GWT get CellTable contents for printing or export

Question 1

It seems there is no viable way to get the CellTable to give me the data for export without re-rendering contents. Since that would cost the same execution time as doing it myself, I resorted to rendering it myself. I used the following code to render HTML and display it in a new popup for printing. The print() method gets called from my Print button.

/**
 * Print in a new popup.
 * http://www.coderanch.com/t/564198/GWT/GWT-injecting-HTML-text-browser
 */
public static native void printHTMLString(String htmlString)/*-{
    var win = $wnd.open("_blank", "Print", "");
    win.document.open("text/html", "replace");
    win.document.write("<html><head></head><body>" + htmlString + "</body></html>");
    win.document.close();
    win.focus();
    var headID = win.document.getElementsByTagName("head")[0];
    var fileref = win.document.createElement("link");
    fileref.setAttribute("rel", "stylesheet");
    fileref.setAttribute("type", "text/css");
    fileref.setAttribute("href", "tables-min.css");
    headID.appendChild(fileref);
    win.print();
}-*/;

private void print() {
    //get the list from the ColumnSortHandler, so it keeps the sorting on the screen
    if (columnSortHandler.getList() == null || columnSortHandler.getList().isEmpty()) {
        Window.alert("Nothing to print");
        return;
    }

    SafeHtmlBuilder b = new SafeHtmlBuilder();
    b.appendHtmlConstant("<table class=\"pure-table\">"
            + "<thead><tr><th>Timestamp</th><th>Type</th><th>User</th>"
            + "<th>Screen</th><th>Client</th></tr></thead>");
    int count = 1;
    for (Record r : columnSortHandler.getList()) {
        b.appendHtmlConstant("<tr" + (count%2==0 ? ">" : " class='pure-table-odd'>"));

        b.appendHtmlConstant("<td>");
        b.appendEscaped(timestampFormat.format(timeStampColumn.getValue(r)));
        b.appendHtmlConstant("</td>");

        b.appendHtmlConstant("<td>");
        b.appendEscaped(typeColumn.getValue(r));
        b.appendHtmlConstant("</td>");

        b.appendHtmlConstant("<td>");
        b.appendEscaped(userColumn.getValue(r));
        b.appendHtmlConstant("</td>");

        b.appendHtmlConstant("<td>");
        b.appendEscaped(screenColumn.getValue(r));
        b.appendHtmlConstant("</td>");

        b.appendHtmlConstant("<td>");
        b.appendEscaped(clientColumn.getValue(r));
        b.appendHtmlConstant("</td>");


        b.appendHtmlConstant("</tr>");

        count++;
    }
    b.appendHtmlConstant("</table>");
    printHTMLString(b.toSafeHtml().asString());
}

Question 2

To export XLS use the class below.

To print use gwt-print-it.

The class below do that without server side.

public class TableToExcel {
    public static final <T> void save(final CellTable<T> table, String filename) {
        final AnchorElement a = Document.get().createAnchorElement();
        a.setHref("data:application/vnd.ms-excel;base64," + base64(table.getElement().getString()));
        a.setPropertyString("download", (filename.endsWith(".xls") || filename.endsWith(".xlsx")) ? filename : filename + ".xls");

        Document.get().getBody().appendChild(a);
        Scheduler.get().scheduleEntry(new ScheduledCommand() {
            @Override
            public void execute() {
                click(a);
                a.removeFromParent();
            }
        });
    }

    private static native void click(Element elem) /*-{
        elem.click();
    }-*/;

    public static native String base64(String data) /*-{
        return btoa(data);
    }-*/;
}

Question 3

You can use getInnerHTML or getInnerText

for(int i=0; i<cellTable.getRowCount();i++)
{
    TableRowElement rowElement = cellTable.getRowElement(i);
    for(int j =0; j<rowElement.getCells().getLength(); j++)
    {
        //System.out.println( rowElement.getCells().getItem(j).getInnerHTML() );
        System.out.println( rowElement.getCells().getItem(j).getInnerText() );

    }       
}

Question 4

You could try the gwt-table-to-excel module.

The main point is that excel and other modern spreadsheet knows how to render an html table, so just open the dynamically built html table with the correct mime-type, and that's all.

I never used it, but the description sounds good.