可打印无法正常工作

本文介绍了可打印无法正常工作的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个系统，用户可以在该系统中注册学生，科目和每个科目的学生成绩，以及主题和日期.您可以通过输入学生的代码，然后从组合框中选择主题来搜索特定主题中的特定学生成绩.如果您进行搜索，这些内容将显示在jTable1中.

I have a system where the user can register students, subjects, and the student grade in each subject, together with the topic and the date. You can search a particular student grades in a particular subject by entering the code of the student, and by selecting the subject from a combobox. If you search it, those things are displayed in the jTable1.

然后，我有一个PRINT按钮.当用户单击打印"按钮时，jTable1中显示的内容将转到jTable2，这两个表之间的区别在于jTable1显示学生的姓名和主题名称，但是jTable2没有.为了更好的理解，这是一张照片:

Then, I have a PRINT button. When the user clicks the Print button, the content that is being displayed in the jTable1, goes to a jTable2, the difference between those 2 tables is that the jTable1 displays the name of the student, and the name of the subject, but the jTable2 doesn't. Here is a pic for better understanding:

i.stack.imgur/37SNh.png

因此，当用户单击按钮以打印jTable2时，我在此处使用此代码:

So, when the user clicked the button to Print the jTable2, I was using this code right here:

MessageFormat header = new MessageFormat("Ficha Pedagógica - "+jComboBox1.getSelectedItem()); MessageFormat footer = new MessageFormat("Página {0,number,integer}"); try{ jTable2.print(JTable.PrintMode.NORMAL, header, null); } catch(java.awt.print.PrinterException e){ System.out.println("error"); }

事实是，我希望打印两个标题，但是使用内置打印功能无法实现.因此，在堆栈溢出"中，我找到了这个主题:

The fact is, that I wanted 2 headlines to be printed, but such thing couldn't be achieved using the built-in print function. So, here in Stack Overflow, I found this topic:

如何使用使用JTable的MessageFormat

找到这个之后，我尝试使用那里给出的代码.因为我是一个初学者，所以即使代码中包含了所有注释，我也无法完全理解它.因此，我尝试实现它，但是现在，当我单击打印"按钮时，什么也没有发生.这是我的打印"按钮的代码:

After I found this, I tried using the code given there. Since I'm a beginner, even with all the comments in the code, I couldn't fully understand it. So, I tried to implement it, but now, when I click the "Print" button, nothing happens. This is my code of the Print button:

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) { // TODO add your handling code here: try{ Class.forName(driver); con = DriverManager.getConnection(str_conn,usuario,senha); stmt = con.createStatement(); sql = "select topico, nota, datanota from notas where notas.cod_aluno ="+jTextField1.getText()+" and notas.cod_curso ="+jTextField2.getText()+" order by notas.datanota"; rs = stmt.executeQuery(sql); if(rs == null){ return; } ResultSetMetaData rsmd; rsmd = rs.getMetaData(); Vector vetColuna = new Vector(); for(int i = 0;i<rsmd.getColumnCount();i++){ vetColuna.add(rsmd.getColumnLabel(i+1)); } Vector vetLinhas = new Vector(); while(rs.next()){ Vector vetLinha = new Vector(); for(int i = 0;i<rsmd.getColumnCount();i++){ vetLinha.add(rs.getObject(i+1)); } vetLinhas.add(vetLinha); jTable2.setModel(new DefaultTableModel(vetLinhas,vetColuna)); } }catch(ClassNotFoundException ex){ JOptionPane.showMessageDialog(null,"Erro\nNão foi possível carregar o driver."); System.out.println("Nao foi possivel carregar o driver"); ex.printStackTrace(); }catch(SQLException ex){ JOptionPane.showMessageDialog(null,"Erro\nCertifique-se de que todos os\ncampos estejam preenchidos corretamente."); System.out.println("Problema com o SQL"); ex.printStackTrace(); } /*MessageFormat header = new MessageFormat("Ficha Pedagógica - "+jComboBox1.getSelectedItem()); MessageFormat footer = new MessageFormat("Página {0,number,integer}"); try{ jTable2.print(JTable.PrintMode.NORMAL, header, null); } catch(java.awt.print.PrinterException e){ System.out.println("gsgd"); }*/ DefaultTableModel dtm = new DefaultTableModel(new String[] { "Column 1" }, 1); JTable jTable2 = new JTable(dtm) { @Override public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) { return new TablePrintable(this, printMode, headerFormat, footerFormat); } }; }

"TablePrintable"类的代码如下:

The code for the "TablePrintable" class is the following:

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); } }

但是，就像我说的那样，当我单击打印"按钮时，什么也没有发生.可能出什么问题了?

But, like I said, when I click the "print" button, nothing happens. What could be going wrong?

推荐答案

使用新修改的JTable，只需调用它的print方法即可.

With your newly modify JTable, you should only need to call it's print method.

DefaultTableModel dtm = new DefaultTableModel(new String[] { "Column 1" }, 1); JTable jTable2 = new JTable(dtm) { @Override public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) { return new TablePrintable(this, printMode, headerFormat, footerFormat); } }; try{ jTable2.print(JTable.PrintMode.NORMAL, header, null); } catch(java.awt.print.PrinterException e){ System.out.println("error"); }

由于您已经覆盖了getPrintable方法以返回自己的实现，因此这将用于物理打印表格...

Because you've overridden the getPrintable method to return your own implementation, this is what will be used to physically print the table...

已更新

标题文本需要用\n分隔，例如...

The header text needs to be separated by a \n, for example...

MessageFormat header = new MessageFormat("Testing, 01\n02\n03");

可以生产...

已更新

据我所知，在无法完全运行代码的情况下，您的打印代码应类似于...

As near as I can tell, without been able to fully run the code, your print code should look something like...

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) { Vector vetColuna = new Vector(); Vector vetLinhas = new Vector(); try { Class.forName(driver); con = DriverManager.getConnection(str_conn, usuario, senha); stmt = con.createStatement(); sql = "select topico, nota, datanota from notas where notas.cod_aluno =" + jTextField1.getText() + " and notas.cod_curso =" + jTextField2.getText() + " order by notas.datanota"; rs = stmt.executeQuery(sql); if (rs == null) { return; } ResultSetMetaData rsmd; rsmd = rs.getMetaData(); for (int i = 0; i < rsmd.getColumnCount(); i++) { vetColuna.add(rsmd.getColumnLabel(i + 1)); } while (rs.next()) { Vector vetLinha = new Vector(); for (int i = 0; i < rsmd.getColumnCount(); i++) { vetLinha.add(rs.getObject(i + 1)); } vetLinhas.add(vetLinha); } } catch (ClassNotFoundException ex) { JOptionPane.showMessageDialog(null, "Erro\nNão foi possível carregar o driver."); System.out.println("Nao foi possivel carregar o driver"); ex.printStackTrace(); } catch (SQLException ex) { JOptionPane.showMessageDialog(null, "Erro\nCertifique-se de que todos os\ncampos estejam preenchidos corretamente."); System.out.println("Problema com o SQL"); ex.printStackTrace(); } MessageFormat header = new MessageFormat("Ficha Pedagógica - " + jComboBox1.getSelectedItem() + "\nNome do Aluno - " + jTextField1.getText()); DefaultTableModel dtm = new DefaultTableModel(vetLinhas, vetColuna); JTable jTable2 = new JTable(dtm) { @Override public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) { return new TablePrintable(this, printMode, headerFormat, footerFormat); } }; try { jTable2.setSize(jTable2.getPreferredSize()); JTableHeader tableHeader = jTable2.getTableHeader(); tableHeader.setSize(tableHeader.getPreferredSize()); jTable2.print(JTable.PrintMode.FIT_WIDTH); } catch (PrinterException ex) { ex.printStackTrace(); } }