java - 文件正在被另一个进程使用，但 canRead() 返回 true

Question

我正在使用另一个程序将 bin 文件转换为 xml，然后尝试读取该文件。使用以下代码:

File file = new File(currentPath + "/ammunition.bin");
File file2 = fileTools.convert(file);
ArrayList<String> asd = fileTools.readFile(file2);

我收到 FileNotFoundException，“文件正在被另一个进程使用”。奇怪的是 file.canRead() 返回 true，即使我收到异常。这是其余的代码:

public ArrayList<String> readFile(File file) {

    ArrayList<String> result = new ArrayList<>();
    Scanner reader;
    try {
        reader = new Scanner(file, "UTF-8");
    } catch (FileNotFoundException ex) {
        boolean b = file.canRead();
        StringWriter errors = new StringWriter();
        ex.printStackTrace(new PrintWriter(errors));
        JOptionPane.showMessageDialog(null, errors.toString());
        alertError("readFile\n" + b + " " + ex.getMessage());
        return null;
    }
    while (reader.hasNext()) {
        result.add(reader.nextLine());
    }
    reader.close();
    return result;
}

public File changeFileExtension(File f, String ext) {
    String name = f.getAbsolutePath();
    int i = name.lastIndexOf(".");
    name = name.substring(0, i) + "." + ext;
    f = new File(name);
    return f;
}


public File convert(File file) {

    File binConverter = new File(this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe");

    if (!binConverter.exists()) {
        alertError("convert\nGibbedsTools is missing, it should be in\n" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe");
        return null;
    }

    if (!file.exists()) {
        alertError("convert\nFile does not exist\n" + file.getAbsolutePath());
    }

    String name = file.getName();
    String extension = name.substring(name.lastIndexOf(".") + 1, name.length());

    Runtime rt = Runtime.getRuntime();

    try {
        rt.exec("cmd.exe /c " + "\"\"" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe\" \"" + file.getAbsolutePath() + "\"\"");
    } catch (IOException ex) {
        alertError("binToXml\n" + ex.getMessage());
        return null;
    }

    File file2 = changeFileExtension(file, extension.equals("xml") ? "bin" : "xml");

    int timepassed = 0;

    while (!file2.exists() || !file2.canWrite() || timepassed <= 50) {
        try {
            Thread.sleep(50);
        } catch (InterruptedException ex) {
            alertError("binToXml\n" + ex.getMessage());
            return null;
        }
        timepassed += 50;
        if (timepassed > 3000) {
            if (!file2.exists()) {
                alertError("convert\nError, binconverter probably crashed (No xml file created after 3 seconds from passing file to binconverter)\n"
                        + "xml file should be in:\n"
                        + file2.getAbsolutePath() + "     Found: " + file2.exists());
                return null;
            }
        }
        if (timepassed > 6000 && !file2.canWrite()) {
            alertError("convert\nCan't write to the xml file after 6 seconds from passing the file to binconverter."
                    + file2.getAbsolutePath() + "     Can write: " + file2.canWrite());
            return null;
        }
    }

    return file2;
}

Answer 1

而不是:

Runtime rt = Runtime.getRuntime();
.
.
.

试试这个:

 Process p = Runtime.getRuntime().exec("cmd.exe /c " + "\"\"" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe\" \"" + file.getAbsolutePath() + "\"\"");

然后您可以使用以下命令等待它完成:

p.waitFor();

一旦外部程序完成，就会释放该文件。更好的解决方案是使用 Processbuilder

您还可以使用以下方式销毁进程

p.destroy();

当然尽量避免使用它。除非程序很难处理。