Apache Calcite进行SQL解析(java代码实例)

Calcite是一款开源SQL解析工具, 可以将各种SQL语句解析成抽象语法树AST(Abstract Syntax Tree), 之后通过操作AST就可以把SQL中所要表达的算法与关系体现在具体代码之中，今天通过代码实例给大家介绍Apache Calcite进行SQL解析问题，感兴趣的朋友一起看看吧

背景

当一个项目分了很多模块，很多个服务的时候，一些公共的配置就需要统一管理了，于是就有了元数据驱动！

简介

什么是Calcite？
是一款开源SQL解析工具, 可以将各种SQL语句解析成抽象语法树AST(Abstract Syntax Tree), 之后通过操作AST就可以把SQL中所要表达的算法与关系体现在具体代码之中。
Calcite能做啥？

SQL 解析
SQL 校验
查询优化
SQL 生成器
数据连接

实例

今天主要是贴出一个java代码实例，实现了：解析SQL语句中的表名
上代码：
SQL语句转化：

public static SqlNode parseStatement(String sql) { SqlParser parser = SqlParser.create(sql, config.getParserConfig()); try { return parser.parseQuery(); } catch (Exception e) { e.printStackTrace(); throw new UnsupportedOperationException("operation not allowed"); } }

解析Select中的表名：

private static Set extractSourceTableInSelectSql(SqlNode sqlNode, boolean fromOrJoin) { if (sqlNode == null) { return new HashSet<>(); } final SqlKind sqlKind = sqlNode.getKind(); if (SqlKind.SELECT.equals(sqlKind)) { SqlSelect selectNode = (SqlSelect) sqlNode; Set selectList = new HashSet<>(extractSourceTableInSelectSql(selectNode.getFrom(), true)); selectNode.getSelectList().getList().stream().filter(node -> node instanceof SqlCall) .forEach(node -> selectList.addAll(extractSourceTableInSelectSql(node, false))); selectList.addAll(extractSourceTableInSelectSql(selectNode.getWhere(), false)); selectList.addAll(extractSourceTableInSelectSql(selectNode.getHaving(), false)); return selectList; if (SqlKind.JOIN.equals(sqlKind)) { SqlJoin sqlJoin = (SqlJoin) sqlNode; Set joinList = new HashSet<>(); joinList.addAll(extractSourceTableInSelectSql(sqlJoin.getLeft(), true)); joinList.addAll(extractSourceTableInSelectSql(sqlJoin.getRight(), true)); return joinList; if (SqlKind.AS.equals(sqlKind)) { SqlCall sqlCall = (SqlCall) sqlNode; return extractSourceTableInSelectSql(sqlCall.getOperandList().get(0), fromOrJoin); if (SqlKind.IDENTIFIER.equals(sqlKind)) { Set identifierList = new HashSet<>(); if (fromOrJoin) { SqlIdentifier sqlIdentifier = (SqlIdentifier) sqlNode; identifierList.add(sqlIdentifier.toString()); } return identifierList; Set defaultList = new HashSet<>(); if (sqlNode instanceof SqlCall) { SqlCall call = (SqlCall) sqlNode; call.getOperandList() .forEach(node -> defaultList.addAll(extractSourceTableInSelectSql(node, false))); return defaultList; }

解析Insert语句中的表名：

private static Set extractSourceTableInInsertSql(SqlNode sqlNode, boolean fromOrJoin) { SqlInsert sqlInsert = (SqlInsert) sqlNode; Set insertList = new HashSet<>(extractSourceTableInSelectSql(sqlInsert.getSource(), false)); final SqlNode targetTable = sqlInsert.getTargetTable(); if (targetTable instanceof SqlIdentifier) { insertList.add(((SqlIdentifier) targetTable).toString()); } return insertList; }

执行效果

private static final String sql0 = "SELECT MIN(relation_id) FROM tableA JOIN TableB  GROUP BY account_instance_id, follow_account_instance_id HAVING COUNT(*)>1"; private static final String sql1 = "SELECT * FROM blog_user_relation a WHERE (a.account_instance_id,a.follow_account_instance_id) IN (SELECT account_instance_id,follow_account_instance_id FROM Blogs_info GROUP BY account_instance_id, follow_account_instance_id HAVING COUNT(*) > 1)"; private static final String sql2 = "select name from (select * from student)"; private static final String sql3 = "SELECT * FROM Student LEFT JOIN Grade ON Student.sID = Grade.gID\n" + "UNION\n" + "SELECT * FROM Student RIGHT JOIN Grade ON Student.sID = Grade.gID"; private static final String sql4 = "SELECT *\n" + "FROM teacher\n" + "WHERE birth = (SELECT MIN(birth)\n" + "               FROM employee)"; private static final String sql5 = "SELECT sName\n" + "FROM Student\n" + "WHERE '450' NOT IN (SELECT courseID\n" + "                    FROM Course\n" + "                    WHERE sID = Student.sID)"; final SqlNode sqlNode0 = parseStatement(sql0); System.out.println("sqlNode0: " + extractSourceTableInSelectSql(sqlNode0, false));

结果为：