Package org.apache.torque.adapter
Klasse AbstractAdapter
java.lang.Object
org.apache.torque.adapter.AbstractAdapter
- Alle implementierten Schnittstellen:
Serializable
,Adapter
- Bekannte direkte Unterklassen:
DerbyAdapter
,HsqldbAdapter
,MssqlAdapter
,MysqlAdapter
,NoneAdapter
,OracleAdapter
,PostgresAdapter
This class is the abstract base for any database adapter
Support for new databases is added by subclassing this
class and implementing its abstract methods, and by
registering the new database adapter and its corresponding
JDBC driver 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.
- Version:
- $Id: AbstractAdapter.java 1917245 2024-04-21 14:06:23Z tv $
- Autor:
- Jon S. Stevens, Brett McLaughlin, Daniel Rall, Augustin Vidovic, Greg Monroe
- Siehe auch:
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Feldübersicht
Von Schnittstelle geerbte Felder org.apache.torque.adapter.Adapter
ADAPTER_KEY, AUTODETECT_ADAPTER, DRIVER_KEY
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Konstruktorübersicht
Konstruktoren -
Methodenübersicht
Modifizierer und TypMethodeBeschreibungboolean
This method is for the SqlExpression.quoteAndEscape rules.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.abstract String
getIDMethodSQL
(Object obj) Returns SQL used to get the most recently inserted primary key.abstract IDMethod
Returns the constant from theIDMethod
interface denoting which type of primary key generation method this type of RDBMS uses.char
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 clause which acquires a write lock on a row when doing a select.abstract String
ignoreCase
(String in) Wraps the input string in a database function to change it to a case-insensitive representation.This method is used to ignore case in an ORDER BY clause.abstract void
lockTable
(Connection con, String table) Locks the specified table.void
Update static capabilities of the adapter with actual readings based on the JDBC meta-databoolean
Returns whether the database can natively limit the size of the ResultSet of a query.boolean
Returns whether the database natively supports returning results starting at an offset position other than 0.abstract String
toUpperCase
(String in) Wraps the input string in a database function to change it to upper case.abstract void
unlockTable
(Connection con, String table) Unlocks the specified table.boolean
Whether an escape clause in like should be used.boolean
whether Statement#getGeneratedKeys() should be used.boolean
useIlike()
Whether ILIKE should be used for case insensitive like clauses.boolean
Whether to use the MINUS operator instead of the EXCEPT operator.
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Konstruktordetails
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AbstractAdapter
protected AbstractAdapter()Empty constructor.
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Methodendetails
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toUpperCase
Wraps the input string in a database function to change it to upper case.- Angegeben von:
toUpperCase
in SchnittstelleAdapter
- Parameter:
in
- The string to transform to upper case, may be a literal string, a prepared statement replacement placeholder(*) or any other database expression.- Gibt zurück:
- The wrapped input string, so that the database evaluates the returned expression to the upper case of the input.
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getStringDelimiter
public 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).- Angegeben von:
getStringDelimiter
in SchnittstelleAdapter
- Gibt zurück:
- The text delimiter.
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getIDMethodType
Returns the constant from theIDMethod
interface denoting which type of primary key generation method this type of RDBMS uses.- Angegeben von:
getIDMethodType
in SchnittstelleAdapter
- Gibt zurück:
- IDMethod constant
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getIDMethodSQL
Returns SQL used to get the most recently inserted primary key. Databases which have no support for this returnnull
.- Angegeben von:
getIDMethodSQL
in SchnittstelleAdapter
- Parameter:
obj
- Information used for key generation.- Gibt zurück:
- The most recently inserted database key.
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getUpdateLockClause
Returns the clause which acquires a write lock on a row when doing a select.- Angegeben von:
getUpdateLockClause
in SchnittstelleAdapter
- Gibt zurück:
- the SQL clause to acquire a write lock. This implementation returns "FOR UPDATE";
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lockTable
Locks the specified table.- Angegeben von:
lockTable
in SchnittstelleAdapter
- Parameter:
con
- The JDBC connection to use.table
- The name of the table to lock.- Löst aus:
SQLException
- No Statement could be created or executed.
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unlockTable
Unlocks the specified table.- Angegeben von:
unlockTable
in SchnittstelleAdapter
- Parameter:
con
- The JDBC connection to use.table
- The name of the table to unlock.- Löst aus:
SQLException
- No Statement could be created or executed.
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ignoreCase
Wraps the input string in a database function to change it to a case-insensitive representation.- Angegeben von:
ignoreCase
in SchnittstelleAdapter
- Parameter:
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.- Gibt zurück:
- The wrapped input string, so that the database evaluates the returned expression to a case-insensitive representation of the input.
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ignoreCaseInOrderBy
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) do not use the same SQL in ORDER BY and other clauses.- Angegeben von:
ignoreCaseInOrderBy
in SchnittstelleAdapter
- Parameter:
in
- The string whose case to ignore.- Gibt zurück:
- The string in a case that can be ignored.
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supportsNativeLimit
public boolean supportsNativeLimit()Returns whether the database can natively limit the size of the ResultSet of a query.- Angegeben von:
supportsNativeLimit
in SchnittstelleAdapter
- Gibt zurück:
- true if the database natively supports limiting the size of the resultset.
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supportsNativeOffset
public boolean supportsNativeOffset()Returns whether the database natively supports returning results starting at an offset position other than 0.- Angegeben von:
supportsNativeOffset
in SchnittstelleAdapter
- Gibt zurück:
- true if the database natively supports returning results starting at an offset position other than 0.
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generateLimits
This method is used to generate the database specific query extension to limit the number of record returned.- Angegeben von:
generateLimits
in SchnittstelleAdapter
- Parameter:
query
- The query to modifyoffset
- the offset Valuelimit
- the limit Value- Löst aus:
TorqueException
- if any error occurs when building the query
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escapeText
public boolean escapeText()This method is for the SqlExpression.quoteAndEscape rules. The rule is, any string in a SqlExpression with a BACKSLASH will either be changed to "\\" or left as "\".- Angegeben von:
escapeText
in SchnittstelleAdapter
- Gibt zurück:
- true if the database needs to escape text in SqlExpressions.
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useIlike
public boolean useIlike()Whether ILIKE should be used for case insensitive like clauses. As most databases do not use ILIKE, this implementation returns false. This behaviour may be overwritten in subclasses. -
useEscapeClauseForLike
public boolean useEscapeClauseForLike()Whether an escape clause in like should be used. Example : select * from AUTHOR where AUTHOR.NAME like '\_%' ESCAPE '\'; As most databases do not need the escape clause, this implementation always returnsfalse
. This behaviour can be overwritten in subclasses.- Angegeben von:
useEscapeClauseForLike
in SchnittstelleAdapter
- Gibt zurück:
- whether the escape clause should be appended or not.
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useMinusForExcept
public boolean useMinusForExcept()Whether to use the MINUS operator instead of the EXCEPT operator. As most databases do not need to replace the EXCEPT operator by the MINUS operator, this implementation always returnsfalse
. This behaviour can be overwritten in subclasses.- Angegeben von:
useMinusForExcept
in SchnittstelleAdapter
- Gibt zurück:
- whether to use the MINUS operator instead of the EXCEPT operator.
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useGetGeneratedKeys
public boolean useGetGeneratedKeys()whether Statement#getGeneratedKeys() should be used.- Angegeben von:
useGetGeneratedKeys
in SchnittstelleAdapter
- Gibt zurück:
- a
boolean
value
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setCapabilities
Update static capabilities of the adapter with actual readings based on the JDBC meta-data- Angegeben von:
setCapabilities
in SchnittstelleAdapter
- Parameter:
dmd
- database meta data- Löst aus:
SQLException
- if there are problems getting the JDBC meta data
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