JDBCDataProvider and setDataSource() - When to close JDBC objects?

[bfollek]

I'm using JDBCDataProvider and setDataSource() to create a chart in a servlet. I write the chart to the browser using getHtmlData().

 In my testing, it seems that I have to keep the resultset open till after my getHtmlData() call or I get a 500 error. But some of the examples seem to close the connection right after setDataSource(). What am I missing? TIA

[GabrielA]

Chart FX doesn't need the conection to be opened, it just need access to the sql Resulset.  Try to go through the data in the resulset after the conection is closed to be sure you are not passing an empty rs to the chart.

[bfollek]

Thanks. I'm trying to pinpoint when the ChartServer object actually reads the ResultSet. This seems to be at getHtmlData() time.

This matters for jdbc cleanup. Closing the connection, but hoping the resultset will still be there...I wouldn't want to depend on that behavior. At any rate, I like to explicitly close the resultset, then the stmt, then the connection.  

[GabrielA]

Yes, the resulset is read when you call either getHtmlData or getHtmlTag.  The problem you will find is that there is no way to close them after you call getHtmlData.

Bu you can use getHtmlDataEx, which will give you the chart stream, then you can close all object and send the chart to the browser when you are finished.  There are some getHtmlDataEx samples in the sample\misc folder of the installation.

[bfollek]

>... there is no way to close them after you call getHtmlData.

 I'm calling getHtmlData() in a try block, and closing the jdbc objects in the finally block. Seems to be working - print statements in the finally block go to the console, so I know it's running.