File deletion/moving failing

问题

In the code below I am trying to select xml files from an ArrayList xmls where xmls.get(i) is the absolute path of a file with extension .xml. If this file cannot be parsed by Document an exception is thrown and the file is moved to a different directory. However, I cannot move or delete the file although I can copy it to the directory destFile. The values of the last if statement return true for f.exists(), f.canRead(), f.canWrite(), f.canExecute but returns false forf.renameTo(destFile);

for(int i=0; i<xmls.size(); i++){
    boolean delete = false;

    try {
        File f = new File(xmls.get(i));
        File destFile = new File(structDir + "/badXMLs/" + f.getName());

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document doc = db.parse(f);
        doc.getDoctype();

    } catch (Exception e) {
        File f = new File(xmls.get(i));
        File destFile = new File(structDir + "/badXMLs/" + f.getName());

        System.out.println(f.getName());
        delete = true;
    } 

    if(delete){
        File f = new File(xmls.get(i));
        File destFile = new File(structDir + "/badXMLs/" + f.getName());

        System.out.println(f.exists());
        System.out.println(f.canRead());
        System.out.println(f.canWrite());
        System.out.println(f.canExecute());

        System.out.println(f.renameTo(destFile));
    }
}

回答1:

The default DocumentBuilder does not close the file when you get an Exception. The easiest way to avoid this is to use a FileInputStream, and close it yourself, like:

FileInputStream fis = null;

try {
    File f = new File(xmls.get(i));
    File destFile = new File(structDir + "/badXMLs/" + f.getName());
    fis = new FileInputStream(f);

    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = dbf.newDocumentBuilder();
    Document doc = db.parse(fis); // parse the FileInputStream, not the File
    doc.getDoctype();

} catch (Exception e) {
    if (fis != null) {
        fis.close();
    }

    File f = new File(xmls.get(i));
    File destFile = new File(structDir + "/badXMLs/" + f.getName());

    System.out.println(f.getName());
    delete = true;
} 

It doesn't close it, so under windows at least, you can't delete it or rename it. Note that you don't need to create the DocumentBuilder each time either.

回答2:

Not sure about the answers that suggest you call close() on a file object since java.io.File has no such method, but I think they're headed in the right direction.

I'd suggest switching to using a FileInputStream and closing it.

the parse method can take either a File object or a FileInputStream so that should be ok.

来源：https://stackoverflow.com/questions/8714893/file-deletion-moving-failing