org.geotools.graph.io.standard

Class DBReaderWriter

Object

AbstractReaderWriter

DBReaderWriter

All Implemented Interfaces:

GraphReaderWriter

public abstract class DBReaderWriter
extends AbstractReaderWriter

An implementation of GraphReaderWriter used for reading and writing graph objects to and from a database.

Upon reading, the database is queried using the getQuery() template method, and a representation of the objects to be modelled by the graph are returned through a standard ResultSet. From each tuple in the result set, the object is recreated via the template method readInternal(ResultSet). The object is then passed to an underlying graph generator and the graph components used to model the object are constructed.

Upon writing, the graph is read component by component based on set properties. If the NODES property is set, nodes will be written. If the EDGES property is set, edges will be written as well. As each component is processed, it is passed to the repspective template methods writeNode(Statement,Node) and writeEdge(Statement,Edge). The methods then execute a statement to create the database representation of the graph component.

Author:

Justin Deoliveira, Refractions Research Inc, jdeolive@refractions.net

Field Summary

Fields

Modifier and Type	Field and Description
static String	DBNAME Database name key *
static String	DRIVERCLASS JDBC driver class name key *
static String	DRIVERURL JDBC driver url *
static String	PORT Database port key *
static String	SERVER Database server key *
static String	TABLENAME Table key *
static String	USERNAME User name key *

Fields inherited from class AbstractReaderWriter

BUILDER, EDGES, GENERATOR, NODES

Constructor Summary

Constructors

Constructor and Description
DBReaderWriter()

Method Summary

Modifier and Type	Method and Description
protected Connection	getConnection() Opens a connection to the database, based on set properties.
protected abstract String	getQuery() Template method which returns the query to execute in order to read a graph from the database.
Graph	read() Performs a graph read by querying the database and processing each tuple returned in the query.
protected abstract Object	readInternal(ResultSet rs) Template method used to create the object represented by a tuple returned by the database query.
void	write(Graph g) Performs a write on the graph out to the database.
protected void	writeEdge(Statement st, Edge edge) Template method used to write an edge into the database.
protected void	writeNode(Statement st, Node node) Template method used to write a node into the database.

Methods inherited from class AbstractReaderWriter

getProperty, setProperty, setProperty

Methods inherited from class Object

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

Field Detail

DRIVERCLASS

public static final String DRIVERCLASS

JDBC driver class name key *

See Also:

Constant Field Values

DRIVERURL

public static final String DRIVERURL

JDBC driver url *

See Also:

Constant Field Values

SERVER

public static final String SERVER

Database server key *

See Also:

Constant Field Values

PORT

public static final String PORT

Database port key *

See Also:

Constant Field Values

DBNAME

public static final String DBNAME

Database name key *

See Also:

Constant Field Values

USERNAME

public static final String USERNAME

User name key *

See Also:

Constant Field Values

TABLENAME

public static final String TABLENAME

Table key *

See Also:

Constant Field Values

Constructor Detail

DBReaderWriter

public DBReaderWriter()

Method Detail

read

public Graph read()
           throws Exception

Performs a graph read by querying the database and processing each tuple returned in the query. As each tuple is processed, the graph components represented by the tuple are created by an underlying GraphGenerator.

Returns:

The represented graph.

Throws:

Exception

See Also:

GraphReaderWriter.read()

write

public void write(Graph g)
           throws Exception

Performs a write on the graph out to the database. If the NODES property is set, the nodes of the graph will be written, and if the EDGES property is set, the edges of the graph will be written.

* @see GraphGenerator#write()

Parameters:

g - The graph to be

Throws:

Exception

getConnection

protected Connection getConnection()
                            throws Exception

Opens a connection to the database, based on set properties.

Returns:

Connection to the database.

Throws:

Exception

writeNode

protected void writeNode(Statement st,
                         Node node)

Template method used to write a node into the database.

Parameters:

st - Statement used to execute write statement.

node - Node to write.

writeEdge

protected void writeEdge(Statement st,
                         Edge edge)

Template method used to write an edge into the database.

Parameters:

st - Statement used to execute write statement.

edge - Edge to write.

getQuery

protected abstract String getQuery()

Template method which returns the query to execute in order to read a graph from the database.

Returns:

SQL query.

readInternal

protected abstract Object readInternal(ResultSet rs)
                                throws Exception

Template method used to create the object represented by a tuple returned by the database query.

Parameters:

rs - ResultSet of query.

Returns:

Object represented by current tuple of result set.

Throws:

Exception