代碼如下：
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.print.PageFormat;
import java.awt.print.Printable;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
/**
* 使用了原始的分頁方式去渲染JTextArea，提供了打印預覽機制。
* <p>
* 事實上，我們還可以通過其他方式打印JTextArea：
* <ol>
* <li>{@code Component.print(Graphics g);} or
* {@code Component.printAll(Graphics g);}</li>
* <li>{@code Component.paint(Graphics g);} or
* {@code Component.paintAll(Graphics g);} whose rending may be slightly
* different to the previous method (for example, <code>JFrame</code>)</li>
* <li>{@code JTable.print();} or {@code JTextComponent.print();} provide
* especially powerful and convenient printing mechanism</li>
* </ol>
*
* @author Gaowen
*/
public class PrintUIComponent extends JPanel implements ActionListener,
Printable {
private static final long serialVersionUID = 4797002827940419724L;
private static JFrame frame;
private JTextArea textAreaToPrint;
private PrinterJob job;
private int[] pageBreaks;// array of page break line positions
private String[] textLines;
private Header header;
public PrintUIComponent() {
super(new BorderLayout());
textAreaToPrint = new JTextArea(50, 20);
for (int i = 1; i <= 50; i++) {
textAreaToPrint.append("Line " + i + "\n");
}
JScrollPane scrollPane = new JScrollPane(textAreaToPrint);
scrollPane.setPreferredSize(new Dimension(250, 200));
add(scrollPane, BorderLayout.CENTER);
JButton printButton = new JButton("Print This TextArea");
printButton.setName("printButton");
printButton.addActionListener(this);
JButton printPreviewButton = new JButton("Print Preview");
printPreviewButton.setName("printPreviewButton");
printPreviewButton.addActionListener(this);
JPanel buttonGroup = new JPanel(new GridLayout(2, 1));
buttonGroup.add(printButton);
buttonGroup.add(printPreviewButton);
add(buttonGroup, BorderLayout.SOUTH);
/* Initialize PrinterJob */
initPrinterJob();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
frame = new JFrame("Print UI Example");
frame.setContentPane(new PrintUIComponent());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setVisible(true);
}
private void initTextLines() {
Document doc = textAreaToPrint.getDocument();
try {
String text = doc.getText(0, doc.getLength());
textLines = text.split("\n");
} catch (BadLocationException e) {
e.printStackTrace();
}
}
private void initPrinterJob() {
job = PrinterJob.getPrinterJob();
job.setJobName("Print TextArea");// 出現在系統打印任務列表
job.setPrintable(this);
}
@Override
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex)
throws PrinterException {
/*
* It is safe to use a copy of this graphics as this will not involve
* changes to it.
*/
Graphics2D g2 = (Graphics2D) graphics.create();
/* Calculate "pageBreaks" */
Font font = new Font("Serif", Font.PLAIN, 12);
FontMetrics metrics = g2.getFontMetrics(font);
int lineHeight = metrics.getHeight();
if (pageBreaks == null) {
initTextLines();
int linesPerPage = (int) (pageFormat.getImageableHeight() / lineHeight);
int numBreaks = (textLines.length - 1) / linesPerPage;
pageBreaks = new int[numBreaks];
for (int b = 0; b < numBreaks; b++) {
pageBreaks[b] = (b + 1) * linesPerPage;
}
}
/* Condition to exit printing */
if (pageIndex > pageBreaks.length) {
return NO_SUCH_PAGE;
}
/* (0,0) is outside the imageable area, translate to avoid clipping */
g2.translate(pageFormat.getImageableX(), pageFormat.getImageableY());
/* Draw each line that is on this page */
int y = 0;
int start = (pageIndex == 0) ? 0 : pageBreaks[pageIndex - 1];
int end = (pageIndex == pageBreaks.length) ? textLines.length
: pageBreaks[pageIndex];
for (int line = start; line < end; line++) {
y += lineHeight;
g2.drawString(textLines[line], 0, y);
}
/* dispose of the graphics copy */
g2.dispose();
/* Tell the caller that this page is part of the printed document */
return PAGE_EXISTS;
}
@Override
public void actionPerformed(ActionEvent e) {
Object actionEventSource = e.getSource();
if (actionEventSource instanceof JButton) {
JButton button = (JButton) actionEventSource;
if (button.getName().equals("printButton")) {
pageBreaks = null;// reset pagination
boolean ok = job.printDialog();
if (ok) {
try {
job.print();
} catch (PrinterException ex) {
/* The job did not successfully complete */
ex.printStackTrace();
}
}
} else if (button.getName().equals("printPreviewButton")) {
pageBreaks = null;// reset pagination
createAndShowPreviewDialog();
}
}
}
private void createAndShowPreviewDialog() {
JDialog previewDialog = new JDialog(frame, "Print Preview Dialog", true);
JPanel contentPane = new JPanel(new BorderLayout());
PreviewArea previewArea = new PreviewArea();
previewArea.addMouseListener(new PreviewAreaMouseAdapter(previewArea));
JScrollPane scrollPane = new JScrollPane(previewArea);
contentPane.add(scrollPane, BorderLayout.CENTER);
header = new Header(previewArea);
contentPane.add(header, BorderLayout.NORTH);
previewDialog.setContentPane(contentPane);
previewDialog.setSize(600, 600);
previewDialog
.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
previewDialog.setVisible(true);
}
private class Header extends Component {
private static final long serialVersionUID = -1741188309769027249L;
private PreviewArea previewArea;
private boolean paintable;
private Header(PreviewArea previewArea) {
this.previewArea = previewArea;
}
private void setPaintable(boolean paintable) {
this.paintable = paintable;
}
@Override
public void paint(Graphics g) {
if (paintable) {
g.setColor(Color.GRAY);
g.drawString(
String.valueOf(previewArea.getPageIndex() + 1)
+ "/"
+ String.valueOf(pageBreaks.length + 1)
+ " pages (Click left mouse button to preview next page; right to previous)",
10, 15);
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(super.getPreferredSize().width, 20);
}
}
private class PreviewArea extends Component {
private static final long serialVersionUID = -6384174997251439843L;
private PageFormat pageFormat;
private int pageIndex;
private int w;
private int h;
private final int marginX = 10;
private final int marginY = 20;
private PreviewArea() {
pageFormat = job.pageDialog(job.defaultPage());
pageIndex = 0;
w = (int) pageFormat.getWidth();
h = (int) pageFormat.getHeight();
}
private int getPageIndex() {
return pageIndex;
}
private void setPageIndex(int pageIndex) {
this.pageIndex = pageIndex;
}
@Override
public Dimension getPreferredSize() {
return new Dimension(w + 2 * marginX, h + 2 * marginY);
}
@Override
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g.create();
g2.translate(marginX, marginY);
g2.drawRect(0, 0, w, h);
int ix = (int) (pageFormat.getImageableX() - 1);
int iy = (int) (pageFormat.getImageableY() - 1);
int iw = (int) (pageFormat.getImageableWidth() + 1);
int ih = (int) (pageFormat.getImageableHeight() + 1);
g2.setStroke(new BasicStroke(1f, BasicStroke.CAP_ROUND,
BasicStroke.JOIN_ROUND, 10f, new float[] { 5, 5 }, 0f));
g2.drawRect(ix, iy, iw, ih);
try {
PrintUIComponent.this.print(g2, pageFormat, pageIndex);
} catch (PrinterException e) {
e.printStackTrace();
}
g2.dispose();
header.setPaintable(true);
header.repaint();
}
}
private class PreviewAreaMouseAdapter extends MouseAdapter {
private PreviewArea previewArea;
private PreviewAreaMouseAdapter(PreviewArea previewArea) {
this.previewArea = previewArea;
}
@Override
public void mouseClicked(MouseEvent e) {
int currentIndex = previewArea.getPageIndex();
if (e.getButton() == MouseEvent.BUTTON1) {
/* next page */
if (currentIndex < pageBreaks.length) {
previewArea.setPageIndex(currentIndex + 1);
previewArea.repaint();
}
} else if (e.getButton() == MouseEvent.BUTTON3) {
/* previous page */
if (currentIndex > 0) {
previewArea.setPageIndex(currentIndex - 1);
previewArea.repaint();
}
}
}
}
}
