监听文件修改，自动加载xml文件。

转载文章，转载自，公司项目，董亚杰写的。

下面是完整的代码，复制的。

package cn.digitalpublishing.util.debug;

import java.io.File;
import java.nio.file.FileSystems;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;

import org.apache.commons.io.FilenameUtils;

import cn.digitalpublishing.util.SpringUtils;

import com.ingenta.framework.dao.impl.support.DefaultIngentaDao;

/**
 *
 * @author dongyajie
 *
 */
@WebServlet(initParams = { @WebInitParam(name = "path", value = "W:\\workspace2\\Editorial\\src\\main\\resources\\sql") }, value = "/DynamicReloadHqlXmlNew", loadOnStartup = 88)
public class DynamicReloadHqlXmlNew extends HttpServlet {

	private static final long serialVersionUID = 1L;

	private final String ACTION_ENTRY_CREATE = "ENTRY_CREATE";
	private final String ACTION_ENTRY_DELETE = "ENTRY_DELETE";
	private final String ACTION_ENTRY_MODIFY = "ENTRY_MODIFY";

	private String prevFileName = "";
	private String prevAction = "";
	private long prevTimeMillis = 0;
	private final long interval = 500;
	private DefaultIngentaDao dao;

	@Override
	public void init(ServletConfig config) throws ServletException {
		final String hqlDir = config.getInitParameter("path");
		dao = (DefaultIngentaDao) SpringUtils.getBean("ingentaDao");
		ExecutorService service = Executors.newSingleThreadExecutor();
		service.execute(new Runnable() {
			@Override
			public void run() {
				WatchService watchService = null;
				try {
					watchService = FileSystems.getDefault().newWatchService();
					Paths.get(hqlDir).register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
				} catch (Exception e) {
				}
				if (watchService != null) {
					while (true) {
						try {
							WatchKey key = watchService.take();
							List<WatchEvent<?>> events = key.pollEvents();
							if (!events.isEmpty()) {
								WatchEvent<?> event = events.get(events.size() - 1);
								File eventFile = new File(hqlDir, event.context().toString());
								Kind<?> eventKind = event.kind();
								String kindName = eventKind.name();
								if (eventKind.name().equals(ACTION_ENTRY_CREATE)) {
									kindName = ACTION_ENTRY_MODIFY;
								}
								if ((!eventFile.getPath().equals(prevFileName) || !kindName.equals(prevAction)) || ((System.currentTimeMillis() - prevTimeMillis) > interval)) {
									if (eventFile.isFile()) {
										if (kindName.equals(ACTION_ENTRY_MODIFY)) {
											if (FilenameUtils.isExtension(eventFile.getName().toLowerCase(), "xml")) {
												loadXML(eventFile.getPath());
											}
										}
									}
									if (kindName.equals(ACTION_ENTRY_DELETE)) {
									}
									prevAction = kindName;
									prevFileName = eventFile.getPath();
									prevTimeMillis = System.currentTimeMillis();
								}
							}
							if (!key.reset()) {
								break;
							}
						} catch (Exception e) {
						}
					}
				}
			}
		});
		service.shutdown();
	}

	private synchronized void loadXML(String filename) {
		String logfn = FilenameUtils.getName(filename);
		try {
			dao.loadResource(new File(filename));
			System.err.println(logfn + " 加载完成");
		} catch (Exception e) {
			System.err.println(logfn + " 加载失败" + e.getMessage());
		}
	}
}

反正，暂时我是看不懂，感觉太高端了，总有一天我有看懂的时候，，，，，

大神，工作经验5年，编程经验，10年，90后。