Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY) -1);//當前時間的前一小時舉例
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");

String end=dateFormat.format(new Date());//將本地日期格式化為UTC格式的 日期字串

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//字串轉Date
String stringDate = "Thu Oct 16 07:13:48 GMT 2015";
SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM ddHH:mm:ss 'GMT' yyyy",Locale.US);
Date date =sdf.parse(stringDate);
System.out.println(date.toString());

//Date轉字串
sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");    
System.out.println(sdf.format(new Date()));
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//T代表後面跟著時間，Z代表UTC統一時間
//格式化時間
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
String time = sdf.format(new Date());
System.out.println(time);

//解析時間 2016-01-05T15:09:54Z
Date date = sdf.parse(time);
System.out.println(date);