热加载Properties 工具类

package com.bow.utils.common;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;

/**
*该工具支持properties修改热加载
*loadFile(String fileUrl)
*getProperty(String key, String defaultValue)
*两方法是同步的，不能并行
* @author acer
* @version C10 2016年5月16日
*/
public class PropertiesUtil
{
private static final Logger logger = LoggerFactory.getLogger(PropertiesUtil.class);

/**
* 默认加载的properties文件
*/
private static final String[] DEFAULT_PROPERTIES_URL = {"conf/business/system.properties"};

private static final int LOAD_INTERVAL_SECONDS = 120;

/**
* properties 所有property的容器
*/
private static Properties properties = new Properties();

static
{
for (String url : DEFAULT_PROPERTIES_URL)
{
loadFile(url);
}
monitor();
}

private static synchronized void loadFile(String fileUrl)
{
// class.getResourceAsStream路径用相对话是相对于本class所在位置。也可以用绝对的如/conf/business/system.properties
// InputStream is = PropertiesUtil.class.getResourceAsStream(fileUrl);
// 此处注意ClassLoader.getResourceAsStream只能用相对于classpath的绝对路径,并且不能已 / 开头
InputStream is = PropertiesUtil.class.getClassLoader().getResourceAsStream(fileUrl);

try
{
properties.load(is);
}
catch (IOException e)
{
logger.error("IOException when load" + fileUrl, e);
}
finally
{
try
{
is.close();
}
catch (IOException e)
{
logger.error("IOException when close inputStream " + fileUrl, e);
}
}
}

/**
* 守护线程每隔LOAD_INTERVAL_SECONDS秒去加载一次properties
*/
private static void monitor()
{
Thread t = new Thread(new Runnable()
{
@Override
public void run()
{

try
{
TimeUnit.SECONDS.sleep(LOAD_INTERVAL_SECONDS);
for (String url : DEFAULT_PROPERTIES_URL)
{
loadFile(url);
}
}
catch (InterruptedException e)
{
logger.error("properties-monitor-thread Interrupted", e);
}
}

}, "properties-monitor-thread");
// 设置为守护线程后，用户线程结束，此线程立即中断
t.setDaemon(true);
t.start();

}
public static String getProperty(String key)
{
return getProperty(key, null);
}

public static synchronized String getProperty(String key, String defaultValue)
{
Assert.notNull(key, "key can not be null");
return properties.getProperty(key) == null ? defaultValue : properties.getProperty(key);
}
}