【原创】为MybatisPlus增加一个逻辑删除插件，让XML中的SQL也能自动增加逻辑删除功能

前言

看到这个标题有人就要说了，D哥啊，MybatisPlus不是本来就有逻辑删除的配置吗，比如@TableLogic注解，配置文件里也能添加如下配置设置逻辑删除。

mybatis-plus:mapper-locations: classpath*:mapper/*.xmlconfiguration:mapUnderscoreToCamelCase: trueglobal-config:db-config:logic-delete-field: dellogic-delete-value: 1logic-notDelete-value: 0

但是我想说，xml中添加了逻辑删除了吗？很明显这个没有，MybatisPlus只在QueryWrapper中做了手脚，而xml是Mybatis的功能，非MybatisPlus的功能。而xml中写SQL又是我工作中最常用到的，优势在于SQL可读性强，结合MybatisX插件并在IDEA中连接database后能够直接跳转到方法和表，且对多表join和子查询支持都比QueryWrapper来得好。而逻辑删除又是会经常漏掉的字段，虽然说手动添加也不费多少时间，但是麻烦的是容易漏掉，特别是子查询和join的情况，而且时间积少成多，我觉得有必要解决这个问题。

本插件适用于绝大部分表都拥有逻辑删除字段的情况！！

本文使用的MybatisPlus的版本为3.5.3.1

不多说了，直接上代码！


/*** @author DCT* @version 1.0* @date 2023/11/9 23:10:18* @description*/
@Slf4j
public class DeleteMpInterceptor implements InnerInterceptor {public static final String LOGIC_DELETE = "LOGIC_DELETE";public static final List<String> excludeFunctions = new ArrayList<>();protected String deleteFieldName;public DeleteMpInterceptor(String deleteFieldName) {this.deleteFieldName = deleteFieldName;}static {excludeFunctions.add("selectList");excludeFunctions.add("selectById");excludeFunctions.add("selectBatchIds");excludeFunctions.add("selectByMap");excludeFunctions.add("selectOne");excludeFunctions.add("selectCount");excludeFunctions.add("selectObjs");excludeFunctions.add("selectPage");excludeFunctions.add("selectMapsPage");}@SneakyThrows@Overridepublic void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {if (InterceptorIgnoreHelper.willIgnoreOthersByKey(ms.getId(), LOGIC_DELETE)) {return;}if (StringUtils.isBlank(deleteFieldName)) {// INFO: Zhouwx: 2023/11/20 没有设置逻辑删除的字段名，也忽略添加逻辑删除return;}PluginUtils.MPBoundSql mpBs = PluginUtils.mpBoundSql(boundSql);String sql = mpBs.sql();Statement statement = CCJSqlParserUtil.parse(sql);if (!(statement instanceof Select)) {return;}String id = ms.getId();int lastIndexOf = id.lastIndexOf(".");String functionName = id.substring(lastIndexOf + 1);if (excludeFunctions.contains(functionName)) {// INFO: DCT: 2023/11/12 QueryWrapper的查询，本来就会加逻辑删除，不需要再加了return;}Select select = (Select) statement;SelectBody selectBody = select.getSelectBody();// INFO: DCT: 2023/11/12 处理核心业务handleSelectBody(selectBody);// INFO: DCT: 2023/11/12 将处理完的数据重新转为MPBoundSqlString sqlChange = statement.toString();mpBs.sql(sqlChange);}protected void handleSelectBody(SelectBody selectBody) {if (selectBody instanceof PlainSelect) {PlainSelect plainSelect = (PlainSelect) selectBody;// INFO: DCT: 2023/11/12 处理join中的内容handleJoins(plainSelect);Expression where = plainSelect.getWhere();FromItem fromItem = plainSelect.getFromItem();EqualsTo equalsTo = getEqualTo(fromItem);if (where == null) {// INFO: DCT: 2023/11/12 where条件为空，增加一个where，且赋值为 表名.del = 0plainSelect.setWhere(equalsTo);} else {// INFO: DCT: 2023/11/12 普通where，后面直接加上本表的 表名.del = 0 AndExpression andExpression = new AndExpression(where, equalsTo);plainSelect.setWhere(andExpression);// INFO: DCT: 2023/11/12 有子查询的处理子查询 handleWhereSubSelect(where);}}}/*** 这一段来自MybatisPlus的租户插件源码，通过递归的方式加上需要的SQL** @param where*/protected void handleWhereSubSelect(Expression where) {if (where == null) {return;}if (where instanceof FromItem) {processOtherFromItem((FromItem) where);return;}if (where.toString().indexOf("SELECT") > 0) {// 有子查询if (where instanceof BinaryExpression) {// 比较符号 , and , or , 等等BinaryExpression expression = (BinaryExpression) where;handleWhereSubSelect(expression.getLeftExpression());handleWhereSubSelect(expression.getRightExpression());} else if (where instanceof InExpression) {// inInExpression expression = (InExpression) where;Expression inExpression = expression.getRightExpression();if (inExpression instanceof SubSelect) {handleSelectBody(((SubSelect) inExpression).getSelectBody());}} else if (where instanceof ExistsExpression) {// existsExistsExpression expression = (ExistsExpression) where;handleWhereSubSelect(expression.getRightExpression());} else if (where instanceof NotExpression) {// not existsNotExpression expression = (NotExpression) where;handleWhereSubSelect(expression.getExpression());} else if (where instanceof Parenthesis) {Parenthesis expression = (Parenthesis) where;handleWhereSubSelect(expression.getExpression());}}}/*** 处理子查询等*/protected void processOtherFromItem(FromItem fromItem) {// 去除括号while (fromItem instanceof ParenthesisFromItem) {fromItem = ((ParenthesisFromItem) fromItem).getFromItem();}if (fromItem instanceof SubSelect) {SubSelect subSelect = (SubSelect) fromItem;if (subSelect.getSelectBody() != null) {// INFO: Zhouwx: 2023/11/20 递归从select开始查找handleSelectBody(subSelect.getSelectBody());}} else if (fromItem instanceof ValuesList) {log.debug("Perform a subQuery, if you do not give us feedback");} else if (fromItem instanceof LateralSubSelect) {LateralSubSelect lateralSubSelect = (LateralSubSelect) fromItem;if (lateralSubSelect.getSubSelect() != null) {SubSelect subSelect = lateralSubSelect.getSubSelect();if (subSelect.getSelectBody() != null) {// INFO: Zhouwx: 2023/11/20 递归从select开始查找handleSelectBody(subSelect.getSelectBody());}}}}protected void handleJoins(PlainSelect plainSelect) {List<Join> joins = plainSelect.getJoins();if (joins == null) {return;}for (Join join : joins) {// INFO: DCT: 2023/11/12 获取表别名，并获取 表.del = 0FromItem rightItem = join.getRightItem();EqualsTo equalsTo = getEqualTo(rightItem);// INFO: DCT: 2023/11/12 获取on右边的表达式Expression onExpression = join.getOnExpression();// INFO: DCT: 2023/11/12 给表达式增加 and 表.del = 0AndExpression andExpression = new AndExpression(onExpression, equalsTo);ArrayList<Expression> expressions = new ArrayList<>();expressions.add(andExpression);// INFO: DCT: 2023/11/12 目前的这个表达式就是and后的表达式了，不用再增加原来的表达式，因为这个and表达式已经包含了原表达式所有的内容了join.setOnExpressions(expressions);}}protected EqualsTo getEqualTo(FromItem fromItem) {Alias alias = fromItem.getAlias();String aliasName = "";if (alias == null) {if (fromItem instanceof Table) {Table table = (Table) fromItem;aliasName = table.getName();}} else {aliasName = alias.getName();}EqualsTo equalsTo = new EqualsTo();Column leftColumn = new Column();leftColumn.setColumnName(aliasName + "." + deleteFieldName);equalsTo.setLeftExpression(leftColumn);equalsTo.setRightExpression(new LongValue(0));return equalsTo;}
}

代码说明

这代码中已经有很多注释了，其实整段代码并非100%我的原创，而是借鉴了MybatisPlus自己的TenantLineInnerIntercept，因为两者的功能实际上非常详尽，我依葫芦画瓢造了一个，特别是中间的handleWhereSubSelect方法，令人拍案叫绝！使用大量递归，通过非常精简的代码处理完了SQL查询中所有的子查询。

getEqualTo方法可以算是逻辑删除插件的核心代码了，先判断表是否存在别名，如果有，就拿别名，如果没有就拿表名，防止出现多个表都有逻辑删除字段的情况下指代不清的情况，出现查询ambiguous错误。通过net.sf.jsqlparser中的EqualsTo表达式，拼上字段名和未被逻辑删除的值0（这里可以按照自己的情况进行修改！）

顶上的excludeFunctions是为了排除QueryWrapper的影响，因为QueryWrapper自己会加上逻辑删除，而这个插件还会再添加一个逻辑删除，导致出现重复，打印出来的SQL不美观。

使用方法

和MybatisPlus其他的插件一样，都通过@Bean的方式进行配置

    @Value("${mybatis-plus.global-config.db-config.logic-delete-field}")private String deleteFieldName;@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();interceptor.addInnerInterceptor(new DeleteMpInterceptor(deleteFieldName));return interceptor;}

我这里的deleteFieldName直接借用了MybatisPlus自己的逻辑删除配置，可以自己设置

排除使用这个插件

如果有几张表是没有逻辑删除字段的，那么这个插件自动补的逻辑删除字段则会导致SQL出现报错，可以通过添加以下注解@InterceptorIgnore排除插件对于该方法的生效

@Repository
interface ExampleMapper : BaseMapper<ExampleEntity> {@InterceptorIgnore(others = [DeleteMpInterceptor.LOGIC_DELETE + "@true"])fun findByList(query: ExampleQo): List<ExampleListVo>
}

上面的代码是Kotlin写的，但是不妨碍查看

运行效果

mapper中代码为：

/*** @author DCTANT* @version 1.0* @date 2023/11/20 17:40:41* @description*/
@Repository
interface ExampleMapper : BaseMapper<ExampleEntity> {fun findByList(query: ExampleQo): List<ExampleListVo>
}

xml中的代码为：

    <select id="findByList" resultType="com.itdct.server.admin.example.vo.ExampleListVo">select t.* from test_example as t<where><if test="name != null and name != ''">and t.name = #{name}</if><if test="number != null">and t.number = #{number}</if><if test="keyword != null and keyword != ''">and t.name like concat('%',#{keyword},'%')</if><if test="startTime != null">and t.create_time &gt; #{startTime}</if><if test="endTime != null">and t.create_time &lt; #{endTime}</if></where>order by t.create_time desc</select>

执行效果为：