MyBatis自定义SQL拦截器示例详解 MyBatis自定义SQL拦截器示例详解

前言
定义是否开启注解
注册SQL 拦截器
处理逻辑
如何使用
总结

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。

// 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。

public class MyBatisSqlInterceptorConfiguration implements ApplicationContextAware {@Overridepublic 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

@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); @Overridepublic Object intercept(Invocation invocation) throws Throwable {// TODO Auto-generated method stubObject[] 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 businessString 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 = newMappedStatement.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 MethodString 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; }@Overridepublic Object plugin(Object target) {// TODO Auto-generated method stubLOGGER.info("MysqlInterCeptor plugin>>>>>>>{}", target); return Plugin.wrap(target, this); }@Overridepublic void setProperties(Properties properties) {// TODO Auto-generated method stubString 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。

@Mapperpublic interface OrderMapper {@Select("select 1 ")@DataScopeIntger selectOne(); }

参考资料
mybatis.org/mybatis-3/z…

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