ch.agent.crnickl.jdbc
Class JDBCDatabaseMethods

java.lang.Object
  ch.agent.crnickl.impl.DatabaseMethodsImpl
      ch.agent.crnickl.jdbc.JDBCDatabaseMethods

All Implemented Interfaces:

ch.agent.crnickl.impl.DatabaseMethods, ch.agent.crnickl.impl.PermissionChecker

Direct Known Subclasses:

AccessMethodsForAny, AccessMethodsForNumber, ReadMethodsForChroniclesAndSeries, ReadMethodsForProperty, ReadMethodsForSchema, ReadMethodsForValueType, WriteMethodsForValueType

public class JDBCDatabaseMethods
extends ch.agent.crnickl.impl.DatabaseMethodsImpl

A JDBCDatabaseMethods object provides support for prepared statements. It is meant as base class for actual access methods. All database accesses should be bracketed between one of the open and the close method.

Author:

Jean-Paul Vetterli

Constructor Summary

JDBCDatabaseMethods()

Method Summary

PreparedStatement	close(PreparedStatement stmt) Close the prepared statement.
ch.agent.crnickl.api.DBObjectId	executeAndGetNewId(PreparedStatement stmt) Execute a prepared statement of the "insertion" type and return the generated id.
protected int	getId(ch.agent.crnickl.api.DBObject dBObject) Return the internal ID of a database object.
int	getId(ch.agent.crnickl.api.Surrogate surrogate) Extract the internal ID of a database object from its surrogate.
int	getIdOrZero(ch.agent.crnickl.api.DBObject dBObject) Return the internal ID of a database object or 0 if the object is null or is in construction.
ch.agent.crnickl.api.Surrogate	makeSurrogate(ch.agent.crnickl.api.Database db, ch.agent.crnickl.api.DBObjectType dot, int id) Create a surrogate for a database object.
PreparedStatement	open(String sql, ch.agent.crnickl.api.Database database, PreparedStatement stmt) Return a valid prepared statement for the SQL code specified.
PreparedStatement	open(String sql, ch.agent.crnickl.api.DBObject dBObject, PreparedStatement stmt) Return a valid prepared statement for the SQL code specified.
PreparedStatement	open(String sql, ch.agent.crnickl.api.Surrogate surrogate, PreparedStatement stmt) Return a valid prepared statement for the SQL code specified.

Methods inherited from class ch.agent.crnickl.impl.DatabaseMethodsImpl

check, check, check, check, checkIntegrity, makeSurrogate, makeSurrogate

Methods inherited from class java.lang.Object

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

Constructor Detail

JDBCDatabaseMethods

public JDBCDatabaseMethods()

Method Detail

getIdOrZero

public int getIdOrZero(ch.agent.crnickl.api.DBObject dBObject)

Return the internal ID of a database object or 0 if the object is null or is in construction. The internal ID is not exposed to clients.

This method is for use inside the JDBC implementation and its argument must have a DBObjectId implemented by JDBCObjectId.

Parameters:

dBObject - a database object or null

Returns:

a non negative integer

getId

protected int getId(ch.agent.crnickl.api.DBObject dBObject)

Return the internal ID of a database object. The internal ID is not exposed to clients.

This method is for use inside the JDBC implementation and its argument must have a DBObjectId implemented by JDBCObjectId.

Parameters:

dBObject - a database object

Returns:

a positive integer

getId

public int getId(ch.agent.crnickl.api.Surrogate surrogate)

Extract the internal ID of a database object from its surrogate. The internal ID is not exposed to clients.

This method is for use inside the JDBC implementation and its argument must have a DBObjectId implemented by JDBCObjectId.

Parameters:

surrogate - the surrogate of a database object

Returns:

a positive integer

makeSurrogate

public ch.agent.crnickl.api.Surrogate makeSurrogate(ch.agent.crnickl.api.Database db,
                                                    ch.agent.crnickl.api.DBObjectType dot,
                                                    int id)

Create a surrogate for a database object.

Parameters:

db - the database of the object

dot - the type of the object

id - the internal ID of the database object

Returns:

a surrogate

executeAndGetNewId

public ch.agent.crnickl.api.DBObjectId executeAndGetNewId(PreparedStatement stmt)
                                                   throws ch.agent.crnickl.T2DBException,
                                                          SQLException

Execute a prepared statement of the "insertion" type and return the generated id.

Parameters:

stmt - a prepared statement

Returns:

a generated id

Throws:

ch.agent.crnickl.T2DBException

SQLException

open

public PreparedStatement open(String sql,
                              ch.agent.crnickl.api.Database database,
                              PreparedStatement stmt)
                       throws ch.agent.crnickl.T2DBException

Return a valid prepared statement for the SQL code specified. The statement is prepared using the connection embedded in the database parameter. To avoid preparing a new statement again and again a statement can be passed as an argument. This statement will be returned if it is not null and if its connection is equal to the connection embedded in the mentioned parameter.

Parameters:

sql - a string in SQL syntax

database - a database

stmt - a prepared statement

Returns:

a prepared statement

Throws:

ch.agent.crnickl.T2DBException

open

public PreparedStatement open(String sql,
                              ch.agent.crnickl.api.DBObject dBObject,
                              PreparedStatement stmt)
                       throws ch.agent.crnickl.T2DBException

Return a valid prepared statement for the SQL code specified. The statement is prepared using the connection embedded in the dBObject parameter. To avoid preparing a new statement again and again a statement can be passed as an argument. This statement will be returned if it is not null and if its connection is equal to connection embedded in the mentioned parameter.

Parameters:

sql - a string in SQL syntax

dBObject - a database object

stmt - a prepared statement

Returns:

a prepared statement

Throws:

ch.agent.crnickl.T2DBException

open

public PreparedStatement open(String sql,
                              ch.agent.crnickl.api.Surrogate surrogate,
                              PreparedStatement stmt)
                       throws ch.agent.crnickl.T2DBException

Return a valid prepared statement for the SQL code specified. The statement is prepared using the connection embedded in the surrogate parameter. To avoid preparing a new statement again and again a statement can be passed as an argument. This statement will be returned if it is not null and if its connection is equal to connection embedded in the mentioned parameter.

Parameters:

sql - a string in SQL syntax

surrogate - a surrogate

stmt - a prepared statement

Returns:

a prepared statement

Throws:

ch.agent.crnickl.T2DBException

close

public PreparedStatement close(PreparedStatement stmt)
                        throws ch.agent.crnickl.T2DBException

Close the prepared statement. This implementation actually closes the statement and returns null. Possibly, a future implementation could decide not to close the statement and to return it to the client. For this reason it is meaningful for clients to cache the statement for reuse, with a possible positive effect on performance.

Parameters:

stmt - a prepared statement

Returns:

the prepared statement, set to null

Throws:

ch.agent.crnickl.T2DBException