Properties配置文件修改后重读的功能

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URL;
import java.util.Properties;

/**
 * Properties配置文件修改后重读的功能
 * 
 * @author Administrator
 * 
 */
public class ConfigUtil {

	private static Properties props = null;
	private static File configFile = null;
	private static long fileLastModified = 0L;

	private static void init() {
		URL url = ConfigUtil.class.getClassLoader().getResource(
				"global.properties");//global.properties放到WEB-INF/classes/
		configFile = new File(url.getFile());
		fileLastModified = configFile.lastModified();
		props = new Properties();
		load();
	}

	private static void load() {
		try {
			props.load(new FileInputStream(configFile));
			fileLastModified = configFile.lastModified();
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	public static String getConfig(String key) {
		if ((configFile == null) || (props == null))
			init();
		if (configFile.lastModified() > fileLastModified)
			load();
		return props.getProperty(key);
	}
	
	public static void main(String[] arg){
		String userName = ConfigUtil.getConfig("userName");
		System.out.println(userName);
	}

}