Java tutorial
/** * Copyright (c) 2011-2020, 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; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.Properties; import org.apache.ibatis.executor.statement.StatementHandler; 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.SqlCommandType; import org.apache.ibatis.plugin.Interceptor; import org.apache.ibatis.plugin.Intercepts; import org.apache.ibatis.plugin.Invocation; import org.apache.ibatis.plugin.Plugin; import org.apache.ibatis.plugin.Signature; import org.apache.ibatis.reflection.MetaObject; import org.apache.ibatis.reflection.SystemMetaObject; import org.apache.ibatis.scripting.defaults.DefaultParameterHandler; import org.apache.ibatis.session.RowBounds; import com.baomidou.mybatisplus.MybatisDefaultParameterHandler; import com.baomidou.mybatisplus.entity.CountOptimize; import com.baomidou.mybatisplus.plugins.pagination.DialectFactory; import com.baomidou.mybatisplus.plugins.pagination.Pagination; import com.baomidou.mybatisplus.toolkit.JdbcUtils; import com.baomidou.mybatisplus.toolkit.PluginUtils; import com.baomidou.mybatisplus.toolkit.SqlUtils; import com.baomidou.mybatisplus.toolkit.StringUtils; /** * <p> * * </p> * * @author hubin * @Date 2016-01-23 */ @Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class, Integer.class }) }) public class PaginationInterceptor implements Interceptor { private static final Log logger = LogFactory.getLog(PaginationInterceptor.class); /* */ private boolean overflowCurrent = false; /* ???? ?????? */ private boolean dynamicDataSource = false; /* Count? */ private String optimizeType = "default"; /* */ private String dialectType; /* */ private String dialectClazz; /** * Physical Pagination Interceptor for all the queries with parameter {@link org.apache.ibatis.session.RowBounds} */ public Object intercept(Invocation invocation) throws Throwable { StatementHandler statementHandler = (StatementHandler) PluginUtils.realTarget(invocation.getTarget()); MetaObject metaStatementHandler = SystemMetaObject.forObject(statementHandler); // ?SELECT? MappedStatement mappedStatement = (MappedStatement) metaStatementHandler .getValue("delegate.mappedStatement"); if (!SqlCommandType.SELECT.equals(mappedStatement.getSqlCommandType())) { return invocation.proceed(); } RowBounds rowBounds = (RowBounds) metaStatementHandler.getValue("delegate.rowBounds"); /* ??? */ if (rowBounds == null || rowBounds == RowBounds.DEFAULT) { return invocation.proceed(); } BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql"); String originalSql = boundSql.getSql(); Connection connection = (Connection) invocation.getArgs()[0]; if (isDynamicDataSource()) { dialectType = JdbcUtils.getDbType(connection.getMetaData().getURL()).getDb(); } if (rowBounds instanceof Pagination) { Pagination page = (Pagination) rowBounds; boolean orderBy = true; if (page.isSearchCount()) { CountOptimize countOptimize = SqlUtils.getCountOptimize(originalSql, optimizeType, dialectType, page.isOptimizeCount()); orderBy = countOptimize.isOrderBy(); this.queryTotal(countOptimize.getCountSQL(), mappedStatement, boundSql, page, connection); if (page.getTotal() <= 0) { return invocation.proceed(); } } String buildSql = SqlUtils.concatOrderBy(originalSql, page, orderBy); originalSql = DialectFactory.buildPaginationSql(page, buildSql, dialectType, dialectClazz); } else { // support physical Pagination for RowBounds originalSql = DialectFactory.buildPaginationSql(rowBounds, originalSql, dialectType, dialectClazz); } /* * <p> ? </p> <p> ???????</p> */ metaStatementHandler.setValue("delegate.boundSql.sql", originalSql); metaStatementHandler.setValue("delegate.rowBounds.offset", RowBounds.NO_ROW_OFFSET); metaStatementHandler.setValue("delegate.rowBounds.limit", RowBounds.NO_ROW_LIMIT); return invocation.proceed(); } /** * ? * * @param sql * @param mappedStatement * @param boundSql * @param page */ protected void queryTotal(String sql, MappedStatement mappedStatement, BoundSql boundSql, Pagination page, Connection connection) { try (PreparedStatement statement = connection.prepareStatement(sql)) { DefaultParameterHandler parameterHandler = new MybatisDefaultParameterHandler(mappedStatement, boundSql.getParameterObject(), boundSql); parameterHandler.setParameters(statement); int total = 0; try (ResultSet resultSet = statement.executeQuery()) { if (resultSet.next()) { total = resultSet.getInt(1); } } page.setTotal(total); /* * */ int pages = page.getPages(); if (overflowCurrent && (page.getCurrent() > pages)) { page = new Pagination(1, page.getSize()); page.setTotal(total); } } catch (Exception e) { logger.error("Error: Method queryTotal execution error !", e); } } public Object plugin(Object target) { if (target instanceof StatementHandler) { return Plugin.wrap(target, this); } return target; } public void setProperties(Properties prop) { String dialectType = prop.getProperty("dialectType"); String dialectClazz = prop.getProperty("dialectClazz"); if (StringUtils.isNotEmpty(dialectType)) { this.dialectType = dialectType; } if (StringUtils.isNotEmpty(dialectClazz)) { this.dialectClazz = dialectClazz; } } public void setDialectType(String dialectType) { this.dialectType = dialectType; } public void setDialectClazz(String dialectClazz) { this.dialectClazz = dialectClazz; } public void setOverflowCurrent(boolean overflowCurrent) { this.overflowCurrent = overflowCurrent; } public void setOptimizeType(String optimizeType) { this.optimizeType = optimizeType; } public boolean isDynamicDataSource() { return dynamicDataSource; } public void setDynamicDataSource(boolean dynamicDataSource) { this.dynamicDataSource = dynamicDataSource; } }