Package org.h2gis.geotools

Class H2GISDialect

  • public class H2GISDialect
extends BasicSQLDialect
    jdbc-h2gis is an extension to connect H2GIS a spatial library that brings spatial support to the H2 Java database.

    H2GISDialect for H2GIS database.

    Author:
    Erwan Bocher

    • Constructor Detail

    • Method Detail

      • isAggregatedSortSupported

        public boolean isAggregatedSortSupported​(String function)
        Description copied from class: SQLDialect
        Returns true if this dialect supports sorting together with the given aggregation function.
        Overrides:
        isAggregatedSortSupported in class SQLDialect

      • isEstimatedExtentsEnabled

        public boolean isEstimatedExtentsEnabled()
        true is the dialect uses the ST_EstimatedExtent function to compute the envelope of the table
        Returns:

      • setEstimatedExtentsEnabled

        public void setEstimatedExtentsEnabled​(boolean estimatedExtentsEnabled)
        Set to true to use the ST_EstimatedExtent function
        Parameters:
        estimatedExtentsEnabled - True to use the ST_EstimatedExtent function

      • isFunctionEncodingEnabled

        public boolean isFunctionEncodingEnabled()
        True if the function encoding is enabled, false otherwise.
        Returns:
        True if the function encoding is enabled, false otherwise.

      • initializeConnection

        public void initializeConnection​(Connection cx)
                          throws SQLException
        Description copied from class: SQLDialect
        Initializes a newly created database connection.

        Subclasses should override this method if there is some additional action that needs to be taken when a new connection to the database is created. The default implementation does nothing.

        Overrides:
        initializeConnection in class SQLDialect
        Parameters:
        cx - The new database connection.
        Throws:
        SQLException

      • includeTable

        public boolean includeTable​(String schemaName,
                            String tableName,
                            Connection cx)
        Description copied from class: SQLDialect
        Determines if the specified table should be included in those published by the datastore.

        This method returns true if the table should be published as a feature type, otherwise it returns false. Subclasses should override this method, this default implementation returns true.

        A database connection is provided to the dialect but it should not be closed. However any statements objects or result sets that are instantiated from it must be closed.

        Overrides:
        includeTable in class SQLDialect
        Parameters:
        schemaName - The schema of the table, might be null..
        tableName - The name of the table.
        cx - Database connection.

      • encodeGeometryColumn

        public void encodeGeometryColumn​(GeometryDescriptor gatt,
                                 String prefix,
                                 int srid,
                                 Hints hints,
                                 StringBuffer sql)
        Description copied from class: SQLDialect
        Encodes the name of a geometry column in a SELECT statement.

        This method should wrap the column name in any functions that are used to retrieve its value. For instance, often it is necessary to use the function asText, or asWKB when fetching a geometry.

        This method must also be sure to properly encode the name of the column with the SQLDialect.encodeColumnName(String, String, StringBuffer) function.

        Example: 

           
   sql.append( "asText(" );
   column( gatt.getLocalName(), sql );
   sql.append( ")" );
        Overrides:
        encodeGeometryColumn in class SQLDialect

      • encodeGeometryEnvelope

        public void encodeGeometryEnvelope​(String tableName,
                                   String geometryColumn,
                                   StringBuffer sql)
        Description copied from class: SQLDialect
        Encodes the spatial extent function of a geometry column in a SELECT statement.

        This method must also be sure to properly encode the name of the column with the #encodeColumnName(String, StringBuffer) function.

        Specified by:
        encodeGeometryEnvelope in class SQLDialect

      • decodeGeometryEnvelope

        public Envelope decodeGeometryEnvelope​(ResultSet rs,
                                       int column,
                                       Connection cx)
                                throws SQLException
        Description copied from class: SQLDialect
        Decodes the result of a spatial extent function in a SELECT statement.

        This method is given direct access to a result set. The column parameter is the index into the result set which contains the spatial extent value. The query for this value is build with the SQLDialect.encodeGeometryEnvelope(String, String, StringBuffer) method.

        This method must not read any other objects from the result set other then the one referenced by column.

        Specified by:
        decodeGeometryEnvelope in class SQLDialect
        Parameters:
        rs - A result set
        column - Index into the result set which points at the spatial extent value.
        cx - The database connection.
        Throws:
        SQLException

      • getGeometrySRID

        public Integer getGeometrySRID​(String schemaName,
                               String tableName,
                               String columnName,
                               Connection cx)
                        throws SQLException
        Description copied from class: SQLDialect
        Returns the spatial reference system identifier (srid) for a particular geometry column.

        This method is given a direct connection to the database. The connection must not be closed. However any statements or result sets instantiated from the connection must be closed.

        In the event that the srid cannot be determined, this method should return null .

        Overrides:
        getGeometrySRID in class SQLDialect
        Parameters:
        schemaName - The database schema, could be null.
        tableName - The table, never null.
        columnName - The column name, never null
        cx - The database connection.
        Throws:
        SQLException

      • getGeometryDimension

        public int getGeometryDimension​(String schemaName,
                                String tableName,
                                String columnName,
                                Connection cx)
                         throws SQLException
        Description copied from class: SQLDialect
        Returns the dimension of the coordinates in the geometry. Defaults to 2, subclasses can override it.

        This method is given a direct connection to the database. The connection must not be closed. However any statements or result sets instantiated from the connection must be closed.

        In the event that the dimension cannot be determined, this method should return 2

        Overrides:
        getGeometryDimension in class SQLDialect
        Parameters:
        schemaName - The database schema, could be null.
        tableName - The table, never null.
        columnName - The column name, never null
        cx - The database connection.
        Throws:
        SQLException

      • getSequenceForColumn

        public String getSequenceForColumn​(String schemaName,
                                   String tableName,
                                   String columnName,
                                   Connection cx)
                            throws SQLException
        Description copied from class: SQLDialect
        Determines the name of the sequence (if any) which is used to increment generate values for a table column.

        This method should return null if no such sequence exists.

        This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

        Overrides:
        getSequenceForColumn in class SQLDialect
        Parameters:
        schemaName - The schema name, this might be null.
        tableName - The table name.
        columnName - The column name.
        cx - The database connection.
        Throws:
        SQLException

      • getNextSequenceValue

        public Object getNextSequenceValue​(String schemaName,
                                   String sequenceName,
                                   Connection cx)
                            throws SQLException
        Description copied from class: SQLDialect
        Obtains the next value of a sequence, incrementing the sequence to the next state in the process.

        Implementations should determine the next value of a column for which values are automatically generated by the database.

        This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

        Implementations should handle the case where schemaName is null.

        Overrides:
        getNextSequenceValue in class SQLDialect
        Parameters:
        schemaName - The schema name, this might be null.
        sequenceName - The name of the sequence.
        cx - The database connection.
        Returns:
        The next value of the sequence, or null.
        Throws:
        SQLException

      • getLastAutoGeneratedValue

        public Object getLastAutoGeneratedValue​(String schemaName,
                                        String tableName,
                                        String columnName,
                                        Connection cx)
                                 throws SQLException
        Description copied from class: SQLDialect
        Obtains the last value of an auto generated column.

        This method is only called when SQLDialect.lookupGeneratedValuesPostInsert() returns true. Implementations should determine the previous value of a column for which was automatically generated by the database.

        This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

        Implementations should handle the case where schemaName is null.

        Overrides:
        getLastAutoGeneratedValue in class SQLDialect
        Parameters:
        schemaName - The schema name, this might be null.
        tableName - The name of the table.
        columnName - The column.
        cx - The database connection.
        Returns:
        The previous value of the column, or null.
        Throws:
        SQLException

      • registerClassToSqlMappings

        public void registerClassToSqlMappings​(Map<Class<?>,​Integer> mappings)
        Description copied from class: SQLDialect
        Registers the java type to sql type mappings that the datastore uses when reading and writing objects to and from the database. *

        Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation. This implementation provides the following mappings:

        Overrides:
        registerClassToSqlMappings in class SQLDialect

      • registerSqlTypeNameToClassMappings

        public void registerSqlTypeNameToClassMappings​(Map<String,​Class<?>> mappings)
        Description copied from class: SQLDialect
        Registers the sql type name to java type mappings that the dialect uses when reading and writing objects to and from the database.

        Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation. This implementation provides the following mappings:

        Overrides:
        registerSqlTypeNameToClassMappings in class SQLDialect

      • registerSqlTypeToSqlTypeNameOverrides

        public void registerSqlTypeToSqlTypeNameOverrides​(Map<Integer,​String> overrides)
        Description copied from class: SQLDialect
        Registers any overrides that should occur when mapping an integer sql type value to an underlying sql type name.

        The default implementation of this method does nothing. Subclasses should override in cases where:

        • database type metadata does not provide enough information to properly map
        • to support custom types (those not in Types)
        Overrides:
        registerSqlTypeToSqlTypeNameOverrides in class SQLDialect

      • encodePrimaryKey

        public void encodePrimaryKey​(String column,
                             StringBuffer sql)
        Description copied from class: SQLDialect
        Encodes the primary key definition in a CREATE TABLE statement.

        Subclasses should override this method if need be, the default implementation does the following: 

           
   encodeColumnName( column, sql );
   sql.append( " int PRIMARY KEY" );
        Overrides:
        encodePrimaryKey in class SQLDialect

      • postDropTable

        public void postDropTable​(String schemaName,
                          SimpleFeatureType featureType,
                          Connection cx)
        Description copied from class: SQLDialect
        Callback which executes after a table has been dropped.

        This base implementation does nothing, subclasses should override as need be.

        Overrides:
        postDropTable in class SQLDialect
        Parameters:
        schemaName - The database schema containing the table.
        featureType - The featureType/table being dropped.
        cx - The database connection.

      • encodeGeometryValue

        public void encodeGeometryValue​(Geometry value,
                                int dimension,
                                int srid,
                                StringBuffer sql)
        Description copied from class: BasicSQLDialect
        Encodes a geometry value in an sql statement.

        An implementations should serialize value into some exchange format which will then be transported to the underlying database. For example, consider an implementation which converts a geometry into its well known text representation: 

           
   sql.append( "GeomFromText('" );
   sql.append( new WKTWriter().write( value ) );
   sql.append( ")" );

        The srid parameter is the spatial reference system identifier of the geometry, or 0 if not known.

        Attention should be paid to emtpy geometries (g.isEmtpy() == true) as they cannot be encoded in WKB and several databases fail to handle them property. Common treatment is to equate them to NULL

        Specified by:
        encodeGeometryValue in class BasicSQLDialect

      • applyLimitOffset

        public void applyLimitOffset​(StringBuffer sql,
                             int limit,
                             int offset)
        Description copied from class: SQLDialect
        Alters the query provided so that limit and offset are natively dealt with. This might mean simply appending some extra directive to the query, or wrapping it into a bigger one.
        Overrides:
        applyLimitOffset in class SQLDialect

      • encodeValue

        public void encodeValue​(Object value,
                        Class type,
                        StringBuffer sql)
        Description copied from class: BasicSQLDialect
        Encodes a value in an sql statement.

        Subclasses may wish to override or extend this method to handle specific types. This default implementation does the following:

        1. The value is encoded via its Object.toString() representation.
        2. If type is a character type (extends CharSequence), it is wrapped in single quotes (').
        Overrides:
        encodeValue in class BasicSQLDialect

      • getDefaultVarcharSize

        public int getDefaultVarcharSize()
        Description copied from class: SQLDialect
        Determines the default length that a varchar field should be when creating datastore tables from feature types.

        Some dialects allow no length to be specified for varchar fields (PostGIS for example) however others require a maximum length to be set.

        Subclasses can override this method and either return -1 to specify that no length is required, or otherwise return an appropriate default length for varchars of that dialect.

        Overrides:
        getDefaultVarcharSize in class SQLDialect

      • decodeGeometryValue

        public Geometry decodeGeometryValue​(GeometryDescriptor gd,
                                    ResultSet rs,
                                    String column,
                                    GeometryFactory gf,
                                    Connection cnctn,
                                    Hints hints)
                             throws SQLException
        Description copied from class: SQLDialect
        Decodes a geometry value from the result of a query.

        This method is given direct access to a result set. The column parameter is the index into the result set which contains the geometric value.

        An implementation should deserialize the value provided by the result set into Geometry object. For example, consider an implementation which deserializes from well known text: 

           String wkt = rs.getString( column );
   if ( wkt == null ) {
     return null;
   }
   return new WKTReader(factory).read( wkt );
        Note that implementations must handle null values.

        The factory parameter should be used to instantiate any geometry objects.

        Specified by:
        decodeGeometryValue in class SQLDialect
        Throws:
        SQLException

      • getOptimizedBounds

        public List<ReferencedEnvelope> getOptimizedBounds​(String schema,
                                                   SimpleFeatureType featureType,
                                                   Connection cx)
                                            throws SQLException
        Description copied from class: SQLDialect
        Returns the bounds of all geometry columns in the layer using any approach that proves to be faster than the plain bounds aggregation (e.g., better than the "plain select extent(geom) from table" on PostGIS), or null if none exists or the fast method has not been enabled (e.g., if the fast method is just an estimate of the bounds you probably want the user to enable it manually)
        Overrides:
        getOptimizedBounds in class SQLDialect
        Parameters:
        schema - The database schema, if any, or null
        featureType - The feature type containing the geometry columns whose bounds need to computed. Mind, it may be retyped and thus contain less geometry columns than the table
        Returns:
        a list of referenced envelopes (some of which may be null or empty)
        Throws:
        SQLException

      • setFunctionEncodingEnabled

        public void setFunctionEncodingEnabled​(boolean functionEncodingEnabled)

      • getMapping

        public Class<?> getMapping​(String sqlTypeName)
        Description copied from class: SQLDialect
        Returns the java type mapped to the a specified sql type name defined by the dialect.

        If there is no such type mapped to sqlTypeName, null is returned.

        Overrides:
        getMapping in class SQLDialect
        Parameters:
        sqlTypeName - The name of the sql type.
        Returns:
        The mapped java class, or null. if no such mapping exists.

      • findGeometryClass

        public Class<?> findGeometryClass​(String geometryName)
        This method is used to retrieved the geometry class according the H2 metadata type formes eg : GEOMETRY, GEOMETRY(POLYGON), GEOMETRY(POLYGON, 4326), GEOMETRY(POLYGON Z, 4326)...
        Parameters:
        geometryName - the input geometry type name
        Returns:
        the corresponding JTS geometry class

      • initSpatialFunctions

        public static void initSpatialFunctions​(Connection cx)
                                 throws SQLException
        This method is used to init the H2GIS spatial functions
        Parameters:
        cx - connection to the database
        Throws:
        IOException
        SQLException