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我是 Java 新手，无法让我的小程序运行。由于某种原因，无法实例化该类。我尝试了一些东西，但没有任何帮助，我真的被卡住了。

这是我收到的错误。

load: com.yunatech.pns.chequeprint.HTMLPrinter.class can't be instantiated.
java.lang.InstantiationException: com.yunatech.pns.chequeprint.HTMLPrinter
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

这是我的代码。

package com.yunatech.pns.chequeprint;

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.print.Book;
import java.awt.print.PageFormat;
import java.awt.print.Paper;
import java.awt.print.Printable;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import java.io.IOException;

import javax.swing.JEditorPane;
import javax.swing.JFrame;

public class HTMLPrinter extends Applet implements Printable{
    /**
     * 
     */
    private static final long serialVersionUID = 2343838467856002371L;
    private final JEditorPane printPane;

    public HTMLPrinter(JEditorPane editorPane){
        printPane = editorPane;
    }

    public int print(Graphics graphics, PageFormat pageFormat, int pageIndex){
        if (pageIndex >= 1) return Printable.NO_SUCH_PAGE;

        Graphics2D g2d = (Graphics2D)graphics;
        g2d.translate((int)pageFormat.getImageableX(), (int)pageFormat.getImageableY());

        printPane.setSize((int)pageFormat.getImageableWidth(), (int)pageFormat.getImageableHeight());
        printPane.print(g2d);

        return Printable.PAGE_EXISTS;
    }

    protected static String dump(Paper paper) {
        StringBuilder sb = new StringBuilder(64);
        sb.append(paper.getWidth()).append("x").append(paper.getHeight())
                .append("/").append(paper.getImageableX()).append("x").
                append(paper.getImageableY()).append(" - ").append(paper
                .getImageableWidth()).append("x").append(paper.getImageableHeight());
        return sb.toString();
    }

    protected static String dump(PageFormat pf) {
        Paper paper = pf.getPaper();
        return dump(paper);
    }

    public void main(String[] args){

        final JFrame frame = new JFrame("Letter wrap test"); 
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

        final JEditorPane htmlTextPane = new JEditorPane(); 

        String paramUrl   = getParameter("paramUrl");

        htmlTextPane.setContentType("text/html");
        try {
            htmlTextPane.setPage(paramUrl);
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        HTMLPrinter target = new HTMLPrinter(htmlTextPane);

        PrinterJob pj = PrinterJob.getPrinterJob();
        if (pj.printDialog()) {
            PageFormat pf = pj.defaultPage();
            Paper paper = pf.getPaper();
            double width = 8d * 72d;
            double height = 4d * 72d;
            double margin = 0.1d * 72d;
            paper.setSize(width, height);
            paper.setImageableArea(
                    margin,
                    0,
                    width - (margin * 2),
                    height);
            System.out.println("Before- " + dump(paper));
            pf.setOrientation(PageFormat.PORTRAIT);
            pf.setPaper(paper);
            System.out.println("After- " + dump(paper));
            System.out.println("After- " + dump(pf));
            dump(pf);
            PageFormat validatePage = pj.validatePage(pf);
            System.out.println("Valid- " + dump(validatePage));

            Book pBook = new Book();
            pBook.append(target, pf);
            pj.setPageable(pBook);

            try {
                pj.print();
            } catch (PrinterException ex) {
                ex.printStackTrace();
            }
        }

    } //main

}

如果有人能帮助我指出正确的方向，我将不胜感激。

谢谢。

4

1 回答 1

1

这是您要声明的唯一构造函数：

public HTMLPrinter(JEditorPane editorPane){
    printPane = editorPane;
}

我相信小程序运行器基础设施需要一个公共的无参数构造函数。您希望它从哪里获得JEditorPane传递给您的构造函数？

请注意，您的main方法在这里无关紧要 - 这不是小程序的启动方式。

于 2012-11-27T13:18:27.003 回答