使用 Java 建立 Windows 中的文件索引 10

Question

I am writing a desktop application in Java to quickly find files. I have used the exec command in Java to run powershell to do this, as Java's os.walk method seems to be much slower. Right now it takes about 5 minutes to generate a text file that lists the contents of all files on my computer (a total of around 440,000 files).

This is fine, but the problem I have is that I have no way of updating this list of files. So if I change a few files in my file system and want to update my file list, I can't do so quickly (ie incrementally). Instead, I have to generate the file list all over from scratch.

I know you can use git-bash to create a locate database (using updatedb). Now this is an awesome solution, but the application I'm trying to create may be used by people who don't have that installed. So I'd like to do it using default apps provided with Windows (ie powershell, or natively in Java). I am trying to make this app easy to use, so I don't want the user to have to install a bunch of other dependencies.

Answer 1

The following code shows how to use Java and avoid Powershell altogether. It builds an array in memory and writes it to a text file (467,000 files listed) all in under 30 seconds!

Run the following code in Main or wherever you want. It calls the createFileList method.

List<Path> pathsArrayList = new ArrayList<>();
Path rootPath_obj;
rootPath_obj = Paths.get(this.configMap.get("root_path"));
createFileList(rootPath_obj);

Here's the tree stream traversal code:

public void createFileList(Path path_in) throws IOException, AccessDeniedException {

    try (DirectoryStream<Path> mystream = Files.newDirectoryStream(path_in)) {

        for (Path entry : mystream) {
            if (Files.isDirectory(entry)) {
                createFileList(entry);
            }
            pathsArrayList.add(entry);
        }
    }
    catch (AccessDeniedException ex) {
        // Do nothing, just move on to the next file
    }
}

Now write the file to save for later. This is the listing of all files within the root path tree.

    System.out.println("Writing database...");
    try (FileWriter writer = new FileWriter(this.configMap.get("db_path"))) {
        for(Path pth: pathsArrayList){
            writer.write(pth.toString() + System.lineSeparator());
        }
    }
    System.out.println("...database written.");