我有一个名为的表table，其中填充了数据，我还有一个MessageFormat标题我想用作标题来打印JTable这是MessageFormat：
MessageFormat header = new MessageFormat("Product: "
+ task.getProductName() + " Job: "
+ task.getJobNumber() + " Task: " + task.getTaskID()
);
我想在标题中打印 3 行，一行用于 Product、Job 和 Task
我打印的方式table是这样的：
table.print(JTable.PrintMode.FIT_WIDTH, header, null);
我似乎无法弄清楚如何在 3 个单独的行中打印标题，我尝试使用\n创建一个新行，但这似乎不起作用。
这将是一个很长的答案（代码方面），因为我发现的唯一解决方案是实现自定义Printable. 当然下面的代码不是我自己写的，主要是把我从jdk源码中提取的代码复制过来，做了一些调整。
我们到了：
这就是您所说的调用 print 方法的方式：
DefaultTableModel dtm = new DefaultTableModel(new String[] { "Column 1" }, 1);
JTable table = new JTable(dtm) {
@Override
public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) {
return new TablePrintable(this, printMode, headerFormat, footerFormat);
}
};
以下课程在哪里TablePrintable（抱歉这里不简洁）：
static class TablePrintable implements Printable {
private final JTable table;
private final JTableHeader header;
private final TableColumnModel colModel;
private final int totalColWidth;
private final JTable.PrintMode printMode;
private final MessageFormat headerFormat;
private final MessageFormat footerFormat;
private int last = -1;
private int row = 0;
private int col = 0;
private final Rectangle clip = new Rectangle(0, 0, 0, 0);
private final Rectangle hclip = new Rectangle(0, 0, 0, 0);
private final Rectangle tempRect = new Rectangle(0, 0, 0, 0);
private static final int H_F_SPACE = 8;
private static final float HEADER_FONT_SIZE = 18.0f;
private static final float FOOTER_FONT_SIZE = 12.0f;
private final Font headerFont;
private final Font footerFont;
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);
}
@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.");
}
// to pass the page number when formatting the header and footer
// text
Object[] pageNumber = new Object[] { Integer.valueOf(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;
// 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);
int nbLines = headerText.split("\n").length;
hRect = graphics.getFontMetrics().getStringBounds(headerText, graphics);
hRect = new Rectangle2D.Double(hRect.getX(), Math.abs(hRect.getY()), hRect.getWidth(),
hRect.getHeight() * nbLines);
headerTextSpace = (int) Math.ceil(hRect.getHeight() * nbLines);
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 + H_F_SPACE;
}
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++;
}
// create a copy of the graphics so we don't affect the one given to
// us
Graphics2D g2d = (Graphics2D) graphics.create();
// translate into the co-ordinate system of the pageFormat
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);
String[] lines = footerText.split("\n");
printText(g2d, lines, 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) {
String[] lines = headerText.split("\n");
printText(g2d, lines, 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);
// dispose the graphics copy
g2d.dispose();
return PAGE_EXISTS;
}
private void printText(Graphics2D g2d, String[] lines, Rectangle2D rect, Font font, int imgWidth) {
g2d.setColor(Color.BLACK);
g2d.setFont(font);
for (int i = 0; i < lines.length; i++) {
int tx;
// if the text is small enough to fit, center it
if (rect.getWidth() < imgWidth) {
tx = (int) (imgWidth / 2 - g2d.getFontMetrics().getStringBounds(lines[i], g2d).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() + i * rect.getHeight() / lines.length));
g2d.drawString(lines[i], tx, ty);
}
}
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);
}
}
这是结果（我希望这是你所期望的）：
基本上，@aymeric 的答案是正确的：没有办法绕过自定义可打印实现。用稍微少一点的 c&p 来做到这一点的一种方法是有一个自定义实现
该方法的技巧是使用自定义 pageFormat 欺骗委托 tablePrintable 使其相信页面比实际小
如果您使用该getPrintable方法而不添加页眉/页脚文本，则可以Printable在其中包含/装饰返回的内容，您可以更好地控制页眉，并且可以指定多行页眉。请参阅该方法的javadoc，其中提到
将此 Printable 包装在另一个中以创建复杂的报告和文档是完全有效的。您甚至可以要求将不同的页面呈现到不同大小的可打印区域。实现必须准备好处理这个问题（可能通过动态进行布局计算）。但是，当 PrintMode.NORMAL 必须跨页面分布列时，为每个页面提供不同的高度可能无法很好地工作。
我没有足够的经验Printable来帮助您进一步了解如何实际执行此操作
你可以试试
StringBuilder builder = new StringBuilder();
builder.append("Product: ");
builder.append(task.getProductName());
builder.append(System.getProperty("line.separator"));
builder.append("Job: ");
builder.append(task.getJobNumber());
builder.append(System.getProperty("line.separator"));
builder.append("Task: ");
builder.append(task.getTaskID();
MessageFormat header = new MessageFormat(builder.toString());
如果这不起作用，那么您将不得不设置自己的打印机作业，并根据需要精确地布局标题。
我使用了两个MessageFormat数组作为该问题的巧妙解决方案。您会在下面找到最终结果的打印输出：
代码概述如下：
try
{
PrinterJob job = PrinterJob.getPrinterJob();
MessageFormat[] header = new MessageFormat[6];
// Assign the arrays with 6 String values for the headers
header[0] = new MessageFormat("");
header[1] = new MessageFormat(theExamSelection);
header[2] = new MessageFormat("");
header[3] = new MessageFormat("Scrud 60 - Grade Returns - Random Sample");
header[4] = new MessageFormat("");
header[5] = new MessageFormat(theSubjectSelection+" - "+theLevelSelection+" - "+thePaperSelection);
MessageFormat[] footer = new MessageFormat[4];
// Assign the 4 Strings to the footer array
footer[0] = new MessageFormat("Assistant Examiner Signature:______________ Date:___ /___ /_____ ");
footer[1] = new MessageFormat("");
footer[2] = new MessageFormat("");
footer[3] = new MessageFormat("Advising Examiner Signature:______________ Date:___ /___ /_____ ");
//here you place the JTable to print
// in this case its called randomSample_gradeBreakdown_jTable
// along with the header and footer arrays
job.setPrintable(new PrintTableMultiLine(randomSample_gradeBreakdown_jTable, JTable.PrintMode.FIT_WIDTH, header, footer ));
job.print();
}
catch (java.awt.print.PrinterException e)
{
System.err.format("Cannot print %s%n", e.getMessage());
JOptionPane.showMessageDialog(this,
"Check that your printer is working correctly","PRINT ERROR",JOptionPane.ERROR_MESSAGE
);
}