Struct Util 权威指南 - 配置文件的热重载

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public FileWatcherService register(String dir) throws IOException {
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    return this.register(Paths.get(Objects.requireNonNull(dir, "dir")));
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}
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public FileWatcherService register(Path dir) throws IOException {
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    Objects.requireNonNull(dir, "dir");
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    WatchKey key = dir.register(ws, StandardWatchEventKinds.ENTRY_MODIFY);
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    Path p = keys.putIfAbsent(key, dir);
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    if (null == p) {
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        LOGGER.info("Register file watcher service. path: {}", dir.toAbsolutePath());
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    }
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    return this;
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}
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public FileWatcherService registerAll(String path) throws IOException {
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    return this.registerAll(Paths.get(path));
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}
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/**
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    * Register the given directory, and all its sub-directories, with the
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    * WatchService.
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    */
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public FileWatcherService registerAll(final Path start) throws IOException {
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    Objects.requireNonNull(start, "start");
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    // register directory and sub-directories
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    Files.walkFileTree(start, new SimpleFileVisitor<>() {
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        @Override
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        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
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            register(dir);
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            return FileVisitResult.CONTINUE;
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        }
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    });
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    return this;
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}

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/**
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* Schedule process the file watch events.
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*/
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private void process() {
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    try {
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        WatchKey key;
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        Path dir;
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        if ((key = ws.poll()) == null
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                || (dir = keys.get(key)) == null) {
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            LOGGER.debug("watch key not registered. key:{}", key);
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            return;
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        }
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        for (WatchEvent<?> event : key.pollEvents()) {
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            WatchEvent.Kind<?> kind = event.kind();
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            if (kind == StandardWatchEventKinds.OVERFLOW) {
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                continue;
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            }
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            WatchEvent<Path> ev = (WatchEvent<Path>) event;
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            Path name = ev.context();
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            Path child = dir.resolve(name);
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            List<Runnable> l = hooksMap.get(child);
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            if (l != null) {
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                try {
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                    l.forEach(Runnable::run);
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                } catch (Exception e) {
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                    LOGGER.error("process data file failure. file:{}", child.toAbsolutePath(), e);
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                    throw e;
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                }
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            }
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        }
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        boolean valid = key.reset();
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        if (!valid) {
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            this.keys.remove(key);
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        }
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    } catch (Throwable e) {
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        LOGGER.error("file watcher service throw an unknown exception.", e);
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    }
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}