It's my understanding that javax.servlet.ServletOutputStream extends java.io.OutputStream which, at least currently, defines the write method's return value to be void. What's interesting though is that the Java Tutorial claims it's int. See:
http://java.sun.com/docs/books/tutorial/essential/io/overview.html
Another interesting point is that even though the current JavaDoc for java.io.OutputStream defines the return value to be void, it includes the following line: "The general contract for write(b, off, len) is that some of the bytes in the array b are written...", the key word here being "some."
Would anyone care to comment on the history or reality of this API?
- Jim
The following message was taken from the Struts Mail Archive:
Response to: File upload/download design question ([EMAIL PROTECTED])
Date: Wed, 30 May 2001 20:08:25 -0700 (PDT) From: Craig R. McClanahan <[EMAIL PROTECTED]> Subject: File upload/download design question Content-Type: TEXT/PLAIN; charset=US-ASCII
On Wed, 25 Apr 2001 [EMAIL PROTECTED] wrote:
> > I have a design question regarding file upload/download which is not > completely Struts related but I was hoping someone could provide some > suggestions. I have succeeded with the upload using the struts upload > package, and then I load the file into an Oracle BLOB field. Now I need to > get it back to the user if they want to view it. > > I was planning to create an Action for processing the file download. The > user will click on a URL and pass in the ID of the file as a request > parameter to the Action (i.e. fileDownload.do?id=1234). The Action will > access a session EJB which then locates the requested file and returns it to > the Action as a File object. Here is where I need advice: what is the best > way to send this File back to the browser? Can I change the response type > to "file" somehow and stream this to the browser? Another option I thought > about was saving the file to a temp directory and then redirecting the > browser to this file. I would rather not write temp files if I don't have > to. Or, is there any functionality provided with struts for sending a file > back to the browser? >
This is one of the cases where you might actually want to have an Action create the response itself, instead of forwarding to a JSP page to do it. The reason for this is that JSP pages aren't meant for binary output (like a GIF image) -- but servlets can do this easily.
An example of an Action to do this might look like this:
byte buffer[] = ... load byte array from the database ... int size = xxx; // Number of bytes to be sent
response.setContentLength(size);
response.setContentType("image/gif"); // Or whatever is correct
ServletOutputStream stream = response.getOutputStream();
int sent = 0;
while (sent < size) {
int count = stream.write(buffer, sent, size - sent);
sent += count;
}
stream.flush();return (null);
Note that NULL is returned, instead of an ActionForward. This is the signal to the controller servlet that the Action has already created the response, so no forwarding is required.
> Any suggestions greatly appreciated... > > Thanks, > Bob >
Craig
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James Watkin
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The Anderson School at UCLA
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