File download button on a jsp page that does the download without taking you to another page.

[Heena Agarwal]

Greetings,

First of all, I'm not sure whether I should have posted this question in struts or in jsp forum as I'm not aware if it is something that can/should be handled with jsp and scriptlet combination, jsp/javascript combination or if struts has a cool tag library that can handle file download. Could you please move the topic to appropriate forum depending on where it'd better be.

My webpage needs to have a button that lets the user download a sample file from the server. And it needs to have a button that lets the user upload such a file with data. The upload part is working fine. It's the download that I'm having trouble with. This is how the upload part is working.

My form has a FormFile type field which is set in the jsp as follows.

                         <tr>
                		<td class="formLabel"><label for="file">CSV File:</label></td>
                		<td><html:file property="importFile" styleId="importFile" size="60" maxlength="120" /></td>
               		</tr>
                	<tr>
                		<td  class="spacerCell"> </td>
               		</tr>

My struts-config is as follows.

		 <action path="/importSomething"  roles="SHIMA_SysAdmin, SHIMA_UserAdmin, MTIMA_SysAdmin, MTIMA_UserAdmin" 
		  name="SomethingForm"
		  scope="request"
		  type="com.abc.imauditor.controller.action.something.SomethingImportAction"
		  parameter="method">
		  <forward name="load" 	path="importSomething"/>
		  <forward name="ROLEANDGROUP" 	path="importSomethingGetRoleAndGroup"/>
		  <forward name="popup_choose_groups" 	path="/jsp/Something/popup_choose_groups.jsp"/>
		  
		 </action>

Relevant part in tiles-defs is as follows.

	<definition name="importSomething" extends="headerBase">
		<put name="title" type="string" direct="true" value="title.importSomething" />
		<put name="body" value="/jsp/employees/importSomethingMain.jsp" />
		<put name="menuValue" value="something" />
	</definition>

My form class doesn't need run any grand logic or something to do the upload. It just has the following import.

import org.apache.struts.upload.FormFile;

and has the usual setter for a FormFile type variable as follows.

	public void setImportFile(FormFile importFile) {
		this.importFile =importFile;
	}

And my action method invokes this setter. And there is no other logic I need write for the upload to work.

Isn't there something like FormFile that struts already has for the download to also work? Is there a link or a tutorial I could read?

I checked on web for "how to download a file from jsp" and almost everyone uses an

<a >download a sample file</a>

tag and then creates the download.jsp that has a big scriptlet code that creates an output stream. I've tried this. When I click on the link, my page changes. This is not what I want. Plus the downloading does not happen ( but I will resolve this part later ). And the existing jsps don't use grand scriptlets so I am not sure if it's a good practice to embed lot of Java code within a JSP.

Doesn't struts have some elegant way for the download too?
Sorry if I didn't specify something that is required. I'm very new to the UI components. So I don't know much. Let me know if I need to provide more information.

I'm fine with trying out anything that's available- tutorials, links, books, hints, .. so long as I can get it working in the end.

Thanks.

[Heena Agarwal]

For some reason, the editor won't let me type the "<a href" tag correctly.

[Paul Clapham]

When you post, look below the box where you are typing and you'll see there are some checkboxes. Since you want to type HTML, you'll want to check the "Disable HTML in this message" checkbox. If you don't, then the forum software will attempt to evaluate the HTML you entered rather than just echoing it.

I edited your other posts and checked that box.

[Heena Agarwal]

Thanks, Paul. I'll keep that in mind.

Update: I'm going to be trying this tomorrow. Have found a couple of helpful links..
Hopefully one of those options will work.

I will keep this thread updated with whatever status I have tomorrow.

Thanks.

[Heena Agarwal]

This is resolved. Sorry I couldn't update this thread earlier than this.

What I did is this. Created a row in the jsp with a button as follows.

<tr>
<td class="formLabel"><label for="file">Download File:</label></td>
<td>
<span>
<a class="buttonStyle" href="importSomething.do?method=downLoadSampleCSV">Download Sample CSV</a>
</span>
</td>
<tr>

And added following code in the action class.

	/**
	 * @param mapping
	 * @param form
	 * @param request
	 * @param response
	 * @return
	 */
	public ActionForward downLoadSampleCSV(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response) 
	{ 
		FTLogChannel _log = null;
		try 
		{	
			_log = IMRUtils.initLog(getServlet().getServletContext(), 
					"Import something");
			String fileSeperator = System.getProperty("file.separator");
			String fileName = ".." + fileSeperator + "bin" + fileSeperator+
					"SomethingImportSampleCSV.csv";
			File file = new File(fileName);			
			if (!file.exists()) 
			{
				List errorList= new ArrayList();
				MessageBean msgBean = new MessageBean();
				msgBean.setType(IMAdminConstants.MSG_TYPE_ERROR);
				msgBean.setHeader("Sample File could not be downloaded");
				errorList.add(msgBean);
				return mapping.findForward("load");				
			} 
			else 
			{
				response= this.downLoadToDisk(request, response, file, _log );				
			}
	
		}
		catch(Exception e)
		{
			_log.warning("downLoadSampleCSV failed. Reason: "+ e.getCause() +
					" message: "+e.getMessage());
			IMAdminUtils.handleError(e, request, _log);
		}
	
		return null;
	}
	
	
	/**
	 * @param request
	 * @param response
	 * @param file
	 * @param _log
	 * @return
	 */
	public HttpServletResponse downLoadToDisk(HttpServletRequest request, 
			HttpServletResponse response, File file, FTLogChannel _log) 
	{
		try
		{
			InputStream in = new FileInputStream(file);
			ServletOutputStream  out   = response.getOutputStream();
			BufferedInputStream bIn = new BufferedInputStream(in);
			response.setContentType(request.getSession().getServletContext().
					getMimeType(file.getName()));
	    
			String agent = request.getHeader("USER-AGENT");
			String disposition = null;
	    
			if (agent != null && agent.indexOf("MSIE") != -1)
			{
				disposition = "attachment; filename=" + 
					URLEncoder.encode(file.getName(), "UTF-8");
			}
	    
			else if (agent != null && agent.indexOf("Mozilla") != -1)
			{
				disposition = "attachment; filename=" + 
					MimeUtility.encodeText(file.getName(),"UTF-8", "B");
			}
			response.setHeader("Content-disposition",disposition);
			BufferedOutputStream bos = new BufferedOutputStream(out);	             
			byte[] bArr = new byte[1024];
			int bytesRead;
	    
			int totBytes =  0;
	    
			while((bytesRead = bIn.read(bArr, 0, bArr.length)) != -1) 
			{
				totBytes += bytesRead;
				bos.write(bArr, 0, bytesRead);
			}
	    
			bos.close();	
	    
		}
		catch(Exception e)
		{
			_log.warning("downLoadToDisk failed. Reason: "+
					e.getCause() +" Message: "+e.getMessage());
		}
		return response;
	}