SimpleDateFormat 은 Thread-safe 하지 않다.
멀티스레드에서 동시에 사용하면 이상한 오류가 나거나 Date 객체가 올바르게 생성되지 않는다(시간이 잘못 나온다).
public class CommonUtils {
private static Logger logger = LoggerFactory.getLogger(CommonUtils.class);
private static SimpleDateFormat ORIGIN_FORMAT_TYPE_1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.KOREAN);
private static SimpleDateFormat ORIGIN_FORMAT_TYPE_2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.KOREAN);
private static SimpleDateFormat TRANS_FORMAT = new SimpleDateFormat("yyyy.MM.dd. (EEE) hh:mm:ss", Locale.KOREAN);
private static SimpleDateFormat TRANS_FORMAT_AM_PM = new SimpleDateFormat(" a", Locale.US); // Locale.KOREAN 으로 하면 '오전/오후'로 표기되므로, 해당부분만 Locale.US로 설정하여 문자열을 조합한다.
private static SimpleDateFormat TRANS_FORMAT_FOR_HOTTOPIC = new SimpleDateFormat("yyyy.MM.dd HH:mm", Locale.KOREAN);
// ...
switch (type) {
case 1 :
to = ORIGIN_FORMAT_TYPE_1.parse(dateString); // 이 부분!!! ****
break;
case 2 :
to = ORIGIN_FORMAT_TYPE_2.parse(dateString); // 이 부분!!! ****
break;
default:
throw new ParseException(dateString, type);
}
java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Long.parseLong(Long.java:431)
at java.lang.Long.parseLong(Long.java:468)
at java.text.DigitList.getLong(DigitList.java:177)
at java.text.DecimalFormat.parse(DecimalFormat.java:1298)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1936)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1312)
at java.text.DateFormat.parse(DateFormat.java:335)
java.lang.NumberFormatException: multiple points
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1082)
at java.lang.Double.parseDouble(Double.java:510)
at java.text.DigitList.getDouble(DigitList.java:151)
at java.text.DecimalFormat.parse(DecimalFormat.java:1303)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1936)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1312)
at java.text.DateFormat.parse(DateFormat.java:335)
java.lang.NumberFormatException: For input string: ".30"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Long.parseLong(Long.java:410)
at java.lang.Long.parseLong(Long.java:468)
at java.text.DigitList.getLong(DigitList.java:177)
at java.text.DecimalFormat.parse(DecimalFormat.java:1298)
at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1934)
at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1312)
at java.text.DateFormat.parse(DateFormat.java:335)
// 문제가 되는 부분
final SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
ExecutorService executorService = Executors.newCachedThreadPool();
for (int i = 0; i < 2; i++) {
executorService.execute(new Runnable() {
@Override
public void run() {
try {
System.out.println(simpleDateFormat.parse("2017-03-22 16:00:00"));
} catch (ParseException e) {
e.printStackTrace();
}
}
});
}
(1) 예외가 발생하거나
(2) 잘못된 시간으로 나옴
