MYSQL-SHOW STATUS

Caused by: com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"

mysql> show status like 'Threads_connected';

+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| Threads_connected | 4     |
+-------------------+-------+
1 row in set (0.00 sec)

http://dev.mysql.com/doc/refman/4.1/ja/show-status.html