 此 map 中，用于覆盖系统的方言实现
041     */
042    private static final Map<DbType, IDialect> dialectMap = new EnumMap<>(DbType.class);
043
044    /**
045     * 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
046     */
047    private static final ThreadLocal<DbType> dbTypeThreadLocal = new ThreadLocal<>();
048
049
050    /**
051     * 获取方言
052     *
053     * @return IDialect
054     */
055    public static IDialect getDialect() {
056        DbType dbType = ObjectUtil.requireNonNullElse(dbTypeThreadLocal.get(), FlexGlobalConfig.getDefaultConfig().getDbType());
057        return MapUtil.computeIfAbsent(dialectMap, dbType, DialectFactory::createDialect);
058    }
059
060    /**
061     * 设置当前线程的 dbType
062     *
063     * @param dbType
064     */
065    public static void setHintDbType(DbType dbType) {
066        dbTypeThreadLocal.set(dbType);
067    }
068
069    /**
070     * 获取当前线程的 dbType
071     *
072     * @return dbType
073     */
074    public static DbType getHintDbType() {
075        return dbTypeThreadLocal.get();
076    }
077
078
079    /**
080     * 清除当前线程的 dbType
081     */
082    public static void clearHintDbType() {
083        dbTypeThreadLocal.remove();
084    }
085
086
087    /**
088     * 可以为某个 dbType 注册（新增或覆盖）自己的方言
089     *
090     * @param dbType  数据库类型
091     * @param dialect 方言的实现
092     */
093    public static void registerDialect(DbType dbType, IDialect dialect) {
094        dialectMap.put(dbType, dialect);
095    }
096
097
098    private static IDialect createDialect(DbType dbType) {
099        switch (dbType) {
100            case MYSQL:
101            case H2:
102            case MARIADB:
103            case GBASE:
104            case OSCAR:
105            case XUGU:
106            case OCEAN_BASE:
107            case CUBRID:
108            case GOLDILOCKS:
109            case CSIIDB:
110            case HIVE:
111            case DORIS:
112                return new CommonsDialectImpl(KeywordWrap.BACK_QUOTE, LimitOffsetProcessor.MYSQL);
113            case CLICK_HOUSE:
114                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.MYSQL);
115            case DM:
116                return new DmDialect();
117            case ORACLE:
118                return new OracleDialect();
119            case GAUSS:
120                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.ORACLE);
121            case POSTGRE_SQL:
122            case SQLITE:
123            case HSQL:
124            case KINGBASE_ES:
125            case PHOENIX:
126            case SAP_HANA:
127            case IMPALA:
128            case HIGH_GO:
129            case VERTICA:
130            case REDSHIFT:
131            case OPENGAUSS:
132            case UXDB:
133            case LEALONE:
134                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.POSTGRESQL);
135            case TDENGINE:
136                return new CommonsDialectImpl(KeywordWrap.BACK_QUOTE, LimitOffsetProcessor.POSTGRESQL);
137            case ORACLE_12C:
138                return new OracleDialect(LimitOffsetProcessor.DERBY);
139            case FIREBIRD:
140            case DB2:
141                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.DERBY);
142            case SQLSERVER:
143                return new CommonsDialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcessor.SQLSERVER);
144            case SQLSERVER_2005:
145                return new CommonsDialectImpl(KeywordWrap.SQUARE_BRACKETS, LimitOffsetProcessor.SQLSERVER_2005);
146            case INFORMIX:
147                return new CommonsDialectImpl(KeywordWrap.NONE, LimitOffsetProcessor.INFORMIX);
148            case SINODB:
149                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.SINODB);
150            case SYBASE:
151                return new CommonsDialectImpl(KeywordWrap.DOUBLE_QUOTATION, LimitOffsetProcessor.SYBASE);
152            default:
153                return new CommonsDialectImpl();
154        }
155    }
156
157}