如何按列而不是按行输出primefaces DataGrid组件的数据(转置数据)

Question

Primefaces 5.0中有一个DataGrid组件。它显示按行分割的输入数据。如何显示按列分割的数据?

A B C       A D G
D E F  -->  B E H 
G H         C F 

Answer 1

我的解决方案是在Primefaces的DataGrid组件中置换数据是覆盖DataGridRenderer类的encodeTable()方法。

@Override
protected void encodeTable(FacesContext context, DataGrid grid) throws IOException {
    ResponseWriter writer = context.getResponseWriter();
    int columns = grid.getColumns();
    int firstRowIndex = grid.getFirst();
    int rowIndex = firstRowIndex;
    int rows = grid.getRows();
    int itemsToRender = rows != 0 ? rows : grid.getRowCount();
    int numberOfRowsToRender = (itemsToRender + columns - 1) / columns;
    String transpose = (String) grid.getAttributes().get("transpose");
    boolean isTranspose = transpose != null ? Boolean.valueOf(transpose) : false;
    writer.startElement("table", grid);
    writer.writeAttribute("class", DataGrid.TABLE_CLASS, null);
    writer.startElement("tbody", null);
    for (int i = 0; i < numberOfRowsToRender; i++) {
        writer.startElement("tr", null);
        writer.writeAttribute("class", DataGrid.TABLE_ROW_CLASS, null);
        for (int j = 0; j < columns; j++) {
            writer.startElement("td", null);
            writer.writeAttribute("class", DataGrid.TABLE_COLUMN_CLASS, null);
            if (isTranspose) {
                writer.writeAttribute("style", String.format("width: %d%%;", 100 / columns), null);
            }
            grid.setRowIndex(isTranspose ? numberOfRowsToRender * j + i + firstRowIndex : rowIndex);
            if (grid.isRowAvailable()) {
                renderChildren(context, grid);
            }
            rowIndex++;
            writer.endElement("td");
        }
        writer.endElement("tr");
    }
    grid.setRowIndex(-1);    //cleanup
    writer.endElement("tbody");
    writer.endElement("table");
}

并在faces-config.xml:

中注册Renderer元素

<render-kit>
    <renderer>
        <component-family>org.primefaces.component</component-family>
        <renderer-type>org.primefaces.component.DataGridRenderer</renderer-type>
        <renderer-class>org.primefaces.component.datagrid.TransposableDataGridRenderer</renderer-class>
    </renderer>
</render-kit>

现在我可以为<p:dataGrid>标签指定transposable="true"属性。代码还"修复"样式表，使每个页面具有相同数量的列，即使在最后一页上没有足够的数据来覆盖所有列。