net.digger.db

Class H2Helper

java.lang.Object

net.digger.db.H2Helper

public class H2Helper
extends Object

Utility class for H2 Database. Provides table versioning and reduces boilerplate code.

Author:

walton

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	H2Helper.PrepareCallback Callback used for working with PreparedStatement before executing query.
static interface	H2Helper.ResultCallback<T> Callback used for processing query ResultSet.
static interface	H2Helper.UpgradeCallback Callback used for creating and upgrading database tables.

Constructor Summary

Constructors

Constructor and Description
H2Helper(Path datafile) Create instance of H2DB using given database, and initialize table version table.

Method Summary

Modifier and Type	Method and Description
Connection	connect() Opens and returns a connection to the database as user "sa".
Connection	connect(String user, String password) Opens and returns a connection to the database as given user.
int[]	doBatchUpdate(Connection conn, String sql, H2Helper.PrepareCallback pc) Perform database batch update transaction, doing PreparedStatement setup and cleanup.
int[]	doBatchUpdate(String sql, H2Helper.PrepareCallback pc) Perform database batch update transaction, doing Connection and PreparedStatement setup and cleanup.
<T> T	doQuery(Connection conn, String sql, H2Helper.PrepareCallback pc, H2Helper.ResultCallback<T> rc) Perform database query, doing PreparedStatement and ResultSet setup and cleanup.
<T> T	doQuery(String sql, H2Helper.PrepareCallback pc, H2Helper.ResultCallback<T> rc) Perform database query, doing Connection, PreparedStatement and ResultSet setup and cleanup.
int	doUpdate(Connection conn, String sql, H2Helper.PrepareCallback pc) Perform database update, doing PreparedStatement setup and cleanup.
int	doUpdate(String sql, H2Helper.PrepareCallback pc) Perform database update, doing Connection and PreparedStatement setup and cleanup.
void	initTable(String name, int version, H2Helper.UpgradeCallback upgrade) Checks the version of the given table against the given version, and calls the upgrade callback if necessary.

Methods inherited from class java.lang.Object

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

Constructor Detail

H2Helper

public H2Helper(Path datafile)
         throws IOException,
                ClassNotFoundException,
                SQLException

Create instance of H2DB using given database, and initialize table version table.

Parameters:

datafile - Path to database.

Throws:

IOException - If error creating database directory.

ClassNotFoundException - If error loading database driver.

SQLException - If database error occurs.

Method Detail

connect

public Connection connect()
                   throws SQLException

Opens and returns a connection to the database as user "sa".

Returns:

Database connection.

Throws:

SQLException - If database error occurs.

connect

public Connection connect(String user,
                          String password)
                   throws SQLException

Opens and returns a connection to the database as given user.

Parameters:

user - Username for connection.

password - Password for connection.

Returns:

Database connection.

Throws:

SQLException - If database error occurs.

initTable

public void initTable(String name,
                      int version,
                      H2Helper.UpgradeCallback upgrade)
               throws SQLException

Checks the version of the given table against the given version, and calls the upgrade callback if necessary. After successful completion of the upgrade callback, updates table to the given version.

Parameters:

name - Name of table to check.

version - Desired table version.

upgrade - Callback to use if the current version is less than desired version.

Throws:

SQLException - If database error occurs.

doQuery

public <T> T doQuery(String sql,
                     H2Helper.PrepareCallback pc,
                     H2Helper.ResultCallback<T> rc)
              throws SQLException

Perform database query, doing Connection, PreparedStatement and ResultSet setup and cleanup.

Type Parameters:

T - Type of data object to return.

Parameters:

sql - Query SQL.

pc - Callback for preparing query. Can be null.

rc - Callback for processing result set.

Returns:

Return value from rc.

Throws:

SQLException - If database error occurs.

doQuery

public <T> T doQuery(Connection conn,
                     String sql,
                     H2Helper.PrepareCallback pc,
                     H2Helper.ResultCallback<T> rc)
              throws SQLException

Perform database query, doing PreparedStatement and ResultSet setup and cleanup.

Type Parameters:

T - Type of data object to return.

Parameters:

conn - Database connection to use.

sql - Query SQL.

pc - Callback for preparing query. Can be null.

rc - Callback for processing result set.

Returns:

Return value from rc.

Throws:

SQLException - If database error occurs.

doUpdate

public int doUpdate(String sql,
                    H2Helper.PrepareCallback pc)
             throws SQLException

Perform database update, doing Connection and PreparedStatement setup and cleanup.

Parameters:

sql - Update SQL.

pc - Callback for preparing update. Can be null.

Returns:

Row count.

Throws:

SQLException - If database error occurs.

doUpdate

public int doUpdate(Connection conn,
                    String sql,
                    H2Helper.PrepareCallback pc)
             throws SQLException

Perform database update, doing PreparedStatement setup and cleanup.

Parameters:

conn - Database connection to use.

sql - Update SQL.

pc - Callback for preparing update. Can be null.

Returns:

Row count.

Throws:

SQLException - If database error occurs.

doBatchUpdate

public int[] doBatchUpdate(String sql,
                           H2Helper.PrepareCallback pc)
                    throws SQLException

Perform database batch update transaction, doing Connection and PreparedStatement setup and cleanup.

Parameters:

sql - Batch update SQL.

pc - Callback for preparing batch update. Can be null.

Returns:

Array of row counts.

Throws:

SQLException - If database error occurs.

doBatchUpdate

public int[] doBatchUpdate(Connection conn,
                           String sql,
                           H2Helper.PrepareCallback pc)
                    throws SQLException

Perform database batch update transaction, doing PreparedStatement setup and cleanup.

Parameters:

conn - Database connection to use.

sql - Batch update SQL.

pc - Callback for preparing batch update. Can be null.

Returns:

Array of row counts.

Throws:

SQLException - If database error occurs.