org.springframework.jdbc.support

## Class JdbcUtils

- java.lang.Object
- - org.springframework.jdbc.support.JdbcUtils

-     public abstract class JdbcUtils
      extends Object

  Generic utility methods for working with JDBC. Mainly for internal use within the framework, but also useful for custom JDBC access code.
  Author:
    Thomas Risberg, Juergen Hoeller

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `TYPE_UNKNOWN` Constant that indicates an unknown (or unspecified) SQL type.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `JdbcUtils()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `closeConnection(Connection con)` Close the given JDBC Connection and ignore any thrown exception.
    `static void` | `closeResultSet(ResultSet rs)` Close the given JDBC ResultSet and ignore any thrown exception.
    `static void` | `closeStatement(Statement stmt)` Close the given JDBC Statement and ignore any thrown exception.
    `static String` | `commonDatabaseName(String source)` Extract a common name for the database in use even if various drivers/platforms provide varying names.
    `static String` | `convertUnderscoreNameToPropertyName(String name)` Convert a column name with underscores to the corresponding property name using "camel case".
    `static Object` | `extractDatabaseMetaData(DataSource dataSource, DatabaseMetaDataCallback action)` Extract database meta data via the given DatabaseMetaDataCallback.
    `static Object` | `extractDatabaseMetaData(DataSource dataSource, String metaDataMethodName)` Call the specified method on DatabaseMetaData for the given DataSource, and extract the invocation result.
    `static Object` | `getResultSetValue(ResultSet rs, int index)` Retrieve a JDBC column value from a ResultSet, using the most appropriate value type.
    `static Object` | `getResultSetValue(ResultSet rs, int index, Class requiredType)` Retrieve a JDBC column value from a ResultSet, using the specified value type.
    `static boolean` | `isNumeric(int sqlType)` Check whether the given SQL type is numeric.
    `static String` | `lookupColumnName(ResultSetMetaData resultSetMetaData, int columnIndex)` Determine the column name to use.
    `static boolean` | `supportsBatchUpdates(Connection con)` Return whether the given JDBC driver supports JDBC 2.0 batch updates.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### TYPE_UNKNOWN

          public static final int TYPE_UNKNOWN

      Constant that indicates an unknown (or unspecified) SQL type.
      See Also:
        `Types`, Constant Field Values

  - ### Constructor Detail

    - #### JdbcUtils

          public JdbcUtils()

  - ### Method Detail

    - #### closeConnection

          public static void closeConnection(Connection con)

      Close the given JDBC Connection and ignore any thrown exception. This is useful for typical finally blocks in manual JDBC code.
      Parameters:
        `con` - the JDBC Connection to close (may be `null`)

    - #### closeStatement

          public static void closeStatement(Statement stmt)

      Close the given JDBC Statement and ignore any thrown exception. This is useful for typical finally blocks in manual JDBC code.
      Parameters:
        `stmt` - the JDBC Statement to close (may be `null`)

    - #### closeResultSet

          public static void closeResultSet(ResultSet rs)

      Close the given JDBC ResultSet and ignore any thrown exception. This is useful for typical finally blocks in manual JDBC code.
      Parameters:
        `rs` - the JDBC ResultSet to close (may be `null`)

    - #### getResultSetValue

          public static Object getResultSetValue(ResultSet rs,
                                 int index,
                                 Class requiredType)
                                          throws SQLException

      Retrieve a JDBC column value from a ResultSet, using the specified value type.

      Uses the specifically typed ResultSet accessor methods, falling back to `getResultSetValue(java.sql.ResultSet, int)` for unknown types.

      Note that the returned value may not be assignable to the specified required type, in case of an unknown type. Calling code needs to deal with this case appropriately, e.g. throwing a corresponding exception.

      Parameters:
        `rs` - is the ResultSet holding the data
        `index` - is the column index
        `requiredType` - the required value type (may be `null`)
      Returns:
        the value object
      Throws:
        `SQLException` - if thrown by the JDBC API

    - #### getResultSetValue

          public static Object getResultSetValue(ResultSet rs,
                                 int index)
                                          throws SQLException

      Retrieve a JDBC column value from a ResultSet, using the most appropriate value type. The returned value should be a detached value object, not having any ties to the active ResultSet: in particular, it should not be a Blob or Clob object but rather a byte array respectively String representation.

      Uses the `getObject(index)` method, but includes additional "hacks" to get around Oracle 10g returning a non-standard object for its TIMESTAMP datatype and a `java.sql.Date` for DATE columns leaving out the time portion: These columns will explicitly be extracted as standard `java.sql.Timestamp` object.

      Parameters:
        `rs` - is the ResultSet holding the data
        `index` - is the column index
      Returns:
        the value object
      Throws:
        `SQLException` - if thrown by the JDBC API
      See Also:
        `Blob`, `Clob`, `Timestamp`

    - #### extractDatabaseMetaData

          public static Object extractDatabaseMetaData(DataSource dataSource,
                                       DatabaseMetaDataCallback action)
                                                throws MetaDataAccessException

      Extract database meta data via the given DatabaseMetaDataCallback.

      This method will open a connection to the database and retrieve the database metadata. Since this method is called before the exception translation feature is configured for a datasource, this method can not rely on the SQLException translation functionality.

      Any exceptions will be wrapped in a MetaDataAccessException. This is a checked exception and any calling code should catch and handle this exception. You can just log the error and hope for the best, but there is probably a more serious error that will reappear when you try to access the database again.

      Parameters:
        `dataSource` - the DataSource to extract metadata for
        `action` - callback that will do the actual work
      Returns:
        object containing the extracted information, as returned by the DatabaseMetaDataCallback's `processMetaData` method
      Throws:
        `MetaDataAccessException` - if meta data access failed

    - #### extractDatabaseMetaData

          public static Object extractDatabaseMetaData(DataSource dataSource,
                                       String metaDataMethodName)
                                                throws MetaDataAccessException

      Call the specified method on DatabaseMetaData for the given DataSource, and extract the invocation result.
      Parameters:
        `dataSource` - the DataSource to extract meta data for
        `metaDataMethodName` - the name of the DatabaseMetaData method to call
      Returns:
        the object returned by the specified DatabaseMetaData method
      Throws:
        `MetaDataAccessException` - if we couldn't access the DatabaseMetaData or failed to invoke the specified method
      See Also:
        `DatabaseMetaData`

    - #### supportsBatchUpdates

          public static boolean supportsBatchUpdates(Connection con)

      Return whether the given JDBC driver supports JDBC 2.0 batch updates.

      Typically invoked right before execution of a given set of statements: to decide whether the set of SQL statements should be executed through the JDBC 2.0 batch mechanism or simply in a traditional one-by-one fashion.

      Logs a warning if the "supportsBatchUpdates" methods throws an exception and simply returns `false` in that case.

      Parameters:
        `con` - the Connection to check
      Returns:
        whether JDBC 2.0 batch updates are supported
      See Also:
        `DatabaseMetaData.supportsBatchUpdates()`

    - #### commonDatabaseName

          public static String commonDatabaseName(String source)

      Extract a common name for the database in use even if various drivers/platforms provide varying names.
      Parameters:
        `source` - the name as provided in database metedata
      Returns:
        the common name to be used

    - #### isNumeric

          public static boolean isNumeric(int sqlType)

      Check whether the given SQL type is numeric.
      Parameters:
        `sqlType` - the SQL type to be checked
      Returns:
        whether the type is numeric

    - #### lookupColumnName

          public static String lookupColumnName(ResultSetMetaData resultSetMetaData,
                                int columnIndex)
                                         throws SQLException

      Determine the column name to use. The column name is determined based on a lookup using ResultSetMetaData.

      This method implementation takes into account recent clarifications expressed in the JDBC 4.0 specification:

      columnLabel - the label for the column specified with the SQL AS clause. If the SQL AS clause was not specified, then the label is the name of the column.

      Parameters:
        `resultSetMetaData` - the current meta data to use
        `columnIndex` - the index of the column for the look up
      Returns:
        the column name to use
      Throws:
        `SQLException` - in case of lookup failure

    - #### convertUnderscoreNameToPropertyName

          public static String convertUnderscoreNameToPropertyName(String name)

      Convert a column name with underscores to the corresponding property name using "camel case". A name like "customer_number" would match a "customerNumber" property name.
      Parameters:
        `name` - the column name to be converted
      Returns:
        the name using "camel case"