Java 加载 PDF 文件文件不存在

Question

我试图让我的 Java 应用程序在用户单击按钮时打开一个 PDF 文件。但是，我得到下面的堆栈跟踪，指出该文件不存在。基本上，我希望能够在用户进行选择时加载此文件。

下面是堆栈跟踪，然后是代码和路径的屏幕截图。

堆栈跟踪：

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: The file: \RFBase-TD_Communications\src\pdf\RFTDAnalyzerHelpFile.pdf doesn't exist.
    at java.awt.Desktop.checkFileValidation(Unknown Source)
    at java.awt.Desktop.open(Unknown Source)
    at GUI.rfbgui.openPDF(rfbgui.java:787)
    at GUI.rfbgui.access$7(rfbgui.java:773)
    at GUI.rfbgui$6.actionPerformed(rfbgui.java:921)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.AbstractButton.doClick(Unknown Source)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

代码：

private static void openPDF()
{
    File pdfHelpFile = new File("/RFBase-TD_Communications/src/pdf/RFTDAnalyzerHelpFile.pdf");
    try
    {
        Desktop.getDesktop().open(pdfHelpFile);

    }catch(IOException ex)
    {
        ex.printStackTrace();
    }
}

Answer 1

对于如何处理这些情况，我有一些一般性建议。文件是我开始学习编程时非常沮丧的事情之一。

1. 使用 System.getProperty("user.dir"); 这会非常有用，尤其是当您不知道程序将从哪里运行时，或者您有一个具体的文件结构。

2. 在 Java 中，我一般建议使用“\”而不是“/”。

3. 对您尝试加载的文件运行完整性检查。专门检查它是否为空，.isFile() 等。你永远不知道你可能会得到什么，所以最好在意外崩溃之前达到峰值。

这里有一些类似问题的链接，可能会对您有所帮助；

How should I load files into my Java application?

Getting the Current Working Directory in Java

Getting the inputstream from a classpath resource (XML file)

Answer 2

File myFile = new File(getClass().getResource("/files/test.pdf").toURI());

或

if (Desktop.isDesktopSupported()) {
try {
    File myFile = new File("/path/to/file.pdf");
    Desktop.getDesktop().open(myFile);
} catch (IOException ex) {
    // no application registered for PDFs
}