prajna.structure.accessor

Class JdbcAccessor

java.lang.Object

prajna.structure.AbstractDataAccessor<DataRecord,DataRecord>

prajna.structure.accessor.RecordAccessor

prajna.structure.accessor.JdbcAccessor

All Implemented Interfaces:

DataAccessor<DataRecord,DataRecord>

public class JdbcAccessor
extends RecordAccessor

Semantic Data Accessor which queries data from a JDBC-enabled database. The connection may be provided directly, or the connection parameters may be specified in the initialization parameters. This class constructs SQL queries and retrieves the data directly from the database.

Author:

Edward Swing

Constructor Summary

Constructors

Constructor and Description
JdbcAccessor() Create a new JdbcAccessor.
JdbcAccessor(java.sql.Connection connection) Create a new JdbcAccessor using the given connection

Method Summary

Methods

Modifier and Type	Method and Description
boolean	extendGraph(java.lang.String graphName, Graph<DataRecord,DataRecord> graph, DataRecord node) Extend the given graph around the specified node.
boolean	extendTree(java.lang.String treeName, Tree<DataRecord> tree, DataRecord node) Extend the given tree around the specified node.
protected java.util.Set<DataRecord>	retrieveRecords(DataTemplate template) Retrieve a set of data records for a particular DataTemplate.
void	setConnection(java.sql.Connection connection) Set the connection used by this JdbcAccessor
void	setInitParameters(java.util.Map<java.lang.String,java.lang.String> parameters) Set any initialization parameters required by this data accessor.
void	setQuery(java.lang.String queryString) Set the query string used to retrieve records.

Methods inherited from class prajna.structure.accessor.RecordAccessor

addFieldHandler, addToGraph, addToTree, createReferenceNode, getDataset, getFieldHandler, getGraph, getGrid, getMaxRecords, getReasoner, getStructureReasoners, getTree, setMaxRecords, setReasoner, setReasoner

Methods inherited from class prajna.structure.AbstractDataAccessor

addStructure, addTemplate, getDatasetNames, getGraphNames, getGridNames, getSpec, getStructureType, getTemplate, getTemplateNames, getTreeNames, setConfig, setConfigFile, setConfigFile

Methods inherited from class java.lang.Object

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

Constructor Detail

JdbcAccessor

public JdbcAccessor()

Create a new JdbcAccessor. Driver, URL, user name and password should be provided by the setInitParameters method.

JdbcAccessor

public JdbcAccessor(java.sql.Connection connection)

Create a new JdbcAccessor using the given connection

Parameters:

connection - the connection for the JSQL queries

Method Detail

extendGraph

public boolean extendGraph(java.lang.String graphName,
                  Graph<DataRecord,DataRecord> graph,
                  DataRecord node)

Extend the given graph around the specified node.

Specified by:

extendGraph in interface DataAccessor<DataRecord,DataRecord>

Overrides:

extendGraph in class RecordAccessor

Parameters:

graphName - The name of the graph

graph - The graph to extend

node - The node to use as an extension point.

Returns:

true if more data was added to the graph, false otherwise.

extendTree

public boolean extendTree(java.lang.String treeName,
                 Tree<DataRecord> tree,
                 DataRecord node)

Extend the given tree around the specified node. This method adds any children which are not already part of the tree.

Specified by:

extendTree in interface DataAccessor<DataRecord,DataRecord>

Overrides:

extendTree in class RecordAccessor

Parameters:

treeName - The name of the graph

tree - The graph to extend

node - The node to use as an extension point.

Returns:

true if more data was added to the tree, false otherwise.

retrieveRecords

protected java.util.Set<DataRecord> retrieveRecords(DataTemplate template)

Retrieve a set of data records for a particular DataTemplate. This method is used by the various getStructure methods. The method constructs an SQL query from the provided template, queries the database, and parses the results into DataRecords. Each row is parsed into a separate DataRecord.

Specified by:

retrieveRecords in class RecordAccessor

Parameters:

template - The data template specifying field mappings and descriptions

Returns:

the set of DataRecords for the template

Throws:

java.lang.IllegalStateException - if the connection has not been set.

setConnection

public void setConnection(java.sql.Connection connection)

Set the connection used by this JdbcAccessor

Parameters:

connection - the connection for the JSQL queries

setInitParameters

public void setInitParameters(java.util.Map<java.lang.String,java.lang.String> parameters)

Set any initialization parameters required by this data accessor. The connection parameters may be specified. The keys for the connection parameters are dbDriver, dbUrl, dbUser and dbPass.

Parameters:

parameters - a map of initialization parameters

setQuery

public void setQuery(java.lang.String queryString)

Set the query string used to retrieve records. This method should transform the query string into a format which the accessor can parse. The query string supports a query of the form field=value.

Specified by:

setQuery in class AbstractDataAccessor<DataRecord,DataRecord>

Parameters:

queryString - the query string