尝试将文件创建到（可能）正确的目录时出现 java.io.FileNotFoundException

Question

您好，我的问题是当我使用这个时：

final File f = newFile(ButtonOneEvent.class.getProtectionDomain().getCodeSource().getLocation().getPath());
filePath = f.toString() + "/PlayerList.txt"; //Playerlist.txt being the file I want to create, filePath being an empty string.
System.out.println(f);

为此定义类的本地目录：

FileOutputStream fout = new FileOutputStream(Start.filePath); //**Reference Point**
if(inputData != null) {     //Ignore the if else statement
    new PrintStream(fout).println("Text Stuff")
} else {
    new PrintStream(fout).println("Text Stuff")
}
fout.close();

当我想创建这个文件时，我在“参考点”行上得到一个java.io.FileNotFoundException，当然它还没有。 此代码由JButton 激活。
顺便说一句，Sytem.out.println(f) 输出如下：

*/Users/HillFamily/Library/Application%20Support/Youth%20Digital/Software/Forge/mcp/eclipse/Football%20Card%20Sorter/bin* <- Directory

StackTrace：（抱歉，拖了这么久！）

java.io.FileNotFoundException: /Users/HillFamily/Library/Application%20Support/Youth%20Digital/Software/Forge/mcp/eclipse/Football%20Card%20Sorter/bin/PlayerList.txt (No such file or directory)
    at java.io.FileOutputStream.open(Native Method)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:194)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:84)
    at events.ButtonOneEvent.actionPerformed(ButtonOneEvent.java:33)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6414)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3275)
    at java.awt.Component.processEvent(Component.java:6179)
    at java.awt.Container.processEvent(Container.java:2084)
    at java.awt.Component.dispatchEventImpl(Component.java:4776)
    at java.awt.Container.dispatchEventImpl(Container.java:2142)
    at java.awt.Component.dispatchEvent(Component.java:4604)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4618)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4279)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4209)
    at java.awt.Container.dispatchEventImpl(Container.java:2128)
    at java.awt.Window.dispatchEventImpl(Window.java:2492)
    at java.awt.Component.dispatchEvent(Component.java:4604)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:717)
    at java.awt.EventQueue.access$400(EventQueue.java:82)
    at java.awt.EventQueue$2.run(EventQueue.java:676)
    at java.awt.EventQueue$2.run(EventQueue.java:674)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:690)
    at java.awt.EventQueue$3.run(EventQueue.java:688)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:687)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Answer 1

首先：看看这个方法'newFile'，也许你必须更改为正确的文件调用：

文件 f = new File(mypath+"PlayerList.txt");

其次，试试看你的类成员'filePath'是否没有被改变（Start类的成员）。

Answer 2

如果您想创建一个 OutputStream 以写入文件，请使用：
如果文件不存在，这也会创建文件。

try {
        Path p = Paths.get("demo", "test.txt");
        Files.createDirectories(p.getParent());
        DataOutputStream out = new DataOutputStream(Files.newOutputStream(p, StandardOpenOption.CREATE, StandardOpenOption.WRITE));
        out.writeBytes("Hello-World!!");
        out.flush();
        out.close();            
    } catch (IOException ex) {
        Logger.getLogger(NewJFrame.class.getName()).log(Level.SEVERE, null, ex);
    }

Answer 3

很可能是因为您的Start.filePath 是目录（不是文件）、无法创建或根本不存在。此外，Start.filePath 依赖于系统，并且必须与您的平台兼容。您需要确保这是正确的，并且您所指的位置有足够的访问权限进行写操作。另一个问题，您的完整路径名如何知道您正在查看/写入正确的位置？路径上的某些目录是否真的存在？

从修复操作开始 - 您可能需要检查您的 System.out.println(Start.filePath) 是否打印了任何有意义的内容。如果您遇到空格和 URL 编码问题（例如 %20 是 ASCII 中的空格），您需要开始在您的问题上下文中考虑它们。

作为示例（从 Windows 的角度来看），请参见以下内容：

    public static void main(String[] args) {
        try{

         FileOutputStream fos = new FileOutputStream("C:/myjavaprojects/folder%20with%20a%20space/haha.txt");
         // This is unchecked exception - we have to rethrow/catchprocess it
         BufferedOutputStream bos = new BufferedOutputStream(fos);

         bos.write("Writing to file".getBytes());        
         bos.flush();
         bos.close();
        } catch (FileNotFoundException fnfe){

            try{
                FileOutputStream fos = new FileOutputStream("C:/myjavaprojects/folder with a space/haha.txt");
                 BufferedOutputStream bos = new BufferedOutputStream(fos);
                 bos.write("Writing to file".getBytes());            
                 bos.flush();
                 bos.close();
            } catch(FileNotFoundException e){
                e.printStackTrace();
            } catch (IOException ioe){
                ioe.printStackTrace();
            }

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

    }
}