java.sql: public interface: SQLData

java.sql
public interface: SQLData [javadoc | source] 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.

since: 1.2 -

Method from java.sql.SQLData Summary:
getSQLTypeName, readSQL, writeSQL

Method from java.sql.SQLData Detail:
public String getSQLTypeName() throws SQLException Returns 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 `SQLData`.
public void readSQL(SQLInput stream, String typeName) throws SQLException Populates 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 `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. The JDBC driver initializes the input stream with a type map before calling this method, which is used by the appropriate `SQLInput` reader method on the stream.
public void writeSQL(SQLOutput stream) throws SQLException Writes 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 `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.

Method from java.sql.SQLData Detail:

 public 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
SQLData.

 public  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 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.

The JDBC driver initializes the input stream with a type map
before calling this method, which is used by the appropriate
SQLInput reader method on the stream.

 public  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 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.