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 Details

  • Method Details

    • 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
    • getMapping

      public Class<?> getMapping(ResultSet columnMetaData, Connection cx) throws SQLException
      Description copied from class: SQLDialect
      Determines the class mapping for a particular column of a table.

      Implementing this method is optional. It is used to allow database to perform custom type mappings based on various column metadata. It is called before the mappings registered in SQLDialect.registerSqlTypeToClassMappings(Map) and are used to determine the mapping. Subclasses should implement as needed, this default implementation returns <code>null</code>. </p> <p> The <tt>columnMetaData</tt> argument is provided from {@link DatabaseMetaData#getColumns(String, String, String, String)}. </p>

      Overrides:
      getMapping in class SQLDialect
      Parameters:
      columnMetaData - The column metadata
      cx - The connection used to retrieve the metadata
      Returns:
      The class mapped to the to column, or null.
      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
    • lookupGeneratedValuesPostInsert

      public boolean lookupGeneratedValuesPostInsert()
      Description copied from class: SQLDialect
      Controls whether keys are looked up post or pre insert.

      When a row is inserted into a table, and a key is automatically generated it can be looked up before the insert occurs, or after the insert has been made. Returning false will cause the lookup to occur before the insert via SQLDialect.getNextAutoGeneratedValue(String, String, String, Connection). Returning true will cause the lookup to occur after the insert via SQLDialect.getLastAutoGeneratedValue(String, String, String, Connection).

      Subclasses returning false should implement:

      Subclasses returning true should implement:

      Overrides:
      lookupGeneratedValuesPostInsert in class SQLDialect
    • 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
    • postCreateTable

      public void postCreateTable(String schemaName, SimpleFeatureType featureType, Connection cx) throws SQLException
      Creates GEOMETRY_COLUMN registrations
      Overrides:
      postCreateTable in class SQLDialect
      Parameters:
      schemaName -
      featureType -
      cx -
      Throws:
      SQLException
    • 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
    • createFilterToSQL

      public FilterToSQL createFilterToSQL()
      Description copied from class: BasicSQLDialect
      Creates the filter encoder to be used by the datastore when encoding query predicates.

      Sublcasses can override this method to return a subclass of FilterToSQL if need be.

      Overrides:
      createFilterToSQL in class BasicSQLDialect
    • isLimitOffsetSupported

      public boolean isLimitOffsetSupported()
      Description copied from class: SQLDialect
      Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL.
      Overrides:
      isLimitOffsetSupported in class SQLDialect
    • 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
    • getDesiredTablesType

      public String[] getDesiredTablesType()
      Overrides:
      getDesiredTablesType in class SQLDialect
      Returns:
      Table types filtered from jdbc DatabaseMetaData
    • 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)
    • getH2GISVersion

      public Version getH2GISVersion(Connection conn) throws SQLException
      Returns the H2GIS version
      Parameters:
      conn -
      Returns:
      Throws:
      SQLException
    • getSRID

      public int getSRID(Connection connection, String schema, String table, String geometryColumnName) throws SQLException
      Get the srid of the table
      Parameters:
      connection -
      schema -
      table -
      geometryColumnName -
      Returns:
      Throws:
      SQLException
    • 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