com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor Maven / Gradle / Ivy

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/*
 * Copyright (c) 2011-2022, baomidou ([email protected]).
 *
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.extension.plugins.inner;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.core.toolkit.*;
import com.baomidou.mybatisplus.extension.plugins.pagination.DialectFactory;
import com.baomidou.mybatisplus.extension.plugins.pagination.DialectModel;
import com.baomidou.mybatisplus.extension.plugins.pagination.dialects.IDialect;
import com.baomidou.mybatisplus.extension.toolkit.JdbcUtils;
import com.baomidou.mybatisplus.extension.toolkit.PropertyMapper;
import com.baomidou.mybatisplus.extension.toolkit.SqlParserUtils;
import lombok.Data;
import lombok.NoArgsConstructor;
import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.Alias;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.schema.Table;
import net.sf.jsqlparser.statement.select.*;
import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ResultMap;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

import java.sql.SQLException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

/**
 * 分页拦截器
 * 
 * 默认对 left join 进行优化,虽然能优化count,但是加上分页的话如果1对多本身结果条数就是不正确的
 *
 * @author hubin
 * @since 3.4.0
 */
@Data
@NoArgsConstructor
@SuppressWarnings({"rawtypes"})
public class PaginationInnerInterceptor implements InnerInterceptor {
    /**
     * 获取jsqlparser中count的SelectItem
     */
    protected static final List COUNT_SELECT_ITEM = Collections.singletonList(
        new SelectExpressionItem(new Column().withColumnName("COUNT(*)")).withAlias(new Alias("total"))
    );
    protected static final Map countMsCache = new ConcurrentHashMap<>();
    protected final Log logger = LogFactory.getLog(this.getClass());


    /**
     * 溢出总页数后是否进行处理
     */
    protected boolean overflow;
    /**
     * 单页分页条数限制
     */
    protected Long maxLimit;
    /**
     * 数据库类型
     * 

     * 查看 {@link #findIDialect(Executor)} 逻辑
     */
    private DbType dbType;
    /**
     * 方言实现类
     * 

     * 查看 {@link #findIDialect(Executor)} 逻辑
     */
    private IDialect dialect;
    /**
     * 生成 countSql 优化掉 join
     * 现在只支持 left join
     *
     * @since 3.4.2
     */
    protected boolean optimizeJoin = true;

    public PaginationInnerInterceptor(DbType dbType) {
        this.dbType = dbType;
    }

    public PaginationInnerInterceptor(IDialect dialect) {
        this.dialect = dialect;
    }

    /**
     * 这里进行count,如果count为0这返回false(就是不再执行sql了)
     */
    @Override
    public boolean willDoQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
        IPage page = ParameterUtils.findPage(parameter).orElse(null);
        if (page == null || page.getSize() < 0 || !page.searchCount()) {
            return true;
        }

        BoundSql countSql;
        MappedStatement countMs = buildCountMappedStatement(ms, page.countId());
        if (countMs != null) {
            countSql = countMs.getBoundSql(parameter);
        } else {
            countMs = buildAutoCountMappedStatement(ms);
            String countSqlStr = autoCountSql(page, boundSql.getSql());
            PluginUtils.MPBoundSql mpBoundSql = PluginUtils.mpBoundSql(boundSql);
            countSql = new BoundSql(countMs.getConfiguration(), countSqlStr, mpBoundSql.parameterMappings(), parameter);
            PluginUtils.setAdditionalParameter(countSql, mpBoundSql.additionalParameters());
        }

        CacheKey cacheKey = executor.createCacheKey(countMs, parameter, rowBounds, countSql);
        List