修复ClassCastException异常，并优化日志。

mybatis-plus-extension/src/main/java/com/baomidou/mybatisplus/extension/plugins/inner/IllegalSQLInnerInterceptor.java

@@ -32,10 +32,7 @@ import net.sf.jsqlparser.expression.operators.relational.NotEqualsTo;
 import net.sf.jsqlparser.schema.Column;
 import net.sf.jsqlparser.schema.Table;
 import net.sf.jsqlparser.statement.delete.Delete;
-import net.sf.jsqlparser.statement.select.Join;
-import net.sf.jsqlparser.statement.select.PlainSelect;
-import net.sf.jsqlparser.statement.select.Select;
-import net.sf.jsqlparser.statement.select.SubSelect;
+import net.sf.jsqlparser.statement.select.*;
 import net.sf.jsqlparser.statement.update.Update;
 import org.apache.ibatis.executor.statement.StatementHandler;
 import org.apache.ibatis.mapping.BoundSql;
@@ -108,13 +105,16 @@ public class IllegalSQLInnerInterceptor extends JsqlParserSupport implements Inn
 
     @Override
     protected void processSelect(Select select, int index, String sql, Object obj) {
-        PlainSelect plainSelect = (PlainSelect) select.getSelectBody();
-        Expression where = plainSelect.getWhere();
-        Assert.notNull(where, "非法SQL，必须要有where条件");
-        Table table = (Table) plainSelect.getFromItem();
-        List<Join> joins = plainSelect.getJoins();
-        validWhere(where, table, (Connection) obj);
-        validJoins(joins, table, (Connection) obj);
+        SelectBody selectBody = select.getSelectBody();
+        if (selectBody instanceof PlainSelect) {
+            PlainSelect plainSelect = (PlainSelect) selectBody;
+            Expression where = plainSelect.getWhere();
+            Assert.notNull(where, "非法SQL，必须要有where条件");
+            Table table = (Table) plainSelect.getFromItem();
+            List<Join> joins = plainSelect.getJoins();
+            validWhere(where, table, (Connection) obj);
+            validJoins(joins, table, (Connection) obj);
+        }
     }
 
     @Override
@@ -329,7 +329,7 @@ public class IllegalSQLInnerInterceptor extends JsqlParserSupport implements Inn
                     indexInfoMap.put(key, indexInfos);
                 }
             } catch (SQLException e) {
-                e.printStackTrace();
+                logger.error(String.format("getIndexInfo fault, with key:{}, dbName:{}, tableName:{}", key, dbName, tableName), e);
             }
         }
         return indexInfos;