java - 将 JPanel 发送到打印机

Question

是否可以只将 JPanel 或任何其他组件发送到打印机？还是我必须手动实现对图形对象的所有绘图？

我尝试使用 JPanel 的 Print* 函数打印到图形对象，但打印的页面是空白的。

Answer 1

查看 Java 打印 API and tutorial连同 JComponent.print(Graphics)。

这是一个基本的类，它将打印适合 1 页的任何组件(我不能相信这一点，我从 Marty Hall's tutorial 获得了代码):

import java.awt.*;
import java.awt.print.*;
import javax.swing.*;

/**
 * Generic component printer.  This object allows any AWT or Swing component  (or DCT system)
 * to be printed by performing it pre and post print responsibilities.
 * <p>
 * When printing components, the role of the print method is nothing more than to scale the Graphics, turn off double
 * buffering, and call paint.  There is no particular reason to put that print method in the component being printed.  A
 * better approach is to build a generic printComponent method to which you simply pass the component you want printed.
 * <p>
 * With Swing, almost all components have double buffering turned on by default. In general, this is a great benefit,
 * making for convenient and efficient painting. However, in the specific case of printing, it can is a huge problem.
 * First, since printing components relies on scaling the coordinate system and then simply calling the component's
 * paint method, if double buffering is enabled printing amounts to little more than scaling up the buffer (off-screen
 * image) which results in ugly low-resolution printing like you already had available. Secondly, sending these huge
 * buffers to the printer results in huge print spooler files which take a very long time to print. Consequently this
 * object globally turns off double buffering before printing and turns it back on afterwards.
 * <p>
 * Threading Design : [x] Single Threaded  [ ] Threadsafe  [ ] Immutable  [ ] Isolated
 */

public class ComponentPrinter
extends Object
implements Printable
{

// *****************************************************************************
// INSTANCE PROPERTIES
// *****************************************************************************

private Component                       component;                              // the component to print

// *****************************************************************************
// INSTANCE CREATE/DELETE
// *****************************************************************************

public ComponentPrinter(Component com) {
    component=com;
    }

// *****************************************************************************
// INSTANCE METHODS
// *****************************************************************************

public void print() throws PrinterException {
    PrinterJob                          printJob=PrinterJob.getPrinterJob();

    printJob.setPrintable(this);
    if(printJob.printDialog()) {
        printJob.print();
        }
    }

public int print(Graphics gc, PageFormat pageFormat, int pageIndex) {
    if(pageIndex>0) {
        return NO_SUCH_PAGE;
        }

    RepaintManager                      mgr=RepaintManager.currentManager(component);
    Graphics2D                          g2d=(Graphics2D)gc;

    g2d.translate(pageFormat.getImageableX(),pageFormat.getImageableY());
    mgr.setDoubleBufferingEnabled(false);                                       // only for swing components
    component.paint(g2d);
    mgr.setDoubleBufferingEnabled(true);                                        // only for swing components
    return PAGE_EXISTS;
    }

// *****************************************************************************
// STATIC METHODS
// *****************************************************************************

static public void printComponent(Component com) throws PrinterException {
    new ComponentPrinter(com).print();
    }

} // END PUBLIC CLASS