【小家java】java7新特性（简述八大新特性） 不温不火（下）

public class ThreadPoolManager {
    private final ScheduledExecutorService stpe = Executors
            .newScheduledThreadPool(2);
    private final BlockingQueue<WorkUnit<String>> lbq;
    public ThreadPoolManager(BlockingQueue<WorkUnit<String>> lbq_) {
        lbq = lbq_;
    }
    public ScheduledFuture<?> run(QueueReaderTask msgReader) {
        msgReader.setQueue(lbq);
        return stpe.scheduleAtFixedRate(msgReader, 10, 10, TimeUnit.MILLISECONDS);
    }
    private void cancel(final ScheduledFuture<?> hndl) {
        stpe.schedule(new Runnable() {
            public void run() {
                hndl.cancel(true);
            }
        }, 10, TimeUnit.MILLISECONDS);
    }
    /**
     * 使用传统的反射api
     */
    public Method makeReflective() {
        Method meth = null;
        try {
            Class<?>[] argTypes = new Class[]{ScheduledFuture.class};
            meth = ThreadPoolManager.class.getDeclaredMethod("cancel", argTypes);
            meth.setAccessible(true);
        } catch (IllegalArgumentException | NoSuchMethodException
                | SecurityException e) {
            e.printStackTrace();
        }
        return meth;
    }
    /**
     * 使用代理类
     * @return
     */
    public CancelProxy makeProxy() {
        return new CancelProxy();
    }
    /**
     * 使用Java7的新api，MethodHandle
     * invoke virtual 动态绑定后调用 obj.xxx
     * invoke special 静态绑定后调用 super.xxx
     * @return
     */
    public MethodHandle makeMh() {
        MethodHandle mh;
        MethodType desc = MethodType.methodType(void.class, ScheduledFuture.class);
        try {
            mh = MethodHandles.lookup().findVirtual(ThreadPoolManager.class,
                    "cancel", desc);
        } catch (NoSuchMethodException | IllegalAccessException e) {
            throw (AssertionError) new AssertionError().initCause(e);
        }
        return mh;
    }
    public static class CancelProxy {
        private CancelProxy() {
        }
        public void invoke(ThreadPoolManager mae_, ScheduledFuture<?> hndl_) {
            mae_.cancel(hndl_);
        }
    }
}

public class ThreadPoolMain {
    /**
     * 如果被继承，还能在静态上下文寻找正确的class
     */
    private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
    private ThreadPoolManager manager;
    public static void main(String[] args) {
        ThreadPoolMain main = new ThreadPoolMain();
        main.run();
    }
    private void cancelUsingReflection(ScheduledFuture<?> hndl) {
        Method meth = manager.makeReflective();
        try {
            System.out.println("With Reflection");
            meth.invoke(hndl);
        } catch (IllegalAccessException | IllegalArgumentException
                | InvocationTargetException e) {
            e.printStackTrace();
        }
    }
    private void cancelUsingProxy(ScheduledFuture<?> hndl) {
        CancelProxy proxy = manager.makeProxy();
        System.out.println("With Proxy");
        proxy.invoke(manager, hndl);
    }
    private void cancelUsingMH(ScheduledFuture<?> hndl) {
        MethodHandle mh = manager.makeMh();
        try {
            System.out.println("With Method Handle");
            mh.invokeExact(manager, hndl);
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }
    private void run() {
        BlockingQueue<WorkUnit<String>> lbq = new LinkedBlockingQueue<>();
        manager = new ThreadPoolManager(lbq);
        final QueueReaderTask msgReader = new QueueReaderTask(100) {
            @Override
            public void doAction(String msg_) {
                if (msg_ != null)
                    System.out.println("Msg recvd: " + msg_);
            }
        };
        ScheduledFuture<?> hndl = manager.run(msgReader);
        cancelUsingMH(hndl);
        // cancelUsingProxy(hndl);
        // cancelUsingReflection(hndl);
    }
}

public class PathUsage {
    public void usePath() {
        Path path1 = Paths.get("folder1", "sub1");
        Path path2 = Paths.get("folder2", "sub2");
        path1.resolve(path2); //folder1\sub1\folder2\sub2
        path1.resolveSibling(path2); //folder1\folder2\sub2
        path1.relativize(path2); //..\..\folder2\sub2
        path1.subpath(0, 1); //folder1
        path1.startsWith(path2); //false
        path1.endsWith(path2); //false
        Paths.get("folder1/./../folder2/my.text").normalize(); //folder2\my.text
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        PathUsage usage = new PathUsage();
        usage.usePath();
    }
}

public class ListFile {
    public void listFiles() throws IOException {
        Path path = Paths.get("");
        try (DirectoryStream<Path> stream = Files.newDirectoryStream(path, "*.*")) {
            for (Path entry: stream) {
                //使用entry
                System.out.println(entry);
            }
        }
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        ListFile listFile = new ListFile();
        listFile.listFiles();
    }
}

public class FilesUtils {
    public void manipulateFiles() throws IOException {
        Path newFile = Files.createFile(Paths.get("new.txt").toAbsolutePath());
        List<String> content = new ArrayList<String>();
        content.add("Hello");
        content.add("World");
        Files.write(newFile, content, Charset.forName("UTF-8"));
        Files.size(newFile);
        byte[] bytes = Files.readAllBytes(newFile);
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        Files.copy(newFile, output);
        Files.delete(newFile);
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        FilesUtils fu = new FilesUtils();
        fu.manipulateFiles();
    }
}

public class WatchAndCalculate {
    public void calculate() throws IOException, InterruptedException {
        WatchService service = FileSystems.getDefault().newWatchService();
        Path path = Paths.get("").toAbsolutePath();
        path.register(service, StandardWatchEventKinds.ENTRY_CREATE);
        while (true) {
            WatchKey key = service.take();
            for (WatchEvent<?> event : key.pollEvents()) {
                Path createdPath = (Path) event.context();
                createdPath = path.resolve(createdPath);
                long size = Files.size(createdPath);
                System.out.println(createdPath + " ==> " + size);
            }
            key.reset();
        }
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws Throwable {
        WatchAndCalculate wc = new WatchAndCalculate();
        wc.calculate();
    }
}