Write file on client system using applet

I want to write a 开发者_开发问答file on client using applet. I have some it can write when we run the applet as separate from Java. But it can't write through browser by calling the applet function from javascript.

How can I write files on client system?

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Basically, there are two (practical) ways to write files to the client file system from an applet.

1. A digitally signed, trusted applet.
2. A Plug-In 2 applet that uses the JNLP API services.