//(旧)格式化时间，Jdk7：

//将时间字符串转化为标准时间格式

String accessTime = "20181212162923";

if (accessTime != null && accessTime.trim().length() != 0) {

Date time = new Date();

//2018-09-09 19:15:14

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss", Locale.US);

try {

time = sdf.parse(accessTime);

} catch (ParseException e) {

}

SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX");

accessTime = sdf2.format(time);

System.out.println(accessTime);

}

//输出：2018-12-12T16:29:23+08:00

//(新)JDK1.8将字符串转换为标准的ISO-8601的时间格式：

//(新)将字符串转换为标准的ISO-8601的时间格式

String timestamp = "20181212162923";

try {

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");

LocalDateTime dt1 = LocalDateTime.parse(timestamp,formatter);

ZoneOffset offset = ZoneOffset.of("+08:00");

OffsetDateTime date = OffsetDateTime.of(dt1,offset);

DateTimeFormatter formatter2=DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ssXXX");

timestamp=date.format(formatter2);

System.out.println(timestamp);

}

catch (DateTimeParseException ex) {

ex.printStackTrace();

}

//结果：2018-12-12T16:29:23+08:00

//(新)jdk8 LocalDateTime和字符串互相转换：

//字符串-->>LocalDateTime

DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

LocalDateTime localDateTime = LocalDateTime.parse("2017-07-20 15:27:44", dateTimeFormatter);

System.out.println("字符串转LocalDateTime: " + localDateTime);

//输出：字符串转LocalDateTime: 2017-07-20T15:27:44

//LocalDateTime-->>字符串

DateTimeFormatter dateTimeFormatter2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

String dateString = dateTimeFormatter2.format(LocalDateTime.now());

System.out.println("日期转字符串: " + dateString);

//输出：日期转字符串: 2019-07-17 09:35:53

//(新)获取时区：

//获取时区

System.out.println(LocalDateTime.now(ZoneOffset.systemDefault()).atZone(ZoneOffset.systemDefault()).getOffset());

//输出：+08:00