====== StringDate Hibernate UserType ======
Database에 날짜를 문자열로 저장했을 경우 사용하는 [[java:hibernate:usertype|Hibernate User Type]].

''java.util.Date'' 객체를 문자열로 변환해서 저장하고, 읽을 때 문자열에서 다시 Date 객체로 변환한다.

===== 코드 =====
<code java>
public class StringDateUserType implements UserType, ParameterizedType {

  public static final String PARAM_FORMAT = "format";
  public static final String DEFAULT_FORMAT = "yyyyMMddHHmmss";

  private AbstractSingleColumnStandardBasicType type;
  private int[] sqlTypes = null;
  private String format;

  @Override
  public void setParameterValues(Properties parameters) {
    format = parameters.getProperty(PARAM_FORMAT, DEFAULT_FORMAT);
    populateSqlTypes();
  }

  private void populateSqlTypes() {
    TypeResolver tr = new TypeResolver();
    String stringClassName = String.class.getName();

    // type은 org.hibernate.type.StringType 으로 사실상 고정값임.
    type = (AbstractSingleColumnStandardBasicType) tr.basic(stringClassName);
    sqlTypes = new int[] { type.sqlType() };
  }

  @Override
  public int[] sqlTypes() {
    return sqlTypes;
  }

  @Override
  public Class returnedClass() {
    return Date.class;
  }

  @Override
  public boolean equals(Object x, Object y) throws HibernateException {
    return Objects.equals(x, y);
  }

  @Override
  public int hashCode(Object x) throws HibernateException {
    return Objects.hashCode(x);
  }

  @Override
  public Object deepCopy(Object value) throws HibernateException {
    return dateDeepCopy((Date) value);
  }

  @Override
  public boolean isMutable() {
    return true; // java.util.Date is mutable
  }

  @Override
  public Serializable disassemble(Object value) throws HibernateException {
    // TODO : Date는 mutable이라서 deep copy가 맞는듯. 확인 필요.
    return (Serializable) value;
  }

  @Override
  public Object assemble(Serializable cached, Object owner) throws HibernateException {
    // TODO : Date는 mutable이라서 deep copy가 맞는듯. 확인 필요.
    return cached;
  }

  @Override
  public Object replace(Object original, Object target, Object owner) throws HibernateException {
    return dateDeepCopy((Date) original);
  }

  @Override
  public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner) throws HibernateException, SQLException {
    String stringDate = (String) type.get(rs, names[0], session);
    if (stringDate == null) { // 데이터에 null이 아닌 empty가 있다면 empty 체크도 해야함.
      log.trace("Found [{}] as column [{}] original value [{}]", null, names[0], stringDate);
      return null;
    }

    try {
      SimpleDateFormat sdf = new SimpleDateFormat(format);
      Date parsedDate = sdf.parse(stringDate);
      log.trace("Found [{}] as column [{}] original value [{}]", parsedDate, names[0], stringDate);
      return parsedDate;
    } catch (Exception ex) {
      throw new HibernateException("Failed to parse [" + stringDate + "] with [" + format + "].", ex);
    }
  }

  @Override
  public void nullSafeSet(PreparedStatement st, Object value, int index, SessionImplementor session) throws HibernateException, SQLException {
    try {
      String formattedDate = null;
      if (value != null) {
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        formattedDate = sdf.format((Date) value);
      }
      log.trace("binding parameter [{}] as [{}] - [{}] original value [{}]", index, JdbcTypeNameMapper.getTypeName(sqlTypes[0]), formattedDate, value);
      st.setObject(index, formattedDate);
    } catch (Exception ex) {
      throw new HibernateException("Failed to format date object to string.", ex);
    }
  }

  String getFormat() {
    return format;
  }
}
</code>


===== 설정 =====
<code java>
@TypeDef(name = "string_datetime", typeClass = StringDateUserType.class,
  parameters = @Parameter(name = StringDateUserType.PARAM_FORMAT, value = "yyyy/MM/dd HH:mm:ss")),
// 이제 @Type(type = "string_datetime") 으로 사용가능해짐. 컬럼은 기본적으로 String의 컬럼인 varchar 계열로 지정됨.
</code>