java-工具类-读取配置文件

java读取配置文件，当发现文件被修改后则重新加载

package com.zg.config;

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

/**
 * 系统配置文件读取
 * @author huage
 *
 */
public class SysConfig {
    private static Properties props = null;
    private static File configFile = null;
    private static long fileLastModified = 0L; 

    private static String configFileName = "properties/sys/system.properties";

    private static void init() {
        URL url = SysConfig.class.getClassLoader().getResource(configFileName); 

        configFile = new File(url.getFile());
        fileLastModified = configFile.lastModified();
        props = new Properties();
        load();
    } 

    private static void load() {
        try {
            props.load(new InputStreamReader(new FileInputStream(configFile),"UTF-8"));
            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(); //当检测到文件被修改时重新加载配置文件
        return props.getProperty(key);
    } 

    public static void main(String[] args){
        System.out.println(getConfig("sys.index.name"));
    }}