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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@Mapper public interface OrderMapper {
@Select ( "select 1 " ) @DataScope Intger selectOne();
} |
参考资料
mybatis.org/mybatis-3/z …
总结
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原文链接：https://juejin.cn/post/7021508758777888799
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