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一、前言

MyBatis-Plus原本是提供了逻辑删除的功能。

但如果在xml中直接写sql，它的逻辑删除是未生效的。
网上看了下，未找到这一解决方案…
下面我们来自定义一个简单的逻辑删除插件来实现这一功能^_^

二、自定义逻辑删除插件

1、编写插件LogicDeleteInterceptor

@Slf4j
@AllArgsConstructor
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})})
public class LogicDeleteInterceptor implements Interceptor {@Overridepublic Object intercept(Invocation invocation) throws Throwable {StatementHandler statementHandler = PluginUtils.realTarget(invocation.getTarget());MetaObject metaObject = SystemMetaObject.forObject(statementHandler);// 判断是不是SELECT操作 不是直接过滤MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");if (!SqlCommandType.SELECT.equals(mappedStatement.getSqlCommandType())) {return invocation.proceed();}BoundSql boundSql = (BoundSql) metaObject.getValue("delegate.boundSql");// 执行的SQL语句String originalSql = boundSql.getSql();// SQL语句的参数Object parameterObject = boundSql.getParameterObject();String finalSql = this.handleSql(originalSql);
//        System.err.println("逻辑删除处理过后的SQL: \n" + finalSql);metaObject.setValue("delegate.boundSql.sql", finalSql);return invocation.proceed();}/*** 改写SQL* {@link com.baomidou.mybatisplus.extension.plugins.inner.DataPermissionInterceptor}** @param originalSql 执行的SQL语句* @return 处理后的SQL* @author zhengqingya* @date 2022/1/13 10:43*/private String handleSql(String originalSql) throws JSQLParserException {CCJSqlParserManager parserManager = new CCJSqlParserManager();Select select = (Select) parserManager.parse(new StringReader(originalSql));SelectBody selectBody = select.getSelectBody();if (selectBody instanceof PlainSelect) {this.setWhere((PlainSelect) selectBody);} else if (selectBody instanceof SetOperationList) {SetOperationList setOperationList = (SetOperationList) selectBody;List<SelectBody> selectBodyList = setOperationList.getSelects();selectBodyList.forEach(s -> this.setWhere((PlainSelect) s));}return select.toString();}/*** 设置 where 条件  --  使用CCJSqlParser将原SQL进行解析并改写* @param plainSelect 查询对象*/@SneakyThrows(Exception.class)protected void setWhere(PlainSelect plainSelect) {Table fromItem = (Table) plainSelect.getFromItem();// 有别名用别名，无别名用表名，防止字段冲突报错Alias fromItemAlias = fromItem.getAlias();String originalTableName = fromItem.getName();String mainTableName = fromItemAlias == null ? originalTableName : fromItemAlias.getName();// 判断是否需要逻辑删除,如果不需要直接过滤if (!MybatisPlusConfig.LOGIC_DELETE_TABLE.contains(originalTableName)) {return;}// 构建子查询 -- 逻辑删除String dataSql = mainTableName + ".is_deleted = 0";if (plainSelect.getWhere() == null) {plainSelect.setWhere(CCJSqlParserUtil.parseCondExpression(dataSql));} else {plainSelect.setWhere(new AndExpression(plainSelect.getWhere(), CCJSqlParserUtil.parseCondExpression(dataSql)));}}/*** 生成拦截对象的代理* @param target 目标对象* @return 代理对象*/@Overridepublic Object plugin(Object target) {if (target instanceof StatementHandler) {return Plugin.wrap(target, this);}return target;}/*** mybatis配置的属性* @param properties mybatis配置的属性*/@Overridepublic void setProperties(Properties properties) {}}

2、配置需要逻辑删除的表

public static Set<String> LOGIC_DELETE_TABLE = new HashSet<>();static {LOGIC_DELETE_TABLE.add("t_demo");
}

3、启用插件

@Bean
@ConditionalOnMissingBean
public LogicDeleteInterceptor logicDeleteInterceptor() {return new LogicDeleteInterceptor();
}

4、测试

可以看见已经自动加上了is_deleted = 0

三、本文案例demo源码

https://gitee.com/zhengqingya/small-tools

今日分享语句：
坚定自己想要的。