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引言

某一天，笔者在逛着Github的时候，突然看到seata有个有趣的issue，是一个task。

相关描述：

While running the DruidSQLRecognizerFactoryTest.testIsSqlSyntaxSupports test, a ParserException is thrown when attempting to parse a SQL statement that starts with REPLACE. This indicates that the Druid SQL parser does not support the REPLACE SQL syntax.

简单来说，就是issue主人在做另一个pr的时候，发现DruidSQLRecognizerFactoryTest测试类的方法testIsSqlSyntaxSupports，当解析REPLACE语句的时候，会抛出ParserException。这会导致某个模块的maven构建失败，所以他希望有人可以解决这个问题。

原因🤓

笔者研究了一下，这是因为底层的Druid SQL解析器本来就不支持解析相关的REPLACE语法，而相关测试类的处理方法则是抛出异常并打印相关日志，并没有处理该异常或者转换该异常

异常堆栈：

com.alibaba.druid.sql.parser.ParserException: not supported.pos 7, line 1, column 1, token REPLACEat com.alibaba.druid.sql.parser.SQLStatementParser.parseStatementList(SQLStatementParser.java:616)at com.alibaba.druid.sql.SQLUtils.parseStatements(SQLUtils.java:603)at org.apache.seata.sqlparser.druid.DruidSQLRecognizerFactoryImpl.create(DruidSQLRecognizerFactoryImpl.java:41)at org.apache.seata.sqlparser.druid.DruidSQLRecognizerFactoryTest.testIsSqlSyntaxSupports(DruidSQLRecognizerFactoryTest.java:172)

解决方法😵

在 Seata 中将 Druid 抛出的 ParserException 转换为 Seata 自定义异常

这样做的好处是：

1. 异常处理统一 - 所有不支持的SQL语法都抛出 NotSupportYetException

2. 测试逻辑一致 - 所有数据库类型使用相同的测试断言

3. 兼容性保持 - DruidIsolationTest 等其他测试正常运行

4. 用户体验改善 - 提供统一、友好的错误信息

最终，GitHub Action构建成功 - 不再因为stderr输出而失败

但是，你以为这样就结束了吗？不会！！！

修改一个类往往会有蝴蝶效应。

笔者在修改之后进行maven构建时，发现测试类依然报错，但是明明笔者已经测试过了该类的测试类是否正确运行，那为什么还会有测试类报错呢？答案是因为修改了DruidSQLRecognizerFactoryImpl，而maven构建检查的时候，其他测试类也会一起运行，所以修改的类不能将全部异常都抛出是NotSupportYetException，对只是ParserException才进行转换抛出NotSupportYetException

具体修改：

1.在DruidSQLRecognizerFactoryImpl新建立一个私有方法，用来确定是否是ParserException，如果是，才转换抛出NotSupportYetException，否则按原有异常抛出

2.只对会抛出ParserException的方法进行try-catch，避免用一个大的try-catch来包裹住整个方法，提高可读性

3.将asts等名字转换成sqlStatements，提高可读性

4.使用反射方式检查异常类型，避免直接引用 ParserException（因为ParserException 的直接引用导致类加载时的依赖问题。例如在 DruidIsolationTest 中，类隔离机制会阻止某些Druid类的加载，包括 ParserException）

修改的源码如下：

/*** DruidSQLRecognizerFactoryImpl**/
class DruidSQLRecognizerFactoryImpl implements SQLRecognizerFactory {@Overridepublic List<SQLRecognizer> create(String sql, String dbType) {List<SQLStatement> sqlStatements;try {sqlStatements = SQLUtils.parseStatements(sql, DruidDbTypeAdapter.getAdaptiveDbType(dbType));} catch (RuntimeException e) {if (isParserException(e)) {throw new NotSupportYetException("not support the sql syntax: " + sql + "\nplease see the doc about SQL restrictions https://seata.apache.org/zh-cn/docs/user/sqlreference/dml", e);}throw e;}if (CollectionUtils.isEmpty(sqlStatements)) {throw new UnsupportedOperationException("Unsupported SQL: " + sql);}if (sqlStatements.size() > 1 && !(sqlStatements.stream().allMatch(statement -> statement instanceof SQLUpdateStatement)|| sqlStatements.stream().allMatch(statement -> statement instanceof SQLDeleteStatement))) {throw new UnsupportedOperationException("ONLY SUPPORT SAME TYPE (UPDATE OR DELETE) MULTI SQL -" + sql);}List<SQLRecognizer> recognizers = null;SQLRecognizer recognizer = null;for (SQLStatement sqlStatement : sqlStatements) {SQLOperateRecognizerHolder recognizerHolder =SQLOperateRecognizerHolderFactory.getSQLRecognizerHolder(dbType.toLowerCase());if (sqlStatement instanceof SQLInsertStatement) {recognizer = recognizerHolder.getInsertRecognizer(sql, sqlStatement);} else if (sqlStatement instanceof SQLUpdateStatement) {recognizer = recognizerHolder.getUpdateRecognizer(sql, sqlStatement);} else if (sqlStatement instanceof SQLDeleteStatement) {recognizer = recognizerHolder.getDeleteRecognizer(sql, sqlStatement);} else if (sqlStatement instanceof SQLSelectStatement) {recognizer = recognizerHolder.getSelectForUpdateRecognizer(sql, sqlStatement);}if (sqlStatement instanceof SQLReplaceStatement) {throw new NotSupportYetException("not support the sql syntax with ReplaceStatement:" + sqlStatement +"\nplease see the doc about SQL restrictions https://seata.apache.org/zh-cn/docs/user/sqlreference/dml");}if (recognizer != null && recognizer.isSqlSyntaxSupports()) {if (recognizers == null) {recognizers = new ArrayList<>();}recognizers.add(recognizer);}}return recognizers;}/*** Check if the exception is a Druid ParserException* Use class name comparison to avoid directly referencing the ParserException class*/private boolean isParserException(Throwable e) {if (e == null) {return false;}String className = e.getClass().getName();return "com.alibaba.druid.sql.parser.ParserException".equals(className);}
}

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