org.tigris.scarab.screens
Class DataExport

java.lang.Object
  org.apache.turbine.modules.Module
      org.apache.turbine.modules.SecureModule
          org.apache.turbine.modules.screens.TemplateSecureScreen
              org.apache.turbine.TemplateSecureScreen
                  org.tigris.scarab.screens.Default
                      org.tigris.scarab.screens.DataExport

Direct Known Subclasses:

IssueListExport, ReportExport

class DataExport

extends Default

Sends file contents directly to the output stream, setting the Content-Type and writing back to the browser a tab-delimited file (Excel digests this fine). We used to use POI to compose an Excel binary data file, but its outrageous memory consumption didn't scale for large result sets. POI assembles the its output in memory. After study of the native OLE2 Excel file format, it appears very difficult to generate the file in another fashion.

Regards output encoding, for now we're assuming the response stream is appropriately set upon fetching. Also, we're assuming that Excel will do the right thing on receipt of our TSV file with Japanese or other multibyte characters (we're not setting an encoding on the Content-Type we return). Both of the above to be verified.

Since:

Scarab 1.0

Author:

John McNally, St.Ack, Daniel Rall

Nested Class Summary

protected class

DataExport.TSVPrinter Uses a PrintWriter internally to do actual writing.

Field Summary

protected static java.lang.String

NO_CONTENT What to show if a cell is empty.

Constructor Summary

(package private)

DataExport()

Method Summary

protected boolean	containsElements(java.util.List l)
void	doBuildTemplate(org.apache.turbine.RunData data, org.apache.turbine.TemplateContext context) Sets the Content-Type header for the response.
protected java.lang.String	escapeCommas(java.lang.String s) Escape any commas in passed string.
protected java.lang.String	getEncodingForExport(org.apache.turbine.RunData data) This function encapsulates the logic of determining which encoding to use.
protected java.io.Writer	getWriter(org.apache.turbine.RunData data) This function is available to subclasses -- it is used to provide a Writer based on the current request and the site configuration, taking encoding issues into consideration.

Methods inherited from class org.tigris.scarab.screens.Default

checkAuthorized, doBuild, getLocalizationTool, getScarabRequestTool, getTitle, isAuthorized, setTargetLogin, setTargetSelectModule

Methods inherited from class org.apache.turbine.modules.SecureModule

doBuildTemplate

Methods inherited from class org.apache.turbine.modules.Module

build, evaluate, execute, getPullService, getTemplateContext, getTemplateService, getTool, handleRequest, handleRequest, requestFinished, setTarget, setTemplate, templateExists

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_CONTENT

protected static final java.lang.String NO_CONTENT

What to show if a cell is empty. The empty string is dealt with best by spreadsheet applications.

See Also:

Constant Field Values

Constructor Detail

DataExport

DataExport()

Method Detail

doBuildTemplate

public void doBuildTemplate(org.apache.turbine.RunData data,
                            org.apache.turbine.TemplateContext context)
                     throws java.lang.Exception

Sets the Content-Type header for the response. Since this assumes we're writing the reponse ourself, indicates no target to render by setting it to null.

Overrides:

doBuildTemplate in class Default

Throws:

java.lang.Exception

getEncodingForExport

protected java.lang.String getEncodingForExport(org.apache.turbine.RunData data)

This function encapsulates the logic of determining which encoding to use. Right now, the encoding isn't per-request, but that should be changed.

getWriter

protected java.io.Writer getWriter(org.apache.turbine.RunData data)
                            throws java.io.IOException

This function is available to subclasses -- it is used to provide a Writer based on the current request and the site configuration, taking encoding issues into consideration.

Throws:

java.io.IOException

escapeCommas

protected java.lang.String escapeCommas(java.lang.String s)

Escape any commas in passed string.

Parameters:

s - String to check.

Returns:

Passed string with commas escaped.

containsElements

protected final boolean containsElements(java.util.List l)