org.apache.torque.adapter
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 1355228 2012-06-29 03:38:08Z tfischer $

Author:

Jon S. Stevens, Brett McLaughlin, Daniel Rall, Augustin Vidovic, Thomas Vandahl, Greg Monroe

Field Summary

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

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	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.
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.
TorqueException	toTorqueException(SQLException e) Creates a Torque exception from a database-specific exception.
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	useIlike() Whether ILIKE should be used for case insensitive like clauses.

Field Detail

ADAPTER_KEY

static final String ADAPTER_KEY

Key for the configuration which contains database adapters.

See Also:

Constant Field Values

DRIVER_KEY

static final String DRIVER_KEY

Key for the configuration which contains database drivers.

See Also:

Constant Field Values

AUTODETECT_ADAPTER

static final String AUTODETECT_ADAPTER

Special adapter for auto-detection.

See Also:

Constant Field Values

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.

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.

toTorqueException

TorqueException toTorqueException(SQLException e)

Creates a Torque exception from a database-specific exception.

Parameters:

e - the database-specific exception to create the exception from

Returns:

the corresponding Torque exception, possibly a subclass.