DialectFactory.java

/**
 * Copyright (c) 2011-2014, hubin (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>
 * http://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.plugins.pagination;

import static com.baomidou.mybatisplus.enums.DBType.getDBType;

import org.apache.ibatis.session.RowBounds;

import com.baomidou.mybatisplus.exceptions.MybatisPlusException;
import com.baomidou.mybatisplus.plugins.pagination.dialects.DB2Dialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.H2Dialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.HSQLDialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.MySqlDialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.OracleDialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.PostgreDialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.SQLServer2005Dialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.SQLServerDialect;
import com.baomidou.mybatisplus.plugins.pagination.dialects.SQLiteDialect;
import com.baomidou.mybatisplus.toolkit.StringUtils;

/**
 * <p>
 * 分页方言工厂类
 * </p>
 *
 * @author hubin
 * @Date 2016-01-23
 */
public class DialectFactory {

    /**
     * <p>
     * 生成翻页执行 SQL
     * </p>
     *
     * @param page
     *            翻页对象
     * @param buildSql
     *            执行 SQL
     * @param dialectType
     *            方言类型
     * @param dialectClazz
     *            自定义方言实现类
     * @return
     * @throws Exception
     */
    public static String buildPaginationSql(Pagination page, String buildSql, String dialectType, String dialectClazz)
            throws Exception {
        // fix #172, 196
        return getiDialect(dialectType, dialectClazz).buildPaginationSql(buildSql, page.getOffsetCurrent(), page.getSize());
    }

    /**
     * Physical Pagination Interceptor for all the queries with parameter
     * {@link org.apache.ibatis.session.RowBounds}
     *
     * @param rowBounds
     * @param buildSql
     * @param dialectType
     * @param dialectClazz
     * @return
     * @throws Exception
     */
    public static String buildPaginationSql(RowBounds rowBounds, String buildSql, String dialectType, String dialectClazz)
            throws Exception {
        // fix #196
        return getiDialect(dialectType, dialectClazz).buildPaginationSql(buildSql, rowBounds.getOffset(), rowBounds.getLimit());
    }

    /**
     * <p>
     * 获取数据库方言
     * </p>
     *
     * @param dialectType
     *            方言类型
     * @param dialectClazz
     *            自定义方言实现类
     * @return
     * @throws Exception
     */
    private static IDialect getiDialect(String dialectType, String dialectClazz) throws Exception {
        IDialect dialect = null;
        if (StringUtils.isNotEmpty(dialectType)) {
            dialect = getDialectByDbtype(dialectType);
        } else {
            if (StringUtils.isNotEmpty(dialectClazz)) {
                try {
                    Class<?> clazz = Class.forName(dialectClazz);
                    if (IDialect.class.isAssignableFrom(clazz)) {
                        dialect = (IDialect) clazz.newInstance();
                    }
                } catch (ClassNotFoundException e) {
                    throw new MybatisPlusException("Class :" + dialectClazz + " is not found");
                }
            }
        }
        /* 未配置方言则抛出异常 */
        if (dialect == null) {
            throw new MybatisPlusException("The value of the dialect property in mybatis configuration.xml is not defined.");
        }
        return dialect;
    }

    /**
     * <p>
     * 根据数据库类型选择不同分页方言
     * </p>
     *
     * @param dbType
     *            数据库类型
     * @return
     * @throws Exception
     */
    private static IDialect getDialectByDbtype(String dbType) {
        IDialect dialect;
        switch (getDBType(dbType)) {
            case MYSQL:
                dialect = MySqlDialect.INSTANCE;
                break;
            case ORACLE:
                dialect = OracleDialect.INSTANCE;
                break;
            case DB2:
                dialect = DB2Dialect.INSTANCE;
                break;
            case H2:
                dialect = H2Dialect.INSTANCE;
                break;
            case SQLSERVER:
                dialect = SQLServerDialect.INSTANCE;
                break;
            case SQLSERVER2005:
                dialect = SQLServer2005Dialect.INSTANCE;
                break;
            case POSTGRE:
                dialect = PostgreDialect.INSTANCE;
                break;
            case HSQL:
                dialect = HSQLDialect.INSTANCE;
                break;
            case SQLITE:
                dialect = SQLiteDialect.INSTANCE;
                break;
            default:
                throw new MybatisPlusException("The Database's Not Supported! DBType:" + dbType);
        }
        return dialect;
    }

}