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Java™ Platform Standard Ed. 6 |
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public interface SQLData
The 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 SQLData
interface will be entered in the
appropriate Connection
object's type map along with the SQL
name of the UDT for which it is a custom mapping.
Typically, a SQLData
implementation
will define a field for each attribute of an SQL structured type or a
single field for an SQL DISTINCT
type. When the UDT is
retrieved from a data source with the ResultSet.getObject
method, 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.setObject
method,
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 SQLData.readSQL
and
SQLData.writeSQL
methods. The readSQL
method
calls the appropriate SQLInput
methods to read
each attribute from an SQLInput
object, and the
writeSQL
method calls SQLOutput
methods
to write each attribute back to the data source via an
SQLOutput
object.
An application programmer will not normally call SQLData
methods
directly, and the SQLInput
and SQLOutput
methods
are called internally by SQLData
methods, not by application code.
Method Summary | |
---|---|
String |
getSQLTypeName()
Returns the fully-qualified name of the SQL user-defined type that this object represents. |
void |
readSQL(SQLInput stream,
String typeName)
Populates this object with data read from the database. |
void |
writeSQL(SQLOutput stream)
Writes this object to the given SQL data stream, converting it back to its SQL value in the data source. |
Method Detail |
---|
String getSQLTypeName() throws SQLException
SQLData
.
readSQL
when this object was constructed and populated
SQLException
- if there is a database access error
SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodvoid readSQL(SQLInput stream, String typeName) throws SQLException
readSQL
then
assigns the data to appropriate fields or
elements (of this or other objects).
Specifically, it must call the appropriate reader method
(SQLInput.readString
, 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.
SQLInput
reader method on the stream.
stream
- the SQLInput
object from which to read the data for
the value that is being custom mappedtypeName
- 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 methodSQLInput
void writeSQL(SQLOutput stream) throws SQLException
SQLOutput
writer
method(s) (writeInt
, 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.
stream
- the SQLOutput
object to which to write the data for
the value that was custom mapped
SQLException
- if there is a database access error
SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodSQLOutput
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Java™ Platform Standard Ed. 6 |
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