如何实现MyBatis自定义SQL拦截器

本篇内容主要讲解"如何实现MyBatis自定义SQL拦截器"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"如何实现MyBatis自定义SQL拦截器"吧!

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 {    @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

@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。

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

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