org.postgresql.core

Interface ResultHandler

All Known Implementing Classes:

BatchResultHandler, PgResultSet.CursorResultHandler, PgStatement.StatementResultHandler, ResultHandlerBase, ResultHandlerDelegate

public interface ResultHandler

Callback interface for passing query results from the protocol-specific layer to the protocol-independent JDBC implementation code.

In general, a single query execution will consist of a number of calls to handleResultRows, handleCommandStatus, handleWarning, and handleError, followed by a single call to handleCompletion when query execution is complete. If the caller wants to throw SQLException, this can be done in handleCompletion.

Each executed query ends with a call to handleResultRows, handleCommandStatus, or handleError. If an error occurs, subsequent queries won't generate callbacks.

Method Summary

Modifier and Type	Method and Description
@Nullable SQLException	getException() Returns the first encountered exception.
@Nullable SQLWarning	getWarning() Returns the first encountered warning.
void	handleCommandStatus(String status, long updateCount, long insertOID) Called when a query that did not return a resultset completes.
void	handleCompletion() Called before a QueryExecutor method returns.
void	handleError(SQLException error) Called when an error occurs.
void	handleResultRows(Query fromQuery, Field[] fields, List<Tuple> tuples, @Nullable ResultCursor cursor) Called when result rows are received from a query.
void	handleWarning(SQLWarning warning) Called when a warning is emitted.
void	secureProgress() Callback for batch statements.

Method Detail

handleResultRows

void handleResultRows(Query fromQuery,
                      Field[] fields,
                      List<Tuple> tuples,
                      @Nullable ResultCursor cursor)

Called when result rows are received from a query.

Parameters:

fromQuery - the underlying query that generated these results; this may not be very specific (e.g. it may be a query that includes multiple statements).

fields - column metadata for the resultset; might be null if Query.QUERY_NO_METADATA was specified.

tuples - the actual data

cursor - a cursor to use to fetch additional data; null if no further results are present.

handleCommandStatus

void handleCommandStatus(String status,
                         long updateCount,
                         long insertOID)

Called when a query that did not return a resultset completes.

Parameters:

status - the command status string (e.g. "SELECT") returned by the backend

updateCount - the number of rows affected by an INSERT, UPDATE, DELETE, FETCH, or MOVE command; -1 if not available.

insertOID - for a single-row INSERT query, the OID of the newly inserted row; 0 if not available.

handleWarning

void handleWarning(SQLWarning warning)

Called when a warning is emitted.

Parameters:

warning - the warning that occurred.

handleError

void handleError(SQLException error)

Called when an error occurs. Subsequent queries are abandoned; in general the only calls between a handleError call and a subsequent handleCompletion call are handleError or handleWarning.

Parameters:

error - the error that occurred

handleCompletion

void handleCompletion()
               throws SQLException

Called before a QueryExecutor method returns. This method may throw a SQLException if desired; if it does, the QueryExecutor method will propagate that exception to the original caller.

Throws:

SQLException - if the handler wishes the original method to throw an exception.

secureProgress

void secureProgress()

Callback for batch statements. In case batch statement is executed in autocommit==true mode, the executor might commit "as it this it is best", so the result handler should track which statements are executed successfully and which are not.

getException

@Nullable SQLException getException()

Returns the first encountered exception. The rest are chained via SQLException.setNextException(SQLException)

Returns:

the first encountered exception

getWarning

@Nullable SQLWarning getWarning()

Returns the first encountered warning. The rest are chained via SQLException.setNextException(SQLException)

Returns:

the first encountered warning