[Tapestry Wiki] Update of "Tapestry5HowToStreamAnExistingBinaryFile" by DanielJue

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The following page has been changed by DanielJue:
http://wiki.apache.org/tapestry/Tapestry5HowToStreamAnExistingBinaryFile

New page:
This example is very similar to the examples on Streaming a Dynamic PDF or a Dynamic chart.  Except in this case the file already exists somewhere.  I'll also show some utility classes I made up to assist in the process.

== ImagePage.java ==
This is the page class in your Tapestry 5 application
{{{
import java.io.InputStream;

import com.mycompany.myapp.wui.tapestry.services.util.JPEGAttachment;

import org.apache.tapestry.StreamResponse;
 public class ImagePage {
	public StreamResponse onSubmit() {
                //Note that you could provide an absolute path here, like H:\\LOLCATZ.MP3
		InputStream input = ImagePage.class.getResourceAsStream("HelloKitty.jpg"); 
		return new JPEGAttachment(input);
	}
}
}}}


== JPEGAttachment.java ==

{{{
import java.io.InputStream;

public class JPEGAttachment extends AttachmentStreamResponse {
	public JPEGAttachment(InputStream is, String args) {
		super(is, args);
		this.contentType = "image/jpeg";
		this.extension = "jpg";
	}

	public JPEGAttachment(InputStream is) {
		super(is);
		this.contentType = "image/jpeg";
		this.extension = "jpg";
	}
}
}}}




= AttachmentStreamResponse.java =
This is a util class for Attachments.  The goal here is to have a "Save As" dialog pop up on the client browser.

{{{

import java.io.IOException;
import java.io.InputStream;

import org.apache.tapestry.StreamResponse;
import org.apache.tapestry.services.Response;

public class AttachmentStreamResponse implements StreamResponse {
	private InputStream is = null;

	/**
	 * This can be changed to something obscure, so that it is more likely to trigger a "Save As" dialog, although there
	 * is no guarantee.
	 * 
	 * ex: application/x-download
	 * 
	 * See http://www.onjava.com/pub/a/onjava/excerpt/jebp_3/index3.html
	 */
	protected String contentType = "text/plain";

	protected String extension = "txt";

	protected String filename = "default";

	public AttachmentStreamResponse(InputStream is, String filenameIn) {
		this.is = is;
		if (filenameIn != null) {
			this.filename = filenameIn;
		}
	}

	public AttachmentStreamResponse(InputStream is) {
		this.is = is;
	}

	public String getContentType() {
		return contentType;
	}

	public InputStream getStream() throws IOException {
		return is;
	}

	public void prepareResponse(Response arg0) {
		arg0.setHeader("Content-Disposition", "attachment; filename=" + filename + ((extension == null) ? "" : ("." + extension)));
		arg0.setHeader("Expires", "0");
		arg0.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
		arg0.setHeader("Pragma", "public");
		//We can't set the length here because we only have an Input Stream at this point. (Although we'd like to.)
		//We can only get size from an output stream.  arg0.setContentLength(.length);
	}
}

}}}






= InlineStreamResponse.java =

This file is not used in the example, but is for files you intend to display inline in the browser (No "Save As" dialog box):
{{{


import java.io.IOException;
import java.io.InputStream;

import org.apache.tapestry.StreamResponse;
import org.apache.tapestry.services.Response;

public class InlineStreamResponse implements StreamResponse {
	private InputStream is = null;

	protected String contentType = "text/plain";// this is the default

	protected String extension = "txt";

	protected String filename = "default";

	public InlineStreamResponse(InputStream is, String... args) {
		this.is = is;
		if (args != null) {
			this.filename = args[0];
		}
	}

	public String getContentType() {
		return contentType;
	}

	public InputStream getStream() throws IOException {
		return is;
	}

	public void prepareResponse(Response arg0) {
		arg0.setHeader("Content-Disposition", "inline; filename=" + filename
				+ ((extension == null) ? "" : ("." + extension)));
	}
}

}}}

= Other file types =
Now, all you have to do for other file types is create a class like this:

== For a JPG inline ==
{{{
import java.io.InputStream;

public class JPEGInline extends InlineStreamResponse {
	public JPEGInline(InputStream is, String... args) {
		super(is, args);
		this.contentType = "image/jpeg";
		this.extension = "jpg";
	}
}
}}}

== For an XLS attachment ==
{{{
public class XLSAttachment extends AttachmentStreamResponse {
	public XLSAttachment(InputStream is, String args) {
		super(is, args);
		this.contentType = "application/vnd.ms-excel";
		this.extension = "xls";
	}
}
}}}

== For a PDF attachement ==
{{{
import java.io.InputStream;

public class PDFAttachment extends AttachmentStreamResponse {
	public PDFAttachment(InputStream is, String args) {
		super(is, args);
		this.contentType = "application/pdf";
		this.extension = "pdf";
	}

	public PDFAttachment(InputStream is) {
		super(is);
		this.contentType = "application/pdf";
		this.extension = "pdf";
	}
}
}}}

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