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<String> 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<String> 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<String> 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<String> identifierList = new HashSet<>();
if (fromOrJoin) {
SqlIdentifier sqlIdentifier = (SqlIdentifier) sqlNode;
identifierList.add(sqlIdentifier.toString());
}
return identifierList;
Set<String> 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<String> extractSourceTableInInsertSql(SqlNode sqlNode, boolean fromOrJoin) {
SqlInsert sqlInsert = (SqlInsert) sqlNode;
Set<String> 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：
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