Interface Adapter

  • All Superinterfaces:
    Serializable
    All Known Implementing Classes:
    AbstractAdapter, DerbyAdapter, HsqldbAdapter, MssqlAdapter, MysqlAdapter, NoneAdapter, OracleAdapter, PostgresAdapter

    public interface Adapter
    extends Serializable
    DB defines the interface for a Torque database adapter. Support for new databases is added by implementing this interface. A couple of default settings is provided by subclassing AbstractDBAdapter. The new database adapter and its corresponding JDBC driver need to be registered in the service configuration file.

    The Torque database adapters exist to present a uniform interface to database access across all available databases. Once the necessary adapters have been written and configured, transparent swapping of databases is theoretically supported with zero code changes and minimal configuration file modifications. All database adapters need to be thread safe, as they are instantiated only once fore a given configured database and may be accessed simultaneously from several threads. *

    Version:
    $Id: Adapter.java 1850586 2019-01-06 18:46:35Z tv $
    Author:
    Jon S. Stevens, Brett McLaughlin, Daniel Rall, Augustin Vidovic, Thomas Vandahl, Greg Monroe
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static String ADAPTER_KEY
      Key for the configuration which contains database adapters.
      static String AUTODETECT_ADAPTER
      Special adapter for auto-detection.
      static String DRIVER_KEY
      Key for the configuration which contains database drivers.
    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      boolean escapeText()
      Determines whether backslashes (\) should be escaped in explicit SQL strings.
      void generateLimits​(Query query, long offset, int limit)
      This method is used to generate the database specific query extension to limit the number of record returned.
      String getIDMethodSQL​(Object obj)
      Returns SQL used to get the most recently inserted primary key.
      IDMethod getIDMethodType()
      Returns the constant from the IDMethod interface denoting which type of primary key generation method this type of RDBMS uses.
      char getStringDelimiter()
      Returns the character used to indicate the beginning and end of a piece of text used in a SQL statement (generally a single quote).
      String getUpdateLockClause()
      Returns the clause which acquires a write lock on a row when doing a select.
      String ignoreCase​(String in)
      Wraps the input string in a database function to change it to a case-insensitive representation.
      String ignoreCaseInOrderBy​(String in)
      This method is used to ignore case in an ORDER BY clause.
      void lockTable​(Connection con, String table)
      Locks the specified table.
      void setCapabilities​(DatabaseMetaData dmd)
      Update static capabilities of the adapter with actual readings based on the JDBC meta-data
      boolean supportsNativeLimit()
      This method is used to check whether the database natively supports limiting the size of the resultset.
      boolean supportsNativeOffset()
      This method is used to check whether the database natively supports returning results starting at an offset position other than 0.
      String toUpperCase​(String in)
      Wraps the input string in a database function to change it to upper case.
      void unlockTable​(Connection con, String table)
      Unlocks the specified table.
      boolean useEscapeClauseForLike()
      Whether an escape clause in like should be used.
      boolean useGetGeneratedKeys()
      whether Statement#getGeneratedKeys() should be used.
      boolean useIlike()
      Whether ILIKE should be used for case insensitive like clauses.
      boolean useMinusForExcept()
      Whether to use the MINUS operator instead of the EXCEPT operator.
    • Method Detail

      • toUpperCase

        String toUpperCase​(String in)
        Wraps the input string in a database function to change it to upper case.
        Parameters:
        in - The string to transform to upper case, may be a literal string, a prepared statement replacement placeholder(*) or any other database expression.
        Returns:
        The wrapped input string, so that the database evaluates the returned expression to the upper case of the input.
      • getStringDelimiter

        char getStringDelimiter()
        Returns the character used to indicate the beginning and end of a piece of text used in a SQL statement (generally a single quote).
        Returns:
        The text delimiter.
      • getIDMethodType

        IDMethod getIDMethodType()
        Returns the constant from the IDMethod interface denoting which type of primary key generation method this type of RDBMS uses.
        Returns:
        IDMethod constant
      • getIDMethodSQL

        String getIDMethodSQL​(Object obj)
        Returns SQL used to get the most recently inserted primary key. Databases which have no support for this return null.
        Parameters:
        obj - Information used for key generation.
        Returns:
        The most recently inserted database key.
      • getUpdateLockClause

        String getUpdateLockClause()
        Returns the clause which acquires a write lock on a row when doing a select. Most databases use the "for update" clause.
        Returns:
        the SQL clause to acquire a write lock.
      • lockTable

        void lockTable​(Connection con,
                       String table)
                throws SQLException
        Locks the specified table.
        Parameters:
        con - The JDBC connection to use.
        table - The name of the table to lock.
        Throws:
        SQLException - No Statement could be created or executed.
      • unlockTable

        void unlockTable​(Connection con,
                         String table)
                  throws SQLException
        Unlocks the specified table.
        Parameters:
        con - The JDBC connection to use.
        table - The name of the table to unlock.
        Throws:
        SQLException - No Statement could be created or executed.
      • ignoreCase

        String ignoreCase​(String in)
        Wraps the input string in a database function to change it to a case-insensitive representation.
        Parameters:
        in - The string to transform to a case-insensitive representation, may be a literal string, a prepared statement replacement placeholder(*) or any other database expression.
        Returns:
        The wrapped input string, so that the database evaluates the returned expression to a case-insensitive representation of the input.
      • ignoreCaseInOrderBy

        String ignoreCaseInOrderBy​(String in)
        This method is used to ignore case in an ORDER BY clause. Usually it is the same as ignoreCase, but some databases (hsqldb for example) does not use the same SQL in ORDER BY and other clauses.
        Parameters:
        in - The string whose case to ignore.
        Returns:
        The string in a case that can be ignored.
      • supportsNativeLimit

        boolean supportsNativeLimit()
        This method is used to check whether the database natively supports limiting the size of the resultset.
        Returns:
        true if the database natively supports limiting the size of the resultset.
      • supportsNativeOffset

        boolean supportsNativeOffset()
        This method is used to check whether the database natively supports returning results starting at an offset position other than 0.
        Returns:
        true if the database natively supports returning results starting at an offset position other than 0.
      • generateLimits

        void generateLimits​(Query query,
                            long offset,
                            int limit)
                     throws TorqueException
        This method is used to generate the database specific query extension to limit the number of record returned.
        Parameters:
        query - The query to modify
        offset - the offset Value
        limit - the limit Value
        Throws:
        TorqueException - if any error occurs when building the query
      • escapeText

        boolean escapeText()
        Determines whether backslashes (\) should be escaped in explicit SQL strings. If true is returned, a BACKSLASH will be changed to "\\". If false is returned, a BACKSLASH will be left as "\".
        Returns:
        true if the database needs to escape backslashes in SqlExpressions.
      • useIlike

        boolean useIlike()
        Whether ILIKE should be used for case insensitive like clauses.
        Returns:
        true if ilike should be used for case insensitive likes, false if ignoreCase should be applied to the compared strings.
      • useEscapeClauseForLike

        boolean useEscapeClauseForLike()
        Whether an escape clause in like should be used. Example : select * from AUTHOR where AUTHOR.NAME like '\_%' ESCAPE '\';
        Returns:
        whether the escape clause should be appended or not.
      • useMinusForExcept

        boolean useMinusForExcept()
        Whether to use the MINUS operator instead of the EXCEPT operator.
        Returns:
        whether to use the MINUS operator instead of the EXCEPT operator.
      • useGetGeneratedKeys

        boolean useGetGeneratedKeys()
        whether Statement#getGeneratedKeys() should be used.
        Returns:
        a boolean value
      • setCapabilities

        void setCapabilities​(DatabaseMetaData dmd)
                      throws SQLException
        Update static capabilities of the adapter with actual readings based on the JDBC meta-data
        Parameters:
        dmd - database meta data
        Throws:
        SQLException - if there are problems getting the JDBC meta data