Question

我有以下代码：

 public void searchStringInFile(String directory, String word)
    {
        if (word != null && directory != null)
        {

            File filePath = new File(directory);
            Queue<File> queue = new LinkedList<>();
            queue.add(filePath);

            while (!queue.isEmpty())
            {
                File currentFile = queue.poll();
                File[] listOfDirectories = currentFile.listFiles();

                if (listOfDirectories != null)
                {
                    for (File file : listOfDirectories)
                    {
                        if (file.isDirectory())
                        {
                            queue.add(file);
                        }
                        else
                        {
                            Thread thread = new Thread(new Runnable()
                            {

                                @Override
                                public void run()
                                {
                                    readText(file, word);

                                }
                            });
                            thread.start();
                        }
                    }
                }
            }

        }
    }


    private void readText(File file, String word)
    {
        Scanner scan = null;
        try
        {

            scan = new Scanner(file);
            String line;
            int lineNumber = 0;
            while (scan.hasNextLine())
            {
                line = scan.nextLine();
                lineNumber++;
                if (line.contains(word))
                {
                    System.out.println("Line: " + lineNumber + " contains the word: " + word + "  at file: " + file.getAbsolutePath());
                }
            }

        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
        finally
        {
            close(scan);
        }

它正在目录和子目录中的所有文件中找到String(word)。我想使其成为多线程应用程序-当它进入目录（或找到目录）时，它必须启动new Thread并开始在文件中搜索，而我实际上并不知道该怎么做。我就像上面的代码一样，每次打开文件时都启动new Thread，但是必须在进入目录时启动它。

Answer 1

如果我正确理解了您的问题，并且想在循环后启动线程，则可以这样操作：

 public void searchStringInFile(String directory, String word){
    if (word == null || directory == null) {
        return;
    }

    File filePath = new File(directory);
    Queue<File> queue = new ConcurrentLinkedQueue<>();
    queue.add(filePath);

    while (!queue.isEmpty()) {
        File currentFile = queue.poll();
        File[] listOfDirectories = currentFile.listFiles();

        if (listOfDirectories != null)
        {
            new Thread(() -> {
                for (File file : listOfDirectories)
                {
                    if (file.isDirectory()) {
                        queue.add(file);
                    } else {
                       readText(file, word);
                    }
                }
            }).start();

        }
    }
}

您需要将队列更改为ConcurrentLinkedQueue，这是线程安全的实现，因为现在您有多个线程同时更改Queue。

每次在目录Java中搜索时如何创建新线程

1 个答案: