前言
本文主要是讲通过 MyBaits 的 Interceptor 的拓展点进行对 MyBatis 执行 SQL 之前做一个逻辑拦截实现自定义逻辑的插入执行。
适合场景：1. 比如限制数据库查询最大访问条数；2. 限制登录用户只能访问当前机构数据。
定义是否开启注解
定义是否开启注解, 主要做的一件事情就是是否添加 SQL 拦截器。
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// 全局开启@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.TYPE)@Documented@Import(MyBatisSqlInterceptorConfiguration.class)public @interface EnableSqlInterceptor {}// 自定义注解@Target({ElementType.METHOD })@Retention(RetentionPolicy.RUNTIME)public @interface DataScope {} |
注册SQL 拦截器
注册一个 SQL 拦截器，会对符合条件的 SQL 查询操作进行拦截。
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public class MyBatisSqlInterceptorConfiguration implements ApplicationContextAware { @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { SqlSessionFactory sqlSessionFactory = applicationContext.getBean(SqlSessionFactory.class); sqlSessionFactory.getConfiguration().addInterceptor(new MyBatisInterceptor()); }} |
处理逻辑
在处理逻辑中，我主要是做一个简单的 limit 1 案例，如果是自己需要做其他的逻辑需要修改
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@Slf4j@Intercepts( { @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}), @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}), })public class MyBatisInterceptor implements Interceptor { private static final Logger LOGGER = LoggerFactory.getLogger(MyBatisInterceptor.class); @Override public Object intercept(Invocation invocation) throws Throwable { // TODO Auto-generated method stub Object[] args = invocation.getArgs(); MappedStatement ms = (MappedStatement) args[0]; Object parameter = args[1]; RowBounds rowBounds = (RowBounds) args[2]; ResultHandler resultHandler = (ResultHandler) args[3]; Executor executor = (Executor) invocation.getTarget(); CacheKey cacheKey; BoundSql boundSql; //由于逻辑关系，只会进入一次 if (args.length == 4) { //4 个参数时 boundSql = ms.getBoundSql(parameter); cacheKey = executor.createCacheKey(ms, parameter, rowBounds, boundSql); } else { //6 个参数时 cacheKey = (CacheKey) args[4]; boundSql = (BoundSql) args[5]; } DataScope dataScope = getDataScope(ms); if (Objects.nonNull(dataScope)) { String origSql = boundSql.getSql(); log.info("origSql : {}", origSql); // 组装新的 sql // todo you weaving business String newSql = origSql + " limit 1"; // 重新new一个查询语句对象 BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), newSql, boundSql.getParameterMappings(), boundSql.getParameterObject()); // 把新的查询放到statement里 MappedStatement newMs = newMappedStatement(ms, new BoundSqlSource(newBoundSql)); for (ParameterMapping mapping : boundSql.getParameterMappings()) { String prop = mapping.getProperty(); if (boundSql.hasAdditionalParameter(prop)) { newBoundSql.setAdditionalParameter(prop, boundSql.getAdditionalParameter(prop)); } } args[0] = newMs; if (args.length == 6) { args[5] = newMs.getBoundSql(parameter); } } LOGGER.info("mybatis intercept sql:{},Mapper方法是：{}", boundSql.getSql(), ms.getId()); return invocation.proceed(); } private MappedStatement newMappedStatement(MappedStatement ms, SqlSource newSqlSource) { MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType()); builder.resource(ms.getResource()); builder.fetchSize(ms.getFetchSize()); builder.statementType(ms.getStatementType()); builder.keyGenerator(ms.getKeyGenerator()); if (ms.getKeyProperties() != null && ms.getKeyProperties().length > 0) { builder.keyProperty(ms.getKeyProperties()[0]); } builder.timeout(ms.getTimeout()); builder.parameterMap(ms.getParameterMap()); builder.resultMaps(ms.getResultMaps()); builder.resultSetType(ms.getResultSetType()); builder.cache(ms.getCache()); builder.flushCacheRequired(ms.isFlushCacheRequired()); builder.useCache(ms.isUseCache()); return builder.build(); } private DataScope getDataScope(MappedStatement mappedStatement) { String id = mappedStatement.getId(); // 获取 Class Method String clazzName = id.substring(0, id.lastIndexOf('.')); String mapperMethod = id.substring(id.lastIndexOf('.') + 1); Class<?> clazz; try { clazz = Class.forName(clazzName); } catch (ClassNotFoundException e) { return null; } Method[] methods = clazz.getMethods(); DataScope dataScope = null; for (Method method : methods) { if (method.getName().equals(mapperMethod)) { dataScope = method.getAnnotation(DataScope.class); break; } } return dataScope; } @Override public Object plugin(Object target) { // TODO Auto-generated method stub LOGGER.info("MysqlInterCeptor plugin>>>>>>>{}", target); return Plugin.wrap(target, this); } @Override public void setProperties(Properties properties) { // TODO Auto-generated method stub String dialect = properties.getProperty("dialect"); LOGGER.info("mybatis intercept dialect:>>>>>>>{}", dialect); } /** * 定义一个内部辅助类，作用是包装 SQL */ class BoundSqlSource implements SqlSource { private BoundSql boundSql; public BoundSqlSource(BoundSql boundSql) { this.boundSql = boundSql; } public BoundSql getBoundSql(Object parameterObject) { return boundSql; } }} |
如何使用
我们在 XXXMapper 中对应的数据操作方法只要加入 @DataScope 注解即可。
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@Mapperpublic interface OrderMapper { @Select("select 1 ") @DataScope Intger selectOne();} |
参考资料
总结
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原文链接：https://juejin.cn/post/7021508758777888799
