Java Path File Content fileContent(final Path p)

Description

Read a file content, or wait the file to be created.

License

Open Source License

Parameter

Parameter	Description
p	the file path

Exception

Parameter	Description
IOException	an exception
InterruptedException	an exception

Return

the content

Declaration

@SuppressWarnings("unchecked")
public static String fileContent(final Path p) throws IOException, InterruptedException 

Method Source Code

//package com.java2s;
/*/*from   w  w w.ja  v a2  s.c  om*/
 * Copyright (C) 2013 Fabien Vauchelles (fabien_AT_vauchelles_DOT_com).
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3, 29 June 2007, of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301  USA
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;

public class Main {
    /**
     * Read a file content, or wait the file to be created. Delete the file after read.
     *
     * @param p the file path
     * @return the content
     * @throws IOException
     * @throws InterruptedException
     */
    @SuppressWarnings("unchecked")
    public static String fileContent(final Path p) throws IOException, InterruptedException {
        if (p == null) {
            throw new IllegalArgumentException();
        }

        if (Files.exists(p)) {
            return readAndDelete(p);
        }

        final Path parent = p.getParent();
        if (Files.notExists(parent)) {
            Files.createDirectory(parent);
        } else {
            if (!Files.isDirectory(parent)) {
                throw new IllegalArgumentException(parent + " exists but is not a directory");
            }
        }

        try (final WatchService watcher = FileSystems.getDefault().newWatchService()) {
            parent.register(watcher, StandardWatchEventKinds.ENTRY_CREATE);

            while (true) {
                final WatchKey key = watcher.take();

                for (final WatchEvent<?> event : key.pollEvents()) {
                    final WatchEvent.Kind<?> kind = event.kind();

                    if (kind == StandardWatchEventKinds.ENTRY_CREATE) {
                        final WatchEvent<Path> ev = (WatchEvent<Path>) event;
                        final Path p2 = parent.resolve(ev.context());
                        if (p.equals(p2)) {
                            return readAndDelete(p);
                        }
                    }
                }
            }
        }
    }

    /**
     * Read and delete file and return the content.
     *
     * @param p the file path
     * @return the content
     * @throws IOException
     */
    public static String readAndDelete(final Path p) throws IOException {
        final StringBuilder sb = new StringBuilder();

        try (BufferedReader bfr = Files.newBufferedReader(p, Charset.forName("UTF-8"))) {
            String line = bfr.readLine();
            while (line != null) {
                sb.append(line);

                line = bfr.readLine();
            }
        }

        Files.delete(p);

        return sb.toString();
    }
}

Related

1. appendToLog(String content, Path newFile)
2. assertSameContent(String expectedFilePath, String actualFilePath)
3. contentEquals(Path leftPath, Path rightPath)
4. fileContent(final String filePath)
5. getContent(Path path)
6. getFileContents(final String absFilePath)
7. getFileContents(Path file)