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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();

}

}

}

}

}

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