tomcat下有文档:Tomcat 4.1\webapps\tomcat-docs\jndi-datasource-examples-howto.html
里面说:Random Connection Closed Exceptions
These can occur when one request gets a db connection from the connection pool and closes it twice. When using a connection pool, closing the connection just returns it to the pool for reuse by another request, it doesn't close the connection. And Tomcat uses multiple threads to handle concurrent requests.