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;
/**
* 使用了原始的分页方式去渲染JTextArea，提供了打印预览机制。
* <p>
* 事实上，我们还可以通过其他方式打印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("rint This TextArea");
  printButton.setName("printButton");
  printButton.addActionListener(this);
  JButton printPreviewButton = new JButton("rint 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("rint 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("rint TextArea");// 出现在系统打印任务列表
  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 + 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, "rint 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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