public interface SQLDataThe interface used for the custom mapping of an SQL user-defined type (UDT) to a class in the Java programming language. The class object for a class implementing the
SQLDatainterface will be entered in the appropriate
Connectionobject's type map along with the SQL name of the UDT for which it is a custom mapping.
SQLDataimplementation will define a field for each attribute of an SQL structured type or a single field for an SQL
DISTINCTtype. When the UDT is retrieved from a data source with the
ResultSet.getObjectmethod, it will be mapped as an instance of this class. A programmer can operate on this class instance just as on any other object in the Java programming language and then store any changes made to it by calling the
PreparedStatement.setObjectmethod, which will map it back to the SQL type.
It is expected that the implementation of the class for a custom mapping will be done by a tool. In a typical implementation, the programmer would simply supply the name of the SQL UDT, the name of the class to which it is being mapped, and the names of the fields to which each of the attributes of the UDT is to be mapped. The tool will use this information to implement the
readSQLmethod calls the appropriate
SQLInputmethods to read each attribute from an
SQLInputobject, and the
SQLOutputmethods to write each attribute back to the data source via an
An application programmer will not normally call
SQLDatamethods directly, and the
SQLOutputmethods are called internally by
SQLDatamethods, not by application code.
Modifier and Type Method Description
getSQLTypeName()Returns the fully-qualified name of the SQL user-defined type that this object represents.
readSQL(SQLInput stream, String typeName)Populates this object with data read from the database.
writeSQL(SQLOutput stream)Writes this object to the given SQL data stream, converting it back to its SQL value in the data source.
String getSQLTypeName() throws SQLExceptionReturns the fully-qualified name of the SQL user-defined type that this object represents. This method is called by the JDBC driver to get the name of the UDT instance that is being mapped to this instance of
void readSQL(SQLInput stream, String typeName) throws SQLExceptionPopulates this object with data read from the database. The implementation of the method must follow this protocol:
- It must read each of the attributes or elements of the SQL type from the given input stream. This is done by calling a method of the input stream to read each item, in the order that they appear in the SQL definition of the type.
- The method
readSQLthen assigns the data to appropriate fields or elements (of this or other objects). Specifically, it must call the appropriate reader method (
SQLInput.readBigDecimal, and so on) method(s) to do the following: for a distinct type, read its single data element; for a structured type, read a value for each attribute of the SQL type.
SQLInputreader method on the stream.
SQLInputobject from which to read the data for the value that is being custom mapped
typeName- the SQL type name of the value on the data stream
SQLException- if there is a database access error
SQLFeatureNotSupportedException- if the JDBC driver does not support this method
- See Also:
void writeSQL(SQLOutput stream) throws SQLExceptionWrites this object to the given SQL data stream, converting it back to its SQL value in the data source. The implementation of the method must follow this protocol:
It must write each of the attributes of the SQL type to the given output stream. This is done by calling a method of the output stream to write each item, in the order that they appear in the SQL definition of the type. Specifically, it must call the appropriate
SQLOutputwriter method(s) (
writeString, and so on) to do the following: for a Distinct Type, write its single data element; for a Structured Type, write a value for each attribute of the SQL type.