从JAR而不是Eclipse运行时，从Java应用程序打开tmp PDF时出错

Question

我希望能够打开一个PDF文件时，用户点击'帮助'在我的应用程序。PDF文件位于JAR中，解压缩到tmp目录，然后通过awt.Desktop.getDesktop()选择打开(允许windows和linux使用)。

当我从Eclipse中运行应用程序时，它工作正常，PDF打开时没有错误。当我导出到JAR并运行时，我会得到一个错误，说明"PDF文档损坏"，如果我手动导航到PDF文档(在我的ubuntu机器/tmp/546434564.pdf)，那么当我试图打开文件时，我会得到同样的错误。我不明白发生了什么事。"损坏"的PDF文件大小与正常的PDF相同，所以我认为这不是权限问题。

我使用的代码是:

public Main() throws FontFormatException, IOException {
    //lets load the font
       Font font = Font.createFont(Font.TRUETYPE_FONT, this.getClass().getResourceAsStream("/Coalition_v2.ttf")).deriveFont(Font.PLAIN, 14); 
       System.out.println(font);
    //lets write the tmp file for help to the machine now
       try {
            java.io.InputStream iss = getClass().getResourceAsStream("/nullpdf.pdf"); //update the filename here when the help guide is written
            byte[] data = new byte[iss.available()];
            iss.read(data);
            iss.close();
            String tempFile = "file";
            File temp = File.createTempFile(tempFile, ".pdf");
            FileOutputStream fos = new FileOutputStream(temp);
            fos.write(data);
            fos.flush();
            fos.close();
        tmphelpfile = temp.getAbsolutePath();
        System.out.println(tmphelpfile);
        } catch (IOException ex) {
            ex.printStackTrace();
            System.out.println("TEMP FILE NOT CREATED - ERROR in tmp file writing");
        }

然后调用pdf:

JMenu mnHelpGuide = new JMenu("Help Guide");
mnHelpGuide.addMouseListener(new MouseAdapter() {
    @Override
    public void mouseClicked(MouseEvent e) {
    //  Help();
        Desktop d = java.awt.Desktop.getDesktop ();  
        try {
            System.out.println(tmphelpfile);
            d.open (new java.io.File (String.valueOf(tmphelpfile)));
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            System.out.println("Couldnt open your file - error on HELP Guide");
            e1.printStackTrace();
        } 
    }
    });

Answer 1

谢谢大家的帮助。通过导入apachecommago jar，然后将代码修改为:

，可以解决这个问题:

 try {
                java.io.InputStream iss = getClass().getResourceAsStream("/nullpdf.pdf"); //update the filename here when the help guide is written
               // byte[] data = new byte[iss.available()];
                byte[] data = IOUtils.toByteArray(iss);
                iss.read(data);
                iss.close();
                String tempFile = "file";
                File temp = File.createTempFile(tempFile, ".pdf");
                FileOutputStream fos = new FileOutputStream(temp);
                fos.write(data);
                fos.flush();
                fos.close();
            tmphelpfile = temp.getAbsolutePath();
            System.out.println(tmphelpfile);
            } catch (IOException ex) {
                ex.printStackTrace();
                System.out.println("TEMP FILE NOT CREATED - ERROR in tmp file writing");
            }