MyBatis-Plus工具使用之EntityWrapper解析 MyBatis-Plus工具使用之EntityWrap

EntityWrapper使用解析
EntityWrapper源码解读

EntityWrapper使用解析 1、项目中引入jar包，我这里使用Maven构建

com.baomidoumybatis-plus仓库最高版本号snapshotshttps://oss.sonatype.org/content/repositories/snapshots/

特别说明： Mybatis及Mybatis-Spring依赖请勿加入项目配置，以免引起版本冲突！！！Mybatis-Plus会自动帮你维护！
2、springboot项目中application.yml文件中加上

mybatisplus:enabled: truegeneric:enabled: truedialectType: mysql

传统SSM项目，修改配置文件，将mybatis的sqlSessionFactory替换成mybatis-plus的即可,mybatis-plus只做了一些功能的扩展:

3、创建Mapper、xml,创建Mapper时继承BaseMapper，xml正常（省略xml信息）

public interface UserMapper extends BaseMapper {}

4、实现类继承ServiceImpl

@Service@Slf4jpublic class UserServiceImpl extends ServiceImpl implements IUserService {public void queryUserList(UserDto dto){EntityWrapper ew = new EntityWrapper(); ew.where("deleted={0}", 1); ew.in("user_type", "1"); ew.eq("role", "1"); ew.eq("status", "1"); ew.orderBy("id"); ew.orderBy("created_time", true); log.info("selectList condition:{}", ew.getSqlSegment()); List userList = this.selectList(ew); }}

更多资料，请查看： mybaits-plus官方文档

EntityWrapper源码解读 mybatis plus内置了好多CRUD，其中 EntityWrapper这个类就是。
这个类是mybatis plus帮我们写好的好多接口，就如同我们在dao层写好方法在xml中实现一样。
那么这个友好的类给我们实现了哪些方法呐，今天我们来通过看看源码，来具体说说

/** * Copyright (c) 2011-2014, hubin (jobob@qq.com). * * 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.mapper; import java.io.Serializable; import java.util.Arrays; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.concurrent.atomic.AtomicInteger; import com.baomidou.mybatisplus.enums.SqlLike; import com.baomidou.mybatisplus.exceptions.MybatisPlusException; import com.baomidou.mybatisplus.toolkit.ArrayUtils; import com.baomidou.mybatisplus.toolkit.CollectionUtils; import com.baomidou.mybatisplus.toolkit.MapUtils; import com.baomidou.mybatisplus.toolkit.SqlUtils; import com.baomidou.mybatisplus.toolkit.StringUtils; /** * * 条件构造抽象类，定义T-SQL语法 *
* * @author hubin , yanghu , Dyang , Caratacus * @Date 2016-11-7 */@SuppressWarnings("serial")public abstract class Wrapper implements Serializable { /*** 占位符*/private static final String PLACE_HOLDER = "{%s}"; private static final String MYBATIS_PLUS_TOKEN = "#{%s.paramNameValuePairs.%s}"; private static final String MP_GENERAL_PARAMNAME = "MPGENVAL"; private static final String DEFAULT_PARAM_ALIAS = "ew"; protected String paramAlias = null; /*** SQL 查询字段内容，例如：id,name,age*/protected String sqlSelect = null; /*** 实现了TSQL语法的SQL实体*/protected SqlPlus sql = new SqlPlus(); /*** 自定义是否输出sql为 WHERE OR AND OR OR*/protected Boolean isWhere; /*** 拼接WHERE后应该是AND还是OR*/protected String AND_OR = "AND"; private Map paramNameValuePairs = new HashMap<>(4); private AtomicInteger paramNameSeq = new AtomicInteger(0); /*** 兼容EntityWrapper** @return*/public T getEntity() {return null; } public String getSqlSelect() {if (StringUtils.isEmpty(sqlSelect)) {return null; }return stripSqlInjection(sqlSelect); } public Wrapper setSqlSelect(String sqlSelect) {if (StringUtils.isNotEmpty(sqlSelect)) {this.sqlSelect = sqlSelect; }return this; } /*** SQL 片段 (子类实现)*/public abstract String getSqlSegment(); public String toString() {String sqlSegment = getSqlSegment(); if (StringUtils.isNotEmpty(sqlSegment)) {sqlSegment = sqlSegment.replaceAll("#\\{" + getParamAlias() + ".paramNameValuePairs.MPGENVAL[0-9]+}", "\\?"); }return sqlSegment; } /*** * SQL中WHERE关键字跟的条件语句*
* * eg: ew.where("name='zhangsan'").where("id={0}","123"); * * 输出: WHERE (NAME='zhangsan' AND id=123)*
** @param sqlWhere where语句* @param params参数集* @return this*/public Wrapper where(String sqlWhere, Object... params) {sql.WHERE(formatSql(sqlWhere, params)); return this; } /*** * 等同于SQL的"field=value"表达式*
** @param column* @param params* @return*/public Wrapper eq(String column, Object params) {sql.WHERE(formatSql(String.format("%s = {0}", column), params)); return this; } /*** * 等同于SQL的"field <> value"表达式*
** @param column* @param params* @return*/public Wrapper ne(String column, Object params) {sql.WHERE(formatSql(String.format("%s <> {0}", column), params)); return this; } /*** * 等同于SQL的"field=value"表达式*
** @param params* @return*/@SuppressWarnings({"rawtypes", "unchecked"})public Wrapper allEq(Map params) {if (MapUtils.isNotEmpty(params)) {Iterator iterator = params.entrySet().iterator(); while (iterator.hasNext()) {Map.Entry entry = (Map.Entry) iterator.next(); Object value = https://www.it610.com/article/entry.getValue(); if (StringUtils.checkValNotNull(value)) {sql.WHERE(formatSql(String.format("%s = {0}", entry.getKey()), entry.getValue())); } } }return this; } /*** * 等同于SQL的"field>value"表达式*
** @param column* @param params* @return*/public Wrapper gt(String column, Object params) {sql.WHERE(formatSql(String.format("%s > {0}", column), params)); return this; } /*** * 等同于SQL的"field>=value"表达式*
** @param column* @param params* @return*/public Wrapper ge(String column, Object params) {sql.WHERE(formatSql(String.format("%s >= {0}", column), params)); return this; } /*** * 等同于SQL的"field ** @param column* @param params* @return*/public Wrapper lt(String column, Object params) {sql.WHERE(formatSql(String.format("%s < {0}", column), params)); return this; } /*** * 等同于SQL的"field<=value"表达式*
** @param column* @param params* @return*/public Wrapper le(String column, Object params) {sql.WHERE(formatSql(String.format("%s <= {0}", column), params)); return this; } /*** * AND 连接后续条件*
** @param sqlAnd and条件语句* @param params 参数集* @return this*/public Wrapper and(String sqlAnd, Object... params) {sql.AND().WHERE(formatSql(sqlAnd, params)); return this; } /*** * 使用AND连接并换行*
* * eg: ew.where("name='zhangsan'").and("id=11").andNew("statu=1"); 输出： WHERE* (name='zhangsan' AND id=11) AND (statu=1)*
** @param sqlAnd AND 条件语句* @param params 参数值* @return this*/public Wrapper andNew(String sqlAnd, Object... params) {sql.AND_NEW().WHERE(formatSql(sqlAnd, params)); return this; } /*** * 使用AND连接并换行*
* ** @return this*/public Wrapper and() {sql.AND_NEW(); return this; } /*** * 使用OR连接并换行*
** @return this*/public Wrapper or() {sql.OR_NEW(); return this; } /*** * 添加OR条件*
** @param sqlOror 条件语句* @param params 参数集* @return this*/public Wrapper or(String sqlOr, Object... params) {if (StringUtils.isEmpty(sql.toString())) {AND_OR = "OR"; }sql.OR().WHERE(formatSql(sqlOr, params)); return this; } /*** * 使用OR换行，并添加一个带()的新的条件*
* * eg: ew.where("name='zhangsan'").and("id=11").orNew("statu=1"); 输出： WHERE* (name='zhangsan' AND id=11) OR (statu=1)*
** @param sqlOrAND 条件语句* @param params 参数值* @return this*/public Wrapper orNew(String sqlOr, Object... params) {if (StringUtils.isEmpty(sql.toString())) {AND_OR = "OR"; }sql.OR_NEW().WHERE(formatSql(sqlOr, params)); return this; } /*** 【MyBatis-Plus工具使用之EntityWrapper解析】* SQL中groupBy关键字跟的条件语句*
* * eg: ew.where("name='zhangsan'").groupBy("id,name")*
** @param columns SQL 中的 Group by 语句，无需输入 Group By 关键字* @return this*/public Wrapper groupBy(String columns) {sql.GROUP_BY(columns); return this; } /*** * SQL中having关键字跟的条件语句*
* * eg: ew.groupBy("id,name").having("id={0}",22).and("password is not null")*
** @param sqlHaving having关键字后面跟随的语句* @param params参数集* @return EntityWrapper*/public Wrapper having(String sqlHaving, Object... params) {sql.HAVING(formatSql(sqlHaving, params)); return this; } /*** * SQL中orderby关键字跟的条件语句*
* * eg: ew.groupBy("id,name").having("id={0}",22).and("password is not null"* ).orderBy("id,name")*
** @param columns SQL 中的 order by 语句，无需输入 Order By 关键字* @return this*/public Wrapper orderBy(String columns) {sql.ORDER_BY(columns); return this; } /*** * SQL中orderby关键字跟的条件语句，可根据变更动态排序*
** @param columns SQL 中的 order by 语句，无需输入 Order By 关键字* @param isAsc是否为升序* @return this*/public Wrapper orderBy(String columns, boolean isAsc) {if (StringUtils.isNotEmpty(columns)) {sql.ORDER_BY(columns + (isAsc ? " ASC" : " DESC")); }return this; } /*** LIKE条件语句，value中无需前后%** @param column 字段名称* @param value匹配值* @return this*/public Wrapper like(String column, String value) {handerLike(column, value, SqlLike.DEFAULT, false); return this; } /*** NOT LIKE条件语句，value中无需前后%** @param column 字段名称* @param value匹配值* @return this*/public Wrapper notLike(String column, String value) {handerLike(column, value, SqlLike.DEFAULT, true); return this; } /*** 处理LIKE操作** @param column 字段名称* @param valuelike匹配值* @param isNot是否为NOT LIKE操作*/private void handerLike(String column, String value, SqlLike type, boolean isNot) {if (StringUtils.isNotEmpty(column) && StringUtils.isNotEmpty(value)) {StringBuilder inSql = new StringBuilder(); inSql.append(column); if (isNot) {inSql.append(" NOT"); }inSql.append(" LIKE {0}"); sql.WHERE(formatSql(inSql.toString(), SqlUtils.concatLike(value, type))); }} /*** LIKE条件语句，value中无需前后%** @param column 字段名称* @param value匹配值* @param type* @return this*/public Wrapper like(String column, String value, SqlLike type) {handerLike(column, value, type, false); return this; } /*** NOT LIKE条件语句，value中无需前后%** @param column 字段名称* @param value匹配值* @param type* @return this*/public Wrapper notLike(String column, String value, SqlLike type) {handerLike(column, value, type, true); return this; } /*** is not null 条件** @param columns 字段名称。多个字段以逗号分隔。* @return this*/public Wrapper isNotNull(String columns) {sql.IS_NOT_NULL(columns); return this; } /*** is not null 条件** @param columns 字段名称。多个字段以逗号分隔。* @return this*/public Wrapper isNull(String columns) {sql.IS_NULL(columns); return this; } /*** EXISTS 条件语句，目前适配mysql及oracle** @param value 匹配值* @return this*/public Wrapper exists(String value) {sql.EXISTS(value); return this; } /*** NOT EXISTS条件语句** @param value 匹配值* @return this*/public Wrapper notExists(String value) {sql.NOT_EXISTS(value); return this; } /*** IN 条件语句，目前适配mysql及oracle** @param column 字段名称* @param value逗号拼接的字符串* @return this*/public Wrapper in(String column, String value) {if (StringUtils.isNotEmpty(value)) {in(column, StringUtils.splitWorker(value, ",", -1, false)); }return this; } /*** NOT IN条件语句** @param column 字段名称* @param value逗号拼接的字符串* @return this*/public Wrapper notIn(String column, String value) {if (StringUtils.isNotEmpty(value)) {notIn(column, StringUtils.splitWorker(value, ",", -1, false)); }return this; } /*** IN 条件语句，目前适配mysql及oracle** @param column 字段名称* @param value匹配值 List集合* @return this*/public Wrapper in(String column, Collection value) {if (CollectionUtils.isNotEmpty(value))sql.WHERE(formatSql(inExpression(column, value, false), value.toArray())); return this; } /*** NOT IN 条件语句，目前适配mysql及oracle** @param column 字段名称* @param value匹配值 List集合* @return this*/public Wrapper notIn(String column, Collection value) {if (CollectionUtils.isNotEmpty(value))sql.WHERE(formatSql(inExpression(column, value, true), value.toArray())); return this; } /*** IN 条件语句，目前适配mysql及oracle** @param column 字段名称* @param value匹配值 object数组* @return this*/public Wrapper in(String column, Object[] value) {if (ArrayUtils.isNotEmpty(value))sql.WHERE(formatSql(inExpression(column, Arrays.asList(value), false), value)); return this; } /*** NOT IN 条件语句，目前适配mysql及oracle** @param column 字段名称* @param value匹配值 object数组* @return this*/public Wrapper notIn(String column, Object... value) {if (ArrayUtils.isNotEmpty(value))sql.WHERE(formatSql(inExpression(column, Arrays.asList(value), true), value)); return this; } /*** 获取in表达式** @param column 字段名称* @param value集合List* @param isNot是否为NOT IN操作*/private String inExpression(String column, Collection value, boolean isNot) {if (StringUtils.isNotEmpty(column) && CollectionUtils.isNotEmpty(value)) {StringBuilder inSql = new StringBuilder(); inSql.append(column); if (isNot) {inSql.append(" NOT"); }inSql.append(" IN "); inSql.append("("); int size = value.size(); for (int i = 0; i < size; i++) {inSql.append(String.format(PLACE_HOLDER, i)); if (i + 1 < size) {inSql.append(","); }}inSql.append(")"); return inSql.toString(); }return null; } /*** betwwee 条件语句** @param column 字段名称* @param val1* @param val2* @return this*/public Wrapper between(String column, Object val1, Object val2) {sql.WHERE(formatSql(String.format("%s BETWEEN {0} AND {1}", column), val1, val2)); return this; } /*** NOT betwwee 条件语句** @param column 字段名称* @param val1* @param val2* @return this*/public Wrapper notBetween(String column, Object val1, Object val2) {sql.WHERE(formatSql(String.format("%s NOT BETWEEN {0} AND {1}", column), val1, val2)); return this; } /*** 为了兼容之前的版本,可使用where()或and()替代** @param sqlWhere where sql部分* @param params参数集* @return this*/public Wrapper addFilter(String sqlWhere, Object... params) {return and(sqlWhere, params); } /*** * 根据判断条件来添加条件语句部分使用 andIf() 替代*
* * eg: ew.filterIfNeed(false,"name='zhangsan'").where("name='zhangsan'")* .filterIfNeed(true,"id={0}",22)* * 输出: WHERE (name='zhangsan' AND id=22)*
** @param need是否需要添加该条件* @param sqlWhere 条件语句* @param params参数集* @return this*/public Wrapper addFilterIfNeed(boolean need, String sqlWhere, Object... params) {return need ? where(sqlWhere, params) : this; } /*** * SQL注入内容剥离*
** @param value 待处理内容* @return this*/protected String stripSqlInjection(String value) {return value.replaceAll("('.+--)|(--)|(\\|)|(%7C)", ""); } /*** * 格式化SQL*
** @param sqlStr SQL语句部分* @param params 参数集* @return this*/protected String formatSql(String sqlStr, Object... params) {return formatSqlIfNeed(true, sqlStr, params); } /*** * 根据需要格式化SQL
*
* Format SQL for methods: EntityWrapper.where/and/or...("name={0}", value); * ALL the {i} will be replaced with #{MPGENVALi}
*
* ew.where("sample_name={0}", "haha").and("sample_age > {0}* and sample_age< {1}", 18, 30) TO* sample_name=#{MPGENVAL1} and sample_age> #{MPGENVAL2} and* sample_age< #{MPGENVAL3}
*
** @param need是否需要格式化* @param sqlStr SQL语句部分* @param params 参数集* @return this*/protected String formatSqlIfNeed(boolean need, String sqlStr, Object... params) {if (!need || StringUtils.isEmpty(sqlStr)) {return null; }// #200if (ArrayUtils.isNotEmpty(params)) {for (int i = 0; i < params.length; ++i) {String genParamName = MP_GENERAL_PARAMNAME + paramNameSeq.incrementAndGet(); sqlStr = sqlStr.replace(String.format(PLACE_HOLDER, i),String.format(MYBATIS_PLUS_TOKEN, getParamAlias(), genParamName)); paramNameValuePairs.put(genParamName, params[i]); }}return sqlStr; } /*** * 自定义是否输出sql开头为 `WHERE` OR `AND` OR `OR`*
** @param bool* @return this*/public Wrapper isWhere(Boolean bool) {this.isWhere = bool; return this; } /*** * SQL LIMIT*
** @param begin 起始* @param end结束* @return this*/public Wrapper limit(int begin, int end) {sql.LIMIT(begin, end); return this; } /*** Fix issue 200.** @return* @since 2.0.3*/public Map getParamNameValuePairs() {return paramNameValuePairs; } public String getParamAlias() {return StringUtils.isEmpty(paramAlias) ? DEFAULT_PARAM_ALIAS : paramAlias; } /*** * 调用该方法时应当在吃初始化时优先设置该值不要重复设置该值要不然我就给你抛异常了*
** @param paramAlias* @return*/public Wrapper setParamAlias(String paramAlias) {if (StringUtils.isNotEmpty(getSqlSegment())) {throw new MybatisPlusException("Error: Please call this method when initializing!"); }if (StringUtils.isNotEmpty(this.paramAlias)) {throw new MybatisPlusException("Error: Please do not call the method repeatedly!"); }this.paramAlias = paramAlias; return this; }}