mybatis plus 中自定义如下接口，就可以实现流式查询，mybatis 中同样适用。

@Select("select * from t_xxx t ${ew.customSqlSegment}")
@Options(resultSetType = ResultSetType.FORWARD_ONLY, fetchSize = 1000)
@ResultType(ClearReconDiffAbnormalDO.class)
void listByStream(@Param(Constants.WRAPPER) Wrapper<Model> wrapper, ResultHandler<Model> resultHandler);

通用流式查询

编写流式查询的方法：

public class FetchByStream extends AbstractMethod {
          
   
    private static final String METHOD = "fetchByStream";

    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
          
   
        String sqlFormat = "<script>
SELECT %s FROM %s %s %s
</script>";
        String sql = String.format(sqlFormat, sqlSelectColumns(tableInfo, true),
                tableInfo.getTableName(), sqlWhereEntityWrapper(true, tableInfo),
                sqlComment());
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        String statementName = mapperClass.getName() + DOT + METHOD;
        if (configuration.hasStatement(statementName, false)) {
          
   
            logger.warn(LEFT_SQ_BRACKET + statementName + "] Has been loaded by XML or SqlProvider or Mybatiss Annotation, so ignoring this injection for [" + getClass() + RIGHT_SQ_BRACKET);
            return null;
        }
        /* 缓存逻辑处理 */
        return builderAssistant.addMappedStatement(METHOD, sqlSource, StatementType.PREPARED, SqlCommandType.SELECT,
                Integer.MIN_VALUE, null, null, null, null, modelClass,
                ResultSetType.FORWARD_ONLY, true, true, false, null, null, null,
                configuration.getDatabaseId(), languageDriver, null);
    }
}

然后再注入通用方法，在Mapper 写入下方的 method 即可使用。

void fetchByStream(@Param(Constants.WRAPPER) Wrapper<T> wrapper, ResultHandler<T> handler);