不重启动服务器动态加载properties文件改动

package com;

import java.io.File;

import java.io.FileInputStream;

import java.net.URL;

import java.util.Properties;

import org.apache.log4j.helpers.Loader;

/**

* <li>;Project: test

* <li>File Name: ConfigManager.java

* <li>Title: ConfigManager

* <li>Description: 从《Java 与 模式》中找到的一个可以管理properties文件的管理器，

* 可以处理文件在系统运行期间的改动。采用了单例模式

* <li>Copyright: Copyright (c) 2000-2005

* <li>Company:

*

* @author no Author 访问方式示例： Object

* o=ConfigManager.getInstance().getConfigItem(key,null); if(o==null){

* throw new Exception("System 获取字符串" + key + "失败！"); }

*

*

*/

public class ConfigManager {

private static ConfigManager m_instance;

private static String PFILE;

synchronized public static ConfigManager getInstance() {

if (m_instance == null) {

if (PFILE == null) {

URL url = Loader.getResource("./my_config.properties");

PFILE = url.getPath();

PFILE = StringUtil.replaceAll(PFILE, "%20", " ");

}

m_instance = new ConfigManager();

}

return m_instance;

}

private File m_file = null;

private long m_lastModifiedTime = 0;

private Properties m_props = null;

private ConfigManager() {

m_file = new File(PFILE);

m_lastModifiedTime = m_file.lastModified();

if (m_lastModifiedTime == 0) {

System.err.println(PFILE + " file does not exist!");

}

m_props = new Properties();

try {

m_props.load(new FileInputStream(PFILE));

} catch (Exception e) {

e.printStackTrace();

}

}

final public Object getConfigItem(String name, Object defaultVal) {

long newTime = m_file.lastModified();

if (newTime == 0) {

if (m_lastModifiedTime == 0) {

System.err.println(PFILE + " file does not exist!");

} else {

System.err.println(PFILE + " file was deleted!!");

}

return defaultVal;

} else if (newTime > m_lastModifiedTime) {

m_props.clear();

try {

m_props.load(new FileInputStream(PFILE));

} catch (Exception e) {

e.printStackTrace();

}

}

m_lastModifiedTime = newTime;

Object val = m_props.getProperty(name);

if (val == null) {

return defaultVal;

} else {

return val;

}

}

}