我想用Java打印一个表，但实现Printable类的类打印一页，当我的表很大时，将其分成两页，然后打印最后一页。如果有更多页面打印所有页面，我就不会打印一页。
这是我的TablePrintable类：
class TablePrintable implements Printable {
/** The table to print. */
private JTable table;
/** For quick reference to the table's header. */
private JTableHeader header;
/** For quick reference to the table's column model. */
private TableColumnModel colModel;
/** To save multiple calculations of total column width. */
private int totalColWidth;
/** The printing mode of this printable. */
private JTable.PrintMode printMode;
/** Provides the header text for the table. */
private MessageFormat headerFormat;
/** Provides the footer text for the table. */
private MessageFormat footerFormat;
/** The most recent page index asked to print. */
private int last = -1;
/** The next row to print. */
private int row = 0;
/** The next column to print. */
private int col = 0;
/** Used to store an area of the table to be printed. */
private final Rectangle clip = new Rectangle(0, 0, 0, 0);
/** Used to store an area of the table's header to be printed. */
private final Rectangle hclip = new Rectangle(0, 0, 0, 0);
/** Saves the creation of multiple rectangles. */
private final Rectangle tempRect = new Rectangle(0, 0, 0, 0);
/** Vertical space to leave between table and header/footer text. */
private static final int H_F_SPACE = 15;
/** Font size for the header text. */
private static final float HEADER_FONT_SIZE = 14.0f;
/** Font size for the footer text. */
private static final float FOOTER_FONT_SIZE = 10.0f;
/** The font to use in rendering header text. */
private Font headerFont;
/** The font to use in rendering footer text. */
private Font footerFont;
/**
* Create a new <code>TablePrintable</code> for the given
* <code>JTable</code>. Header and footer text can be specified using the
* two <code>MessageFormat</code> parameters. When called upon to provide a
* String, each format is given the current page number.
*
* @param table
* the table to print
* @param printMode
* the printing mode for this printable
* @param headerFormat
* a <code>MessageFormat</code> specifying the text to be used in
* printing a header, or null for none
* @param footerFormat
* a <code>MessageFormat</code> specifying the text to be used in
* printing a footer, or null for none
* @throws IllegalArgumentException
* if passed an invalid print mode
*/
public TablePrintable(JTable table, JTable.PrintMode printMode,
MessageFormat headerFormat,
MessageFormat footerFormat) {
this.table = table;
header = table.getTableHeader();
colModel = table.getColumnModel();
totalColWidth = colModel.getTotalColumnWidth();
if (header != null) {
// the header clip height can be set once since it's unchanging
hclip.height = header.getHeight();
}
this.printMode = printMode;
this.headerFormat = headerFormat;
this.footerFormat = footerFormat;
// derive the header and footer font from the table's font
headerFont = table.getFont().deriveFont(Font.BOLD, HEADER_FONT_SIZE);
footerFont = table.getFont().deriveFont(Font.PLAIN, FOOTER_FONT_SIZE);
}
/**
* Prints the specified page of the table into the given {@link Graphics}
* context, in the specified format.
*
* @param graphics
* the context into which the page is drawn
* @param pageFormat
* the size and orientation of the page being drawn
* @param pageIndex
* the zero based index of the page to be drawn
* @return PAGE_EXISTS if the page is rendered successfully, or NO_SUCH_PAGE
* if a non-existent page index is specified
* @throws PrinterException
* if an error causes printing to be aborted
*/
@Override
public int print(Graphics graphics, PageFormat pageFormat, int pageIndex)
throws PrinterException {
// for easy access to these values
final int imgWidth = (int) pageFormat.getImageableWidth();
final int imgHeight = (int) pageFormat.getImageableHeight();
if (imgWidth <= 0) {
throw new PrinterException("Width of printable area is too small.");
}
if((table.getRowCount() * table.getRowHeight()) > imgHeight){
pageIndex++;
}
// to pass the page number when formatting the header and footer text
Object[] pageNumber = new Object[] { new Integer(pageIndex + 1) };
// fetch the formatted header text, if any
String headerText = null;
if (headerFormat != null) {
headerText = headerFormat.format(pageNumber);
}
// fetch the formatted footer text, if any
String footerText = null;
if (footerFormat != null) {
footerText = footerFormat.format(pageNumber);
}
// to store the bounds of the header and footer text
Rectangle2D hRect = null;
Rectangle2D fRect = null;
// the amount of vertical space needed for the header and footer text
int headerTextSpace = 0;
int footerTextSpace = 0;
// the amount of vertical space available for printing the table
int availableSpace = imgHeight;
System.out.println("available space: " + availableSpace);
System.out.println("the avail space // row Height => " +
(availableSpace/table.getRowHeight()));
// if there's header text, find out how much space is needed for it
// and subtract that from the available space
if (headerText != null) {
graphics.setFont(headerFont);
hRect = graphics.getFontMetrics().getStringBounds(headerText,
graphics);
headerTextSpace = (int) Math.ceil(hRect.getHeight());
availableSpace -= headerTextSpace + H_F_SPACE;
}
// if there's footer text, find out how much space is needed for it
// and subtract that from the available space
if (footerText != null) {
graphics.setFont(footerFont);
fRect = graphics.getFontMetrics().getStringBounds(footerText,
graphics);
footerTextSpace = (int) Math.ceil(fRect.getHeight());
availableSpace -= footerTextSpace;// TODO
}
if (availableSpace <= 0) {
throw new PrinterException("Height of printable area is too
small.");
}
// depending on the print mode, we may need a scale factor to
// fit the table's entire width on the page
double sf = 1.0D;
if (printMode == JTable.PrintMode.FIT_WIDTH && totalColWidth > imgWidth)
{
// if not, we would have thrown an acception previously
assert imgWidth > 0;
// it must be, according to the if-condition, since imgWidth > 0
assert totalColWidth > 1;
sf = (double) imgWidth / (double) totalColWidth;
}
// dictated by the previous two assertions
assert sf > 0;
// This is in a loop for two reasons:
// First, it allows us to catch up in case we're called starting
// with a non-zero pageIndex. Second, we know that we can be called
// for the same page multiple times. The condition of this while
// loop acts as a check, ensuring that we don't attempt to do the
// calculations again when we are called subsequent times for the
// same page.
while (last < pageIndex) {
// if we are finished all columns in all rows
if (row >= table.getRowCount() && col == 0) {
return NO_SUCH_PAGE;
}
// rather than multiplying every row and column by the scale factor
// in findNextClip, just pass a width and height that have already
// been divided by it
int scaledWidth = (int) (imgWidth / sf);
int scaledHeight = (int) ((availableSpace - hclip.height) / sf);
// calculate the area of the table to be printed for this page
findNextClip(scaledWidth, scaledHeight);
last++;
}
// translate into the co-ordinate system of the pageFormat
Graphics2D g2d = (Graphics2D) graphics;
g2d.translate(pageFormat.getImageableX(), pageFormat.getImageableY());
// to save and store the transform
AffineTransform oldTrans;
// if there's footer text, print it at the bottom of the imageable area
if (footerText != null) {
oldTrans = g2d.getTransform();
g2d.translate(0, imgHeight - footerTextSpace);
printFooterText(g2d, footerText, fRect, footerFont, imgWidth);
g2d.setTransform(oldTrans);
}
// if there's header text, print it at the top of the imageable area
// and then translate downwards
if (headerText != null) {
printHeaderText(g2d, headerText, hRect, headerFont, imgWidth);
g2d.translate(0, headerTextSpace + H_F_SPACE);
}
// constrain the table output to the available space
tempRect.x = 0;
tempRect.y = 0;
tempRect.width = imgWidth;
tempRect.height = availableSpace;
g2d.clip(tempRect);
// if we have a scale factor, scale the graphics object to fit
// the entire width
if (sf != 1.0D) {
g2d.scale(sf, sf);
// otherwise, ensure that the current portion of the table is
// centered horizontally
} else {
int diff = (imgWidth - clip.width) / 2;
g2d.translate(diff, 0);
}
// store the old transform and clip for later restoration
oldTrans = g2d.getTransform();
Shape oldClip = g2d.getClip();
// if there's a table header, print the current section and
// then translate downwards
if (header != null) {
hclip.x = clip.x;
hclip.width = clip.width;
g2d.translate(-hclip.x, 0);
g2d.clip(hclip);
header.print(g2d);
// restore the original transform and clip
g2d.setTransform(oldTrans);
g2d.setClip(oldClip);
// translate downwards
g2d.translate(0, hclip.height);
}
// print the current section of the table
g2d.translate(-clip.x, -clip.y);
g2d.clip(clip);
table.print(g2d);
// restore the original transform and clip
g2d.setTransform(oldTrans);
g2d.setClip(oldClip);
// draw a box around the table
g2d.setColor(Color.BLACK);
g2d.drawRect(0, 0, clip.width, hclip.height + clip.height);
return PAGE_EXISTS;
}
/**
* A helper method that encapsulates common code for rendering the header
* and footer text.
*
* @param g2d
* the graphics to draw into
* @param text
* the text to draw, non null
* @param rect
* the bounding rectangle for this text, as calculated at the
* given font, non null
* @param font
* the font to draw the text in, non null
* @param imgWidth
* the width of the area to draw into
*/
private void printHeaderText(Graphics2D g2d, String text, Rectangle2D rect,
Font font, int imgWidth) {
int tx;// TODO
// if the text is small enough to fit, center it
if (rect.getWidth() < imgWidth) {
tx = (int) ((imgWidth - rect.getWidth()) / 2);
// otherwise, if the table is LTR, ensure the left side of
// the text shows; the right can be clipped
} else if (table.getComponentOrientation().isLeftToRight()) {
tx = 0;
// otherwise, ensure the right side of the text shows
} else {
tx = -(int) (Math.ceil(rect.getWidth()) - imgWidth);
}
int ty = (int) Math.ceil(Math.abs(rect.getY()));
g2d.setColor(Color.BLACK);
g2d.setFont(MainUi.fLiner);
g2d.drawString(text, tx, ty);
}
private void printFooterText(Graphics2D g2d, String text, Rectangle2D rect,
Font font, int imgWidth) {
int tx;// TODO
// if the text is small enough to fit, center it
if (rect.getWidth() < imgWidth) {
tx = (int) ((imgWidth - rect.getWidth()) / 2);
// otherwise, if the table is LTR, ensure the left side of
// the text shows; the right can be clipped
} else if (table.getComponentOrientation().isLeftToRight()) {
tx = 0;
// otherwise, ensure the right side of the text shows
} else {
tx = -(int) (Math.ceil(rect.getWidth()) - imgWidth);
}
// int ty = (int) Math.ceil(Math.abs(rect.getY() + 30));
int ty = (int) Math.ceil(rect.getHeight());
g2d.setColor(Color.BLACK);
g2d.setFont(MainUi.ffLiner);
g2d.drawString(text, tx, ty-3);
}
/**
* Calculate the area of the table to be printed for the next page. This
* should only be called if there are rows and columns left to print.
*
* To avoid an infinite loop in printing, this will always put at least one
* cell on each page.
*
* @param pw
* the width of the area to print in
* @param ph
* the height of the area to print in
*/
private void findNextClip(int pw, int ph) {
final boolean ltr = table.getComponentOrientation().isLeftToRight();
// if we're ready to start a new set of rows
if (col == 0) {
if (ltr) {
// adjust clip to the left of the first column
clip.x = 0;
} else {
// adjust clip to the right of the first column
clip.x = totalColWidth;
}
// adjust clip to the top of the next set of rows
clip.y += clip.height;
// adjust clip width and height to be zero
clip.width = 0;
clip.height = 0;
// fit as many rows as possible, and at least one
int rowCount = table.getRowCount();
int rowHeight = table.getRowHeight(row);
do {
clip.height += rowHeight;
if (++row >= rowCount) {
break;
}
rowHeight = table.getRowHeight(row);
} while (clip.height + rowHeight <= ph);
}
// we can short-circuit for JTable.PrintMode.FIT_WIDTH since
// we'll always fit all columns on the page
if (printMode == JTable.PrintMode.FIT_WIDTH) {
clip.x = 0;
clip.width = totalColWidth;
return;
}
if (ltr) {
// adjust clip to the left of the next set of columns
clip.x += clip.width;
}
// adjust clip width to be zero
clip.width = 0;
// fit as many columns as possible, and at least one
int colCount = table.getColumnCount();
int colWidth = colModel.getColumn(col).getWidth();
do {
clip.width += colWidth;
if (!ltr) {
clip.x -= colWidth;
}
if (++col >= colCount) {
// reset col to 0 to indicate we're finished all columns
col = 0;
break;
}
colWidth = colModel.getColumn(col).getWidth();
} while (clip.width + colWidth <= pw);
}
}