Exporting smartgwt grid data to csv

I needed the feature to export the ListGrid Data to Excel file, but this feature is available only for smargwt PRO and EE version. I explored if there is any way can download through js, since the data is already present with client. but couldn't find because Javascript by design do not have access to local disk. and some browsers has limited support for data URI.

so I decided to send the content back to server (I feel its not correct way), and servlet write back data.

here is example for adding context menu to grid with export options.


import com.google.gwt.user.client.ui.FormPanel;
import com.google.gwt.user.client.ui.Hidden;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.smartgwt.client.types.Autofit;
import com.smartgwt.client.types.ListGridFieldType;
import com.smartgwt.client.types.SelectionStyle;
import com.smartgwt.client.widgets.grid.ListGrid;
import com.smartgwt.client.widgets.grid.ListGridField;
import com.smartgwt.client.widgets.grid.ListGridRecord;
import com.smartgwt.client.widgets.menu.Menu;
import com.smartgwt.client.widgets.menu.MenuItem;
import com.smartgwt.client.widgets.menu.events.ClickHandler;
import com.smartgwt.client.widgets.menu.events.MenuItemClickEvent;

public class ExportableGrid extends ListGrid{
    public ListGridRecord[] records;

    public ExportableGrid() {
        setHeight100();
        setWidth100();
       
        addContextMenu();
       
    }
   
    private StringBuilder exportCSV(boolean all) {
        StringBuilder stringBuilder = new StringBuilder(); // csv data in here
        ListGridField[] fields = getFields();
        for (int i = 0; i < fields.length; i++) {
            ListGridField listGridField = fields[i];
            if(!listGridField.getType().equals(ListGridFieldType.IMAGE) && !listGridField.getName().equalsIgnoreCase("$72V")) {
                stringBuilder.append("\"");
                stringBuilder.append(listGridField.getName().toUpperCase());
                stringBuilder.append("\",");
            }
        }
        stringBuilder.deleteCharAt(stringBuilder.length() - 1); // remove last
        stringBuilder.append("\n");

        ListGridRecord[] recs = null;
        if (all) {
            recs = getRecords();
        } else {
            recs = getSelection();
        }
        for (int i = 0; i < recs.length; i++) {
            ListGridRecord listGridRecord = recs[i];
            ListGridField[] listGridFields = getFields();
            for (int j = 0; j < listGridFields.length; j++) {
                ListGridField listGridField = listGridFields[j];
                if(!listGridField.getType().equals(ListGridFieldType.IMAGE) && !listGridField.getName().equalsIgnoreCase("$72V")) {
                    stringBuilder.append("\"");
                    String val = listGridRecord.getAttribute(listGridField.getName());
                    stringBuilder.append(val);
                    stringBuilder.append("\",");
                }
            }
            stringBuilder.deleteCharAt(stringBuilder.length() - 1); // remove last ","
            stringBuilder.append("\n");
        }
        return stringBuilder;
    }
   
    public void export(StringBuilder stringBuilder, String fileExt) {   
        final FormPanel formPanel = new FormPanel();
        formPanel.setAction(getExportFileUrl());
        formPanel.setMethod(FormPanel.METHOD_POST);
       
        VerticalPanel verticalPanel = new VerticalPanel();
   
        Hidden data = new Hidden();
        data.setName("exprtData");
        data.setValue(stringBuilder.toString());
        verticalPanel.add(data);
       
        Hidden exportType = new Hidden();
        exportType.setName("exportType");
        exportType.setValue("clientExport");
        verticalPanel.add(exportType);
       
        Hidden fileType = new Hidden();
        fileType.setName("fileType");
        fileType.setValue(fileExt);
        verticalPanel.add(fileType);
   
        formPanel.add(verticalPanel);
        formPanel.setVisible(false);
        RootPanel.get().add(formPanel);   
        formPanel.submit();
       
    }
   
    public void addContextMenu() {
        setCanDragSelect(true); 
        setSelectionType(SelectionStyle.MULTIPLE);
        setAutoFitData(Autofit.VERTICAL); 
        setShowRollOver(false);
       
        MenuItem csvAll = new MenuItem("Export all as CSV");
        csvAll.addClickHandler(new ClickHandler() {
            @Override
            public void onClick(MenuItemClickEvent event) {
                export(exportCSV(true), "csv");
            }
        });
       
        MenuItem csvSelected = new MenuItem("Export selected as CSV");
        csvSelected.addClickHandler(new ClickHandler() {
            @Override
            public void onClick(MenuItemClickEvent event) {
                export(exportCSV(false), "csv");
            }
        });
       
        Menu menu = new Menu(); 
        menu.setWidth(150); 
        menu.addItem(csvAll); 
        menu.addItem(csvSelected); 
       
        setContextMenu(menu);
    }
   
    private String getExportFileUrl() {
        StringBuilder urlBuilder = new StringBuilder("exportFiles/exportFiles.htm?");
        return urlBuilder.toString();
    }
   
    public void updateData() {
        records = new ListGridRecord[2];
        for (int i=0; i            records[i] = new ListGridRecord();
            records[i].setAttribute("Test", "Test"+i);
        }
    }
}

My server side controller looks like below...

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class Exporter extends AbstractController {

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
        String exportType = request.getParameter("exportType");
        if(exportType != null && exportType.equalsIgnoreCase("clientExport")){
            String fileType = request.getParameter("fileType");
            String exportData = request.getParameter("exprtData");
            byte[] bytes = exportData.getBytes();
            response.setContentLength((int) bytes.length);
            response.setHeader("Content-type" ,"application/"+fileType);
            String fileNameHeader = "attachment; filename=download."+fileType ;
            response.setHeader("Content-disposition" , fileNameHeader); 
            ServletOutputStream  stream = response.getOutputStream();   
            stream.write(bytes);
        }
        return null;
    }
}