类 SingleColumnRowMapper<T>

构造器详细资料

• SingleColumnRowMapper

  public SingleColumnRowMapper()

  Create a new SingleColumnRowMapper for bean-style configuration.

  另请参阅:

  setRequiredType(java.lang.Class<T>)

• SingleColumnRowMapper

  public SingleColumnRowMapper​(Class<T> requiredType)

  Create a new SingleColumnRowMapper.

  参数:

  requiredType - the type that each result object is expected to match

方法详细资料

• setRequiredType

  public void setRequiredType​(Class<T> requiredType)

  Set the type that each result object is expected to match.

  If not specified, the column value will be exposed as returned by the JDBC driver.

• setConversionService

  public void setConversionService​(@Nullable
                                   ConversionService conversionService)

  Set a ConversionService for converting a fetched value.

  Default is the DefaultConversionService.

  从以下版本开始:

  5.0.4

  另请参阅:

  DefaultConversionService.getSharedInstance()

• mapRow

  @Nullable
  public T mapRow​(ResultSet rs,
                  int rowNum)
           throws SQLException

  Extract a value for the single column in the current row.

  Validates that there is only one column selected, then delegates to getColumnValue() and also convertValueToRequiredType, if necessary.

  指定者:

  mapRow 在接口中 RowMapper<T>

  参数:

  rs - the ResultSet to map (pre-initialized for the current row)

  rowNum - the number of the current row

  返回:

  the result object for the current row (may be null)

  抛出:

  SQLException - if an SQLException is encountered getting column values (that is, there's no need to catch SQLException)

  另请参阅:

  ResultSetMetaData.getColumnCount(), getColumnValue(java.sql.ResultSet, int, Class), convertValueToRequiredType(Object, Class)

• getColumnValue

  @Nullable
  protected Object getColumnValue​(ResultSet rs,
                                  int index,
                                  @Nullable
                                  Class<?> requiredType)
                           throws SQLException

  Retrieve a JDBC object value for the specified column.

  The default implementation calls JdbcUtils.getResultSetValue(java.sql.ResultSet, int, Class). If no required type has been specified, this method delegates to getColumnValue(rs, index), which basically calls ResultSet.getObject(index) but applies some additional default conversion to appropriate value types.

  参数:

  rs - is the ResultSet holding the data

  index - is the column index

  requiredType - the type that each result object is expected to match (or null if none specified)

  返回:

  the Object value

  抛出:

  SQLException - in case of extraction failure

  另请参阅:

  JdbcUtils.getResultSetValue(java.sql.ResultSet, int, Class), getColumnValue(java.sql.ResultSet, int)

• getColumnValue

  @Nullable
  protected Object getColumnValue​(ResultSet rs,
                                  int index)
                           throws SQLException

  Retrieve a JDBC object value for the specified column, using the most appropriate value type. Called if no required type has been specified.

  The default implementation delegates to JdbcUtils.getResultSetValue(), which uses the ResultSet.getObject(index) method. Additionally, it includes a "hack" to get around Oracle returning a non-standard object for their TIMESTAMP datatype. See the JdbcUtils#getResultSetValue() javadoc for details.

  参数:

  rs - is the ResultSet holding the data

  index - is the column index

  返回:

  the Object value

  抛出:

  SQLException - in case of extraction failure

  另请参阅:

  JdbcUtils.getResultSetValue(java.sql.ResultSet, int)

• convertValueToRequiredType

  @Nullable
  protected Object convertValueToRequiredType​(Object value,
                                              Class<?> requiredType)

  Convert the given column value to the specified required type. Only called if the extracted column value does not match already.

  If the required type is String, the value will simply get stringified via toString(). In case of a Number, the value will be converted into a Number, either through number conversion or through String parsing (depending on the value type). Otherwise, the value will be converted to a required type using the ConversionService.

  参数:

  value - the column value as extracted from getColumnValue() (never null)

  requiredType - the type that each result object is expected to match (never null)

  返回:

  the converted value

  另请参阅:

  getColumnValue(java.sql.ResultSet, int, Class)

• newInstance

  public static <T> SingleColumnRowMapper<T> newInstance​(Class<T> requiredType)

  Static factory method to create a new SingleColumnRowMapper.

  参数:

  requiredType - the type that each result object is expected to match

  从以下版本开始:

  4.1

  另请参阅:

  newInstance(Class, ConversionService)

• newInstance

  public static <T> SingleColumnRowMapper<T> newInstance​(Class<T> requiredType,
                                                         @Nullable
                                                         ConversionService conversionService)

  Static factory method to create a new SingleColumnRowMapper.

  参数:

  requiredType - the type that each result object is expected to match

  conversionService - the ConversionService for converting a fetched value, or null for none

  从以下版本开始:

  5.0.4

  另请参阅:

  newInstance(Class), setConversionService(org.springframework.core.convert.ConversionService)