Executor任务执行框架的应用

public interface Executor {

    /**
     * Executes the given command at some time in the future.  The command
     * may execute in a new thread, in a pooled thread, or in the calling
     * thread, at the discretion of the <tt>Executor</tt> implementation.
     *
     * @param command the runnable task
     * @throws RejectedExecutionException if this task cannot be
     * accepted for execution.
     * @throws NullPointerException if command is null
     */
    void execute(Runnable command);
}

   // 定义一个页面导航的队列
final BlockingQueue<String> naviQueue = new LinkedBlockingQueue<String>(3);
// 定义一个图片网址的队列
final BlockingQueue<String> imgQueue = new LinkedBlockingQueue<String>(100);

final int DOWNLOAD_THREAD = 30;
final int PAGE_THREAD = 2;
final ExecutorService exec = Executors.newFixedThreadPool((DOWNLOAD_THREAD + PAGE_THREAD));

// 定义一个开始的倒数锁
final CountDownLatch begin = new CountDownLatch(1);
// 定义一个结束的倒数锁
final CountDownLatch end = new CountDownLatch((DOWNLOAD_THREAD + PAGE_THREAD));

public ThreadPoolMananger() {
	int i = 1;
	for (; i <= PAGE_THREAD; i++) {
		exec.submit(new PageThread(i, begin, end));
	}
	for (; i <= (DOWNLOAD_THREAD + PAGE_THREAD); i++) {
		exec.submit(new ImageThread(i, "D:\\pictures", begin, end));
	}
	HtmlParser parser = new HtmlParser();
	SimpleHttpClient client = new SimpleHttpClient();
	parser.setHtml(client.get("http://jandan.net/pic"));
	System.out.println("====开始抓取首页");
	try {
		naviQueue.put(parser.getPageNavi());
		parser.handleImgs(imgQueue);
	} catch (InterruptedException e) {
	}
	client.close();
	System.out.println("首页结束，开始执行多线程抓取");
	begin.countDown();
}

class PageThread implements Runnable {
		private final CountDownLatch startSignal;
		private final CountDownLatch stopSignal;
		private int index;
		public PageThread(int index, CountDownLatch start, CountDownLatch end) {
			this.startSignal = start;
			this.stopSignal = end;
			this.index = index;
		}
		@Override
		public void run() {
			try {
				startSignal.await();
			} catch (Exception e) {
			}
			String html = "";
			String url = "";
			int left = 0;
			HtmlParser parser = new HtmlParser();
			SimpleHttpClient client = new SimpleHttpClient();
			while (true) {
				try {
					url = naviQueue.take();
					left = naviQueue.size();
					if ("".equals(url)) {
						// 把结束的标志放回去，其他的线程也要调用
						naviQueue.put("");
						break;
					}
				} catch (Exception e) {
					System.err.println("[" + index + "]:" + e.getMessage());
				}
				System.out.println("[" + index + "][页面left:" + left
						+ "]线程抓取html-->" + url);
				try {
					html = client.get(url);
				} catch (Exception e1) {
				}
				parser.setHtml(html);
				String next = parser.getPageNavi();
				try {
					if (next == null) {
						naviQueue.put("");
						parser.handleImgs(imgQueue); // 在图片队列的最后也放上一个""作为结束的标志
						imgQueue.put("");
					} else {
						naviQueue.put(next);
						parser.handleImgs(imgQueue);
					}
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
			client.close();
			stopSignal.countDown();
		}
	}

class ImageThread implements Runnable {
	private final CountDownLatch startSignal;
	private final CountDownLatch stopSignal;
	private int threadIdx;
	private String dest;
	public ImageThread(int index, String dest, CountDownLatch start,
			CountDownLatch end) {
		this.threadIdx = index;
		this.dest = dest;
		this.startSignal = start;
		this.stopSignal = end;
	}
	@Override
	public void run() {
		try {
			// 等待初始的线程结束
			startSignal.await();
		} catch (Exception e) {
		}
		System.out.println("[" + threadIdx + "]线程开始");
		SimpleHttpClient client = new SimpleHttpClient();
		String picurl = "";
		int left = 0;
		// 这个线程不断的从图片队列里面取出图片的地址
		while (true) {
			// 取出一个图片地址
			try {
				picurl = imgQueue.take();
				left = imgQueue.size();
			} catch (InterruptedException e1) {
				System.err
						.println("[" + threadIdx + "]:" + e1.getMessage());
			}
			if ("".equals(picurl)) {
				try {
					// 结束标志，丢回去，其他的线程要根据这个判断结束
					imgQueue.put("");
				} catch (Exception e) {
					e.printStackTrace();
				}
				// 如果说，取到图片地址为空而且页面的已经解析完毕，这个就应该要结束了。
				break;
			}
			try {
				System.out.println("[" + threadIdx + "][图片left:" + left
						+ "]线程开始抓取image-->" + picurl);
				client.downloadFile(picurl, dest);
			} catch (Exception e) {
				System.err.println("[" + threadIdx + "]:" + e.getMessage());
			}
		}
		client.close();
		stopSignal.countDown();
	}
}