[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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