java7 WatchService 您用过吗？

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class ApplicationConfiguration {
    private final static ApplicationConfiguration INSTANCE = new ApplicationConfiguration();
    public static ApplicationConfiguration getInstance() {
        return INSTANCE;
    }
    private static Properties configuration = new Properties();
    private static Properties getConfiguration() {
        return configuration;
    }
    public void initilize(final String file) {
        InputStream in = null;
        try {
            in = new FileInputStream(new File(file));
            configuration.load(in);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public String getConfiguration(final String key) {
        return (String) getConfiguration().get(key);
    }
    public String getConfigurationWithDefaultValue(final String key,
            final String defaultValue) {
        return (String) getConfiguration().getProperty(key, defaultValue);
    }
}

import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
public class ConfigurationChangeListner implements Runnable {
    private String configFileName = null;
    private String fullFilePath = null;
    public ConfigurationChangeListner(final String filePath) {
        this.fullFilePath = filePath;
    }
    public void run() {
        try {
            register(this.fullFilePath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void register(final String file) throws IOException {
        final int lastIndex = file.lastIndexOf("/");
        String dirPath = file.substring(0, lastIndex + 1);
        String fileName = file.substring(lastIndex + 1, file.length());
        this.configFileName = fileName;
        configurationChanged(file);
        startWatcher(dirPath, fileName);
    }
    private void startWatcher(String dirPath, String file) throws IOException {
        final WatchService watchService = FileSystems.getDefault()
                .newWatchService();
        Path path = Paths.get(dirPath);
        path.register(watchService, ENTRY_MODIFY);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            public void run() {
                try {
                    watchService.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        WatchKey key = null;
        while (true) {
            try {
                key = watchService.take();
                for (WatchEvent<?> event : key.pollEvents()) {
                    if (event.context().toString().equals(configFileName)) {
                        configurationChanged(dirPath + file);
                    }
                }
                boolean reset = key.reset();
                if (!reset) {
                    System.out.println("Could not reset the watch key.");
                    break;
                }
            } catch (Exception e) {
                System.out.println("InterruptedException: " + e.getMessage());
            }
        }
    }
    public void configurationChanged(final String file) {
        System.out.println("Refreshing the configuration.");
        ApplicationConfiguration.getInstance().initilize(file);
    }
}

TEST_KEY = TEST_VALUE

public class ConfigChangeTest {
    private static final String FILE_PATH = "C:/Lokesh/temp/test.properties";
    public static void main(String[] args) {
        ConfigurationChangeListner listner = new ConfigurationChangeListner(
                FILE_PATH);
        try {
            new Thread(listner).start();
            while (true) {
                Thread.sleep(2000l);
                System.out.println(ApplicationConfiguration.getInstance()
                        .getConfiguration("TEST_KEY"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
//Output of the above program (Change the TEST_VALUE to TEST_VALUE1 and TEST_VALUE2 using any file editor and save).
Refreshing the configuration.
TEST_VALUE
TEST_VALUE
TEST_VALUE
Refreshing the configuration.
TEST_VALUE1
Refreshing the configuration.
TEST_VALUE2