Java取得Unix的timestamp

//现在时间的TIMESTAMP
long epoch = System.currentTimeMillis()/1000;

//某一时间的TIMESTAMP
Calendar c = Calendar.getInstance();
c.setTime(....);
c.getTimeInMillis()/1000;

Calendar c = Calendar.getInstance();
c.set(2010,3,11); //注意此处,应该是3不是4
c.getTimeInMillis()/1000;