org.geotools.data.jdbc
Class DefaultSQLBuilder

java.lang.Object
  org.geotools.data.jdbc.DefaultSQLBuilder

All Implemented Interfaces:

SQLBuilder

Direct Known Subclasses:

BBOXSQLBuilder, DB2SQLBuilder, GeometrylessSQLBuilder, HsqlSQLBuilder, LocationsXYSQLBuilder, MySQLSQLBuilder, PostgisSQLBuilder

public class DefaultSQLBuilder

extends java.lang.Object

implements SQLBuilder

Builds a complete SQL query to select the specified attributes for the specified feature type, using a specified filter to generate a WHERE clause.

The actual WHERE clause is generated by the SQLEncoder class or appropriate subclass for a particular database. If a specific encoder is to be used, it must be specified to the constructor for this class.

In order to implement the functionality of the application-specified Filter, this is split into a 'preQueryFilter' which can be incorporated into the SQL query itself and a 'postQueryFilter. The encoder capabilities are used to determine how much of the function can be performed by the database directly and how much has to be performed on the result set.

Author:

Sean Geoghegan, Defence Science and Technology Organisation.

Field Summary

protected SQLEncoder

encoder

Constructor Summary

DefaultSQLBuilder()
Constructs an instance of this class with a default SQLEncoder

DefaultSQLBuilder(SQLEncoder encoder)
Constructs an instance of this class using the encoder class specified.

Method Summary

java.lang.String	buildSQLQuery(java.lang.String typeName, FIDMapper mapper, AttributeType[] attrTypes, Filter filter) Constructs the full SQL SELECT statement for the supplied Filter.
Filter	getPostQueryFilter(Filter filter) Return the postQueryFilter that must be applied to the database query result set.
Filter	getPreQueryFilter(Filter filter) Return the preQueryFilter that can be used to generate the WHERE clause.
void	sqlColumns(java.lang.StringBuffer sql, FIDMapper mapper, AttributeType[] attributes) Appends the names of the columns to be selected.
void	sqlFrom(java.lang.StringBuffer sql, java.lang.String typeName) Constructs the FROM clause for a featureType sql: FROM typeName
void	sqlGeometryColumn(java.lang.StringBuffer sql, AttributeType geomAttribute) Generates the select column specification for a geometry column.
void	sqlWhere(java.lang.StringBuffer sql, Filter preFilter) Constructs WHERE clause, if needed, for FILTER.

Methods inherited from class java.lang.Object

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

Field Detail

encoder

protected SQLEncoder encoder

Constructor Detail

DefaultSQLBuilder

public DefaultSQLBuilder()

Constructs an instance of this class with a default SQLEncoder

DefaultSQLBuilder

public DefaultSQLBuilder(SQLEncoder encoder)

Constructs an instance of this class using the encoder class specified. This will typically be from the getSqlBuilder method of a JDBCDataStore subclass

Parameters:

encoder - the specific encoder to be used.

Method Detail

getPostQueryFilter

public Filter getPostQueryFilter(Filter filter)

Return the postQueryFilter that must be applied to the database query result set.

Specified by:

getPostQueryFilter in interface SQLBuilder

Parameters:

filter - the application filter which must be applied

Returns:

the filter representing the functionality that must be performed on the result set.

getPreQueryFilter

public Filter getPreQueryFilter(Filter filter)

Return the preQueryFilter that can be used to generate the WHERE clause.

Specified by:

getPreQueryFilter in interface SQLBuilder

Parameters:

filter - the application filter which must be applied

Returns:

the filter representing the functionality that can be performed by the database.

sqlFrom

public void sqlFrom(java.lang.StringBuffer sql,
                    java.lang.String typeName)

Constructs the FROM clause for a featureType

sql: FROM typeName

Specified by:

sqlFrom in interface SQLBuilder

Parameters:

sql - the StringBuffer that the WHERE clause should be appended to

typeName - the name of the table (feature type) to be queried

sqlWhere

public void sqlWhere(java.lang.StringBuffer sql,
                     Filter preFilter)
              throws SQLEncoderException

Constructs WHERE clause, if needed, for FILTER.

sql: WHERE filter encoding

Specified by:

sqlWhere in interface SQLBuilder

Parameters:

sql - The StringBuffer that the WHERE clause should be appended to

preFilter - The filter to be used by the encoder class to generate the WHERE clause

Throws:

SQLEncoderException - Not thrown here but may be thrown by the encoder

buildSQLQuery

public java.lang.String buildSQLQuery(java.lang.String typeName,
                                      FIDMapper mapper,
                                      AttributeType[] attrTypes,
                                      Filter filter)
                               throws SQLEncoderException

Constructs the full SQL SELECT statement for the supplied Filter.

The statement is constructed by concatenating the SELECT column list, FROM table specification and WHERE clause appropriate to the supplied Filter.

Specified by:

buildSQLQuery in interface SQLBuilder

Parameters:

typeName - The name of the table (feature type) to be queried

mapper - FIDMapper to identify the FID columns in the table

attrTypes - The specific attribute columns to be selected

filter - The Filter that will be used by the encoder to construct the WHERE clause

Returns:

The fully formed SQL SELECT statement

Throws:

SQLEncoderException - Not thrown by this method but may be thrown by the encoder class

sqlColumns

public void sqlColumns(java.lang.StringBuffer sql,
                       FIDMapper mapper,
                       AttributeType[] attributes)

Appends the names of the columns to be selected.

sqlGeometryColumn is invoked for any special handling for geometry columns.

Specified by:

sqlColumns in interface SQLBuilder

Parameters:

sql - StringBuffer to be appended to

mapper - FIDMapper to provide the name(s) of the FID columns

attributes - Array of columns to be selected

See Also:

postgisDataStore.SQLBuilder#sqlColumns(java.lang.StringBuffer, postgisDataStore.FIDMapper.FIDMapper, org.geotools.feature.AttributeType[])

sqlGeometryColumn

public void sqlGeometryColumn(java.lang.StringBuffer sql,
                              AttributeType geomAttribute)

Generates the select column specification for a geometry column.

This should typically be overridden in the subclass to return a meaningful value that the attribute i/o handler can process.

Parameters:

sql - A StringBuffer that the column specification can be appended to

geomAttribute - An AttributeType for a geometry attribute