uk.ac.ed.epcc.webapp.jdbc

Class DefaultDataBaseService

java.lang.Object

uk.ac.ed.epcc.webapp.jdbc.DefaultDataBaseService

All Implemented Interfaces:

AppContextCleanup, AppContextService<DatabaseService>, Contexed, CloseRegistry, DatabaseService

Direct Known Subclasses:

JNDIDatabaseService

public class DefaultDataBaseService
extends java.lang.Object
implements DatabaseService

Default implementation of the DatabaseService This gets connection parameters from the ConfigService but this is only queried at the point where a database connection is required. The following config parameters are read:

• db_name[.tag] connection url
• db_type[.tag] connection type [mysql or postgres]
• db_name[.tag] connection url
• transaction.isolation_level isolationlevel to use for transactions

Field Summary

Fields

Modifier and Type	Field and Description
protected static java.lang.String	POSTGRESQL_TYPE
static Feature	TRANSACTIONS_FEATURE
static Feature	TRANSACTIONS_ROLLBACK_TRANSIENT_ERRORS
static Feature	TRANSACTIONS_SERIALIZE_FEATURE

Fields inherited from interface uk.ac.ed.epcc.webapp.jdbc.DatabaseService

LOG_INSERT_FEATURE, LOG_QUERY_FEATURE, LOG_UPDATE, USE_SQL_DISTICT_FEATURE

Constructor Summary

Constructors

Constructor and Description
DefaultDataBaseService(AppContext ctx)

Method Summary

Modifier and Type	Method and Description
void	addClosable(java.lang.AutoCloseable c)
void	cleanup() AppContext is being closed.
void	closeRetainedClosables()
void	commitTransaction() flush changes since start of last commit.
java.util.Map<java.lang.String,java.lang.Object>	getConnectionAttributes() get a map of information about the connection
AppContext	getContext()
SQLContext	getSQLContext() get SQLContext using the default ConfigService
SQLContext	getSQLContext(java.lang.String tag) get alternative database SQLContext If the tag is null it returns the same SQLContext as DatabaseService.getSQLContext().
SQLContext	getSQLContext(java.lang.String tag, java.util.Properties props) returns a database connection for the application based on a set of Config Propertis
int	getTargetIsolationLevel()
java.lang.Class<DatabaseService>	getType() Returns the type of service the class should be registered under.
void	handleError(java.lang.String message, java.sql.SQLException e) Handle an unexpected database exception.
boolean	inTransaction() Are we already in a transaction
void	logError(java.lang.String message, java.sql.SQLException e) handle an SQLException directly.
protected SQLContext	makeSQLContext(java.lang.String tag, java.util.Properties props) default method for creating a SQLContext from InitParameters This method is only invoked the first time an AppContext needs a Connection to reduce overhead in static pages.
static int	parseLevel(java.lang.String name)
void	removeClosable(java.lang.AutoCloseable c)
void	rollbackTransaction() Abort changes since start or last commit
protected void	setSQLContext(SQLContext c) Set the database Connection.
void	startTransaction() Start a database transaction Transactions cannot be nested so use DatabaseService.inTransaction() if possible doubt.
void	stopTransaction() finish transaction (includes commit).
int	transactionStage() returns the number of times DatabaseService.commitTransaction() has been called since the last transaction start.

Methods inherited from class java.lang.Object

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

Field Detail

TRANSACTIONS_FEATURE

public static final Feature TRANSACTIONS_FEATURE

TRANSACTIONS_SERIALIZE_FEATURE

public static final Feature TRANSACTIONS_SERIALIZE_FEATURE

TRANSACTIONS_ROLLBACK_TRANSIENT_ERRORS

public static final Feature TRANSACTIONS_ROLLBACK_TRANSIENT_ERRORS

POSTGRESQL_TYPE

protected static final java.lang.String POSTGRESQL_TYPE

See Also:

Constant Field Values

Constructor Detail

DefaultDataBaseService

public DefaultDataBaseService(AppContext ctx)

Method Detail

getSQLContext

public final SQLContext getSQLContext()
                               throws java.sql.SQLException

Description copied from interface: DatabaseService

get SQLContext using the default ConfigService

Specified by:

getSQLContext in interface DatabaseService

Returns:

SQLContext to database

Throws:

java.sql.SQLException

getSQLContext

public final SQLContext getSQLContext(java.lang.String tag)
                               throws java.sql.SQLException

Description copied from interface: DatabaseService

get alternative database SQLContext If the tag is null it returns the same SQLContext as DatabaseService.getSQLContext().

Specified by:

getSQLContext in interface DatabaseService

Returns:

Connection to database

Throws:

java.sql.SQLException

getSQLContext

public SQLContext getSQLContext(java.lang.String tag,
                                java.util.Properties props)
                         throws java.sql.SQLException

returns a database connection for the application based on a set of Config Propertis

Specified by:

getSQLContext in interface DatabaseService

Returns:

A SQLContext

Throws:

java.sql.SQLException

setSQLContext

protected void setSQLContext(SQLContext c)
                      throws java.sql.SQLException

Set the database Connection. Should be called from sub-class constructor

Parameters:

c - the Connection to use

Throws:

java.sql.SQLException

makeSQLContext

protected SQLContext makeSQLContext(java.lang.String tag,
                                    java.util.Properties props)
                             throws java.sql.SQLException

default method for creating a SQLContext from InitParameters This method is only invoked the first time an AppContext needs a Connection to reduce overhead in static pages.

Returns:

A database Connection

Throws:

java.sql.SQLException

getContext

public AppContext getContext()

Specified by:

getContext in interface Contexed

cleanup

public void cleanup()

Description copied from interface: AppContextCleanup

AppContext is being closed. Only use this for cleanup that can't be handled by normal garbage collection or for state which is never returned by reference.

Specified by:

cleanup in interface AppContextCleanup

closeRetainedClosables

public void closeRetainedClosables()

Specified by:

closeRetainedClosables in interface CloseRegistry

getType

public java.lang.Class<DatabaseService> getType()

Description copied from interface: AppContextService

Returns the type of service the class should be registered under.

Specified by:

getType in interface AppContextService<DatabaseService>

Returns:

registration type

inTransaction

public boolean inTransaction()

Description copied from interface: DatabaseService

Are we already in a transaction

Specified by:

inTransaction in interface DatabaseService

Returns:

boolean

startTransaction

public void startTransaction()

Description copied from interface: DatabaseService

Start a database transaction Transactions cannot be nested so use DatabaseService.inTransaction() if possible doubt.

Specified by:

startTransaction in interface DatabaseService

getTargetIsolationLevel

public int getTargetIsolationLevel()

Returns:

rollbackTransaction

public void rollbackTransaction()

Description copied from interface: DatabaseService

Abort changes since start or last commit

Specified by:

rollbackTransaction in interface DatabaseService

commitTransaction

public void commitTransaction()

Description copied from interface: DatabaseService

flush changes since start of last commit. Unlike the commit method of a Connection this is a NOP if not in a transaction. Call before an operation that modifies external state as these won't roll-back. However probably better to defer the external state change using the CleanupService unless the transaction phases all make sense in their own right.

Specified by:

commitTransaction in interface DatabaseService

stopTransaction

public void stopTransaction()

Description copied from interface: DatabaseService

finish transaction (includes commit).

Specified by:

stopTransaction in interface DatabaseService

transactionStage

public int transactionStage()

Description copied from interface: DatabaseService

returns the number of times DatabaseService.commitTransaction() has been called since the last transaction start. If this returns 0 then a roll-back will return to the state at DatabaseService.startTransaction() if greater than zero there have been intermediate commits. To aid in testing the value is not reset to zero until the next call to DatabaseService.startTransaction()

Specified by:

transactionStage in interface DatabaseService

Returns:

int

handleError

public void handleError(java.lang.String message,
                        java.sql.SQLException e)
                 throws DataFault

Description copied from interface: DatabaseService

Handle an unexpected database exception. Most of the time this will just re-throw the exception wrapped in a DataFault however this also allow special handing of certain classes of error such as SQLTransientExceptions

Specified by:

handleError in interface DatabaseService

Throws:

DataFault

logError

public void logError(java.lang.String message,
                     java.sql.SQLException e)

Description copied from interface: DatabaseService

handle an SQLException directly. Normally this will just log the error however this also allow special handing of certain classes of error such as SQLTransientExceptions

Specified by:

logError in interface DatabaseService

parseLevel

public static int parseLevel(java.lang.String name)

addClosable

public void addClosable(java.lang.AutoCloseable c)

Specified by:

addClosable in interface CloseRegistry

removeClosable

public void removeClosable(java.lang.AutoCloseable c)

Specified by:

removeClosable in interface CloseRegistry

getConnectionAttributes

public java.util.Map<java.lang.String,java.lang.Object> getConnectionAttributes()
                                                                         throws java.lang.Exception

Description copied from interface: DatabaseService

get a map of information about the connection

Specified by:

getConnectionAttributes in interface DatabaseService

Returns:

Throws:

java.lang.Exception