如何打印表格

1. Click the Launch button to run TablePrintDemo1 using Java™ Web Start (download JDK 7 or later). Alternatively, to compile and run the example yourself, consult the example index.
   
2. Each checkbox in the bottom part of the application window has a tool tip. Hold the cursor over a checkbox to find out its purpose.
3. Edit the text in the Header or Footer checkboxes or both to provide a different header or footer.
4. Clear the Header or Footer checkboxes or both to turn the header or footer off.
5. Clear the Show print dialog checkbox to turn the print dialog off.
6. Clear the Fit width to printed page checkbox to select printing in the NORMAL mode.
7. Clear the Interactive (Show status dialog) checkbox to turn the print dialog off.
8. Click the Print button to print the table according to the selected options.

Whenever a web-launched application tries to print, Java Web Start pops up a security dialog asking the user for permission to print. To proceed with printing, the user has to accept the request.

Note when you clear the Interactive checkbox, a message appears that warns the user about the disadvantage of printing non-interactively. You can find the printing code in the PrintGradesTable method. When called, this method first obtains the set of selected options from the GUI components and then calls the print method as follows.

boolean complete = gradesTable.print(mode, header, footer,
                                     showPrintDialog, null,
                                     interactive, null);

The value returned by the print method is then used to show either the success message or the message saying that the user cancelled printing.

Another important feature is the table printing API's use of table renderers. By using the table's renderers, the API provides a printed output that looks like the table on the screen. Look at the last column of the table on the screen. It contains custom images denoting the passed or failed status of each student. Now look at the printed result. You can see that the check and X marks look the same.

Here is a picture of the TablePrintDemo1 printed result in the FIT_WIDTH mode.

这个图已缩小以适合页面。
单击图像以其自然大小查看。

TablePrintDemo2 Example

The TablePrintDemo2 example is based on the previous demo and has an identical interface. The only difference is in the printed output. If you look at the TablePrintDemo1's printed result more attentively, you may notice that the check and X marks are fuzzy. The TablePrintDemo2 example shows how to customize the table to make the images more distinguishable in the table printout. In this demo, the overridden getTableCellRendererComponent method finds out whether the table is being printed and returns clearer black and white images. If the table is not being printed, it returns colored images that you can see on the screen.

Click the Launch button to run TablePrintDemo2 using Java™ Web Start (download JDK 7 or later). Alternatively, to compile and run the example yourself, consult the example index.

The isPaintingForPrint method defined in the JComponent class allows us to customize what we print compared with what we see on the screen. The code of the custom cell renderer, taken from TablePrintDemo2.java, is listed below. This code chooses which images to use depending on the value returned by the isPaintingForPrint method.

    /**
     * A custom cell renderer that extends TablePrinteDemo1's renderer, to instead
     * use clearer black and white versions of the icons when printing.
     */
    protected static class BWPassedColumnRenderer extends PassedColumnRenderer {
            public Component getTableCellRendererComponent(JTable table,
                                                           Object value,
                                                           boolean isSelected,
                                                           boolean hasFocus,
                                                           int row,
                                                           int column) {

            super.getTableCellRendererComponent(table, value, isSelected,
                                                hasFocus, row, column);

            /* if we're currently printing, use the black and white icons */
            if (table.isPaintingForPrint()) {
                boolean status = (Boolean)value;
                setIcon(status ? passedIconBW : failedIconBW);
            } /* otherwise, the superclass (colored) icons are used */

            return this;
        }
    }

Here is a picture of the TablePrintDemo2 printed result in the FIT_WIDTH mode.

这个图已缩小以适合页面。
单击图像以其自然大小查看。

TablePrintDemo3 Example

The TablePrintDemo3 example is based on the two previous demos. This example shows how to provide a customized Printable implementation by wrapping the default Printable with extra decoration. This demo has a similar interface but the Header and Footer checkboxes are disabled since the customized printable object will provide its own header and footer.

Click the Launch button to run TablePrintDemo3 using Java™ Web Start (download JDK 7 or later). Alternatively, to compile and run the example yourself, consult the example index.

This example prints the table inside an image of a clipboard. Here is a picture of the printed result in the FIT_WIDTH mode.

这个图已缩小以适合页面。
单击图像以其自然大小查看。

The entire code for this program can be found in TablePrintDemo3.java. In this demo, a custom subclass of the JTable class is used called FancyPrintingJTable. This FancyPrintingJTable class overrides the getPrintable method to return a custom printable object that wraps the default printable with its own decorations and header and footer. Here is the implementation of the getPrintable method.

public Printable getPrintable(PrintMode printMode,
                              MessageFormat headerFormat,
                              MessageFormat footerFormat) {

     MessageFormat pageNumber = new MessageFormat("- {0} -");

     /* Fetch the default printable */
     Printable delegate = super.getPrintable(printMode, null, pageNumber);

     /* Return a fancy printable that wraps the default */
     return new FancyPrintable(delegate);
}

The FancyPrintable class is responsible for wrapping the default printable object into another printable object and setting up the clipboard image. When an instance of this class is instantiated, it loads the images needed to assemble the clipboard image, calculates the area required for the clipboard image, calculates the shrunken area for the table, prints the table into the smaller area, and assembles and prints the clipboard image.

Pay attention to the flexibility of the code that assembles the clipboard image with respect to the page size. The code takes into account the actual page dimensions and puts together the auxiliary images, stretching some of them as necessary so that the final clipboard image fits the actual page size. The picture below shows the auxiliary images and indicates how those images form the final output.

这个图已缩小以适合页面。
单击图像以其自然大小查看。

The Table Printing API

This section lists methods defined in the JTable class that allow you to print tables.

Examples That Use Table Printing

This table lists examples that use table printing and points to where those examples are described.