Quelle SQLData.java Sprache: JAVA

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* accompanied this code).
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package java.sql;

/**
* 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 {@code SQLData} interface will be entered in the
* appropriate {@code Connection} object's type map along with the SQL
* name of the UDT for which it is a custom mapping.
* 
* Typically, a {@code SQLData} implementation
* will define a field for each attribute of an SQL structured type or a
* single field for an SQL {@code DISTINCT} type. When the UDT is
* retrieved from a data source with the {@code 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 {@code 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 {@code SQLData.readSQL} and
* {@code SQLData.writeSQL} methods. The {@code readSQL} method
* calls the appropriate {@code SQLInput} methods to read
* each attribute from an {@code SQLInput} object, and the
* {@code writeSQL} method calls {@code SQLOutput} methods
* to write each attribute back to the data source via an
* {@code SQLOutput} object.
* 
* An application programmer will not normally call {@code SQLData} methods
* directly, and the {@code SQLInput} and {@code SQLOutput} methods
* are called internally by {@code SQLData} methods, not by application code.
*
* @since 1.2
*/
public interface SQLData {

/**
 * 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
 * {@code SQLData}.
 *
 * @return the type name that was passed to the method {@code readSQL}
 * when this object was constructed and populated
 * @throws SQLException if there is a database access error
 * @throws SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @since 1.2
 */
 String getSQLTypeName() throws SQLException;

/**
 * Populates this object with data read from the database.
 * The implementation of the method must follow this protocol:
 * <UL>
 * <LI>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.
 * <LI>The method {@code readSQL} then
 * assigns the data to appropriate fields or
 * elements (of this or other objects).
 * Specifically, it must call the appropriate reader method
 * ({@code SQLInput.readString}, {@code 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.
 * </UL>
 * The JDBC driver initializes the input stream with a type map
 * before calling this method, which is used by the appropriate
 * {@code SQLInput} reader method on the stream.
 *
 * @param stream the {@code SQLInput} object from which to read the data for
 * the value that is being custom mapped
 * @param typeName the SQL type name of the value on the data stream
 * @throws SQLException if there is a database access error
 * @throws SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @see SQLInput
 * @since 1.2
 */
 void readSQL (SQLInput stream, String typeName) 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 {@code SQLOutput} writer
 * method(s) ({@code writeInt}, {@code 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.
 *
 * @param stream the {@code SQLOutput} object to which to write the data for
 * the value that was custom mapped
 * @throws SQLException if there is a database access error
 * @throws SQLFeatureNotSupportedException if the JDBC driver does not support
 * this method
 * @see SQLOutput
 * @since 1.2
 */
 void writeSQL (SQLOutput stream) throws SQLException;
}

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