class LogUtil{
public static LogUtil getInstance() {
if (sLogUtil == null) {
synchronized (LogUtil.class) {
if (sLogUtil == null) {
sLogUtil = new LogUtil();
}
}
}
return sLogUtil;
}
}
加双重同步锁，防止多线实例化
原文：http://www.cnblogs.com/maliu/p/5260291.html