[ui/Charts] Explicitly close the image output-stream, using a try-with-resources

[martinvw]

Folloing the openHAB community topic:

https://community.openhab.org/t/java-io-ioexception-too-many-open-files/28204/10?u=martinvw

The current implementation is depending on:

This class provide means to properly close hanging
image input/output streams on VM shutdown.
This might be useful for proper cleanup such as removal
of temporary files.

Source: https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/com/sun/imageio/stream/StreamCloser.java#L34

The complete stack looks like
ChartServlet.java:280
ImageIO.java:1572
ImageIO.java:419
OutputStreamImageOutputStreamSpi.java:68
FileCacheImageOutputStream.java:95

[openhab-bot]

This pull request has been mentioned on openHAB Community. There might be relevant details there:

https://community.openhab.org/t/java-io-ioexception-too-many-open-files/28204/16

[martinvw]

See also this really old bug report which inspired me to solve it like this:

http://bugs.java.com/view_bug.do?bug_id=4894964

[kaikreuzer]

Excellent, thanks!

[openhab-bot]

This pull request has been mentioned on openHAB Community. There might be relevant details there:

https://community.openhab.org/t/static-conf-html-keeps-files-open/35788/6