419 lines
13 KiB
Java
419 lines
13 KiB
Java
package postgresql.jdbc2;
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// IMPORTANT NOTE: This file implements the JDBC 2 version of the driver.
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// If you make any modifications to this file, you must make sure that the
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// changes are also made (if relevent) to the related JDBC 1 class in the
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// postgresql.jdbc1 package.
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import java.io.*;
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import java.lang.*;
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import java.lang.reflect.*;
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import java.net.*;
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import java.util.*;
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import java.sql.*;
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import postgresql.Field;
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import postgresql.fastpath.*;
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import postgresql.largeobject.*;
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import postgresql.util.*;
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/**
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* $Id: Connection.java,v 1.2 1999/05/18 23:17:26 peter Exp $
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*
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* A Connection represents a session with a specific database. Within the
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* context of a Connection, SQL statements are executed and results are
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* returned.
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*
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* <P>A Connection's database is able to provide information describing
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* its tables, its supported SQL grammar, its stored procedures, the
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* capabilities of this connection, etc. This information is obtained
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* with the getMetaData method.
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*
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* <p><B>Note:</B> By default, the Connection automatically commits changes
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* after executing each statement. If auto-commit has been disabled, an
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* explicit commit must be done or database changes will not be saved.
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*
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* @see java.sql.Connection
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*/
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public class Connection extends postgresql.Connection implements java.sql.Connection
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{
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// This is a cache of the DatabaseMetaData instance for this connection
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protected DatabaseMetaData metadata;
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/**
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* SQL statements without parameters are normally executed using
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* Statement objects. If the same SQL statement is executed many
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* times, it is more efficient to use a PreparedStatement
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*
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* @return a new Statement object
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* @exception SQLException passed through from the constructor
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*/
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public java.sql.Statement createStatement() throws SQLException
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{
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return new Statement(this);
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}
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/**
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* A SQL statement with or without IN parameters can be pre-compiled
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* and stored in a PreparedStatement object. This object can then
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* be used to efficiently execute this statement multiple times.
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*
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* <B>Note:</B> This method is optimized for handling parametric
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* SQL statements that benefit from precompilation if the drivers
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* supports precompilation. PostgreSQL does not support precompilation.
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* In this case, the statement is not sent to the database until the
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* PreparedStatement is executed. This has no direct effect on users;
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* however it does affect which method throws certain SQLExceptions
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*
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* @param sql a SQL statement that may contain one or more '?' IN
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* parameter placeholders
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* @return a new PreparedStatement object containing the pre-compiled
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* statement.
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* @exception SQLException if a database access error occurs.
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*/
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public java.sql.PreparedStatement prepareStatement(String sql) throws SQLException
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{
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return new PreparedStatement(this, sql);
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}
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/**
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* A SQL stored procedure call statement is handled by creating a
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* CallableStatement for it. The CallableStatement provides methods
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* for setting up its IN and OUT parameters and methods for executing
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* it.
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*
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* <B>Note:</B> This method is optimised for handling stored procedure
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* call statements. Some drivers may send the call statement to the
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* database when the prepareCall is done; others may wait until the
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* CallableStatement is executed. This has no direct effect on users;
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* however, it does affect which method throws certain SQLExceptions
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*
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* @param sql a SQL statement that may contain one or more '?' parameter
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* placeholders. Typically this statement is a JDBC function call
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* escape string.
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* @return a new CallableStatement object containing the pre-compiled
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* SQL statement
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* @exception SQLException if a database access error occurs
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*/
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public java.sql.CallableStatement prepareCall(String sql) throws SQLException
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{
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throw new PSQLException("postgresql.con.call");
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// return new CallableStatement(this, sql);
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}
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/**
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* A driver may convert the JDBC sql grammar into its system's
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* native SQL grammar prior to sending it; nativeSQL returns the
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* native form of the statement that the driver would have sent.
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*
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* @param sql a SQL statement that may contain one or more '?'
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* parameter placeholders
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* @return the native form of this statement
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* @exception SQLException if a database access error occurs
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*/
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public String nativeSQL(String sql) throws SQLException
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{
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return sql;
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}
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/**
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* If a connection is in auto-commit mode, than all its SQL
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* statements will be executed and committed as individual
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* transactions. Otherwise, its SQL statements are grouped
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* into transactions that are terminated by either commit()
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* or rollback(). By default, new connections are in auto-
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* commit mode. The commit occurs when the statement completes
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* or the next execute occurs, whichever comes first. In the
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* case of statements returning a ResultSet, the statement
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* completes when the last row of the ResultSet has been retrieved
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* or the ResultSet has been closed. In advanced cases, a single
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* statement may return multiple results as well as output parameter
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* values. Here the commit occurs when all results and output param
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* values have been retrieved.
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*
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* @param autoCommit - true enables auto-commit; false disables it
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* @exception SQLException if a database access error occurs
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*/
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public void setAutoCommit(boolean autoCommit) throws SQLException
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{
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if (this.autoCommit == autoCommit)
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return;
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if (autoCommit)
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ExecSQL("end");
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else
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ExecSQL("begin");
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this.autoCommit = autoCommit;
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}
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/**
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* gets the current auto-commit state
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*
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* @return Current state of the auto-commit mode
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* @exception SQLException (why?)
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* @see setAutoCommit
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*/
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public boolean getAutoCommit() throws SQLException
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{
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return this.autoCommit;
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}
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/**
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* The method commit() makes all changes made since the previous
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* commit/rollback permanent and releases any database locks currently
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* held by the Connection. This method should only be used when
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* auto-commit has been disabled. (If autoCommit == true, then we
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* just return anyhow)
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*
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* @exception SQLException if a database access error occurs
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* @see setAutoCommit
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*/
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public void commit() throws SQLException
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{
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if (autoCommit)
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return;
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ExecSQL("commit");
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autoCommit = true;
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ExecSQL("begin");
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autoCommit = false;
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}
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/**
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* The method rollback() drops all changes made since the previous
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* commit/rollback and releases any database locks currently held by
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* the Connection.
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*
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* @exception SQLException if a database access error occurs
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* @see commit
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*/
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public void rollback() throws SQLException
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{
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if (autoCommit)
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return;
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ExecSQL("rollback");
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autoCommit = true;
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ExecSQL("begin");
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autoCommit = false;
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}
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/**
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* In some cases, it is desirable to immediately release a Connection's
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* database and JDBC resources instead of waiting for them to be
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* automatically released (cant think why off the top of my head)
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*
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* <B>Note:</B> A Connection is automatically closed when it is
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* garbage collected. Certain fatal errors also result in a closed
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* connection.
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*
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* @exception SQLException if a database access error occurs
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*/
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public void close() throws SQLException
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{
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if (pg_stream != null)
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{
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try
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{
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pg_stream.close();
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} catch (IOException e) {}
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pg_stream = null;
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}
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}
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/**
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* Tests to see if a Connection is closed
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*
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* @return the status of the connection
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* @exception SQLException (why?)
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*/
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public boolean isClosed() throws SQLException
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{
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return (pg_stream == null);
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}
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/**
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* A connection's database is able to provide information describing
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* its tables, its supported SQL grammar, its stored procedures, the
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* capabilities of this connection, etc. This information is made
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* available through a DatabaseMetaData object.
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*
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* @return a DatabaseMetaData object for this connection
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* @exception SQLException if a database access error occurs
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*/
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public java.sql.DatabaseMetaData getMetaData() throws SQLException
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{
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if(metadata==null)
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metadata = new DatabaseMetaData(this);
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return metadata;
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}
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/**
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* You can put a connection in read-only mode as a hunt to enable
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* database optimizations
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*
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* <B>Note:</B> setReadOnly cannot be called while in the middle
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* of a transaction
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*
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* @param readOnly - true enables read-only mode; false disables it
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* @exception SQLException if a database access error occurs
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*/
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public void setReadOnly (boolean readOnly) throws SQLException
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{
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this.readOnly = readOnly;
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}
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/**
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* Tests to see if the connection is in Read Only Mode. Note that
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* we cannot really put the database in read only mode, but we pretend
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* we can by returning the value of the readOnly flag
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*
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* @return true if the connection is read only
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* @exception SQLException if a database access error occurs
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*/
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public boolean isReadOnly() throws SQLException
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{
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return readOnly;
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}
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/**
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* A sub-space of this Connection's database may be selected by
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* setting a catalog name. If the driver does not support catalogs,
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* it will silently ignore this request
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*
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* @exception SQLException if a database access error occurs
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*/
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public void setCatalog(String catalog) throws SQLException
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{
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// No-op
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}
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/**
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* Return the connections current catalog name, or null if no
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* catalog name is set, or we dont support catalogs.
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*
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* @return the current catalog name or null
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* @exception SQLException if a database access error occurs
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*/
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public String getCatalog() throws SQLException
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{
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return null;
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}
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/**
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* You can call this method to try to change the transaction
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* isolation level using one of the TRANSACTION_* values.
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*
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* <B>Note:</B> setTransactionIsolation cannot be called while
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* in the middle of a transaction
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*
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* @param level one of the TRANSACTION_* isolation values with
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* the exception of TRANSACTION_NONE; some databases may
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* not support other values
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* @exception SQLException if a database access error occurs
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* @see java.sql.DatabaseMetaData#supportsTransactionIsolationLevel
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*/
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public void setTransactionIsolation(int level) throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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/**
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* Get this Connection's current transaction isolation mode.
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*
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* @return the current TRANSACTION_* mode value
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* @exception SQLException if a database access error occurs
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*/
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public int getTransactionIsolation() throws SQLException
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{
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return java.sql.Connection.TRANSACTION_SERIALIZABLE;
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}
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/**
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* The first warning reported by calls on this Connection is
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* returned.
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*
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* <B>Note:</B> Sebsequent warnings will be changed to this
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* SQLWarning
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*
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* @return the first SQLWarning or null
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* @exception SQLException if a database access error occurs
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*/
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public SQLWarning getWarnings() throws SQLException
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{
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return firstWarning;
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}
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/**
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* After this call, getWarnings returns null until a new warning
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* is reported for this connection.
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*
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* @exception SQLException if a database access error occurs
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*/
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public void clearWarnings() throws SQLException
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{
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firstWarning = null;
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}
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/**
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* This overides the method in postgresql.Connection and returns a
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* ResultSet.
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*/
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protected java.sql.ResultSet getResultSet(postgresql.Connection conn, Field[] fields, Vector tuples, String status, int updateCount) throws SQLException
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{
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return new postgresql.jdbc2.ResultSet((postgresql.jdbc2.Connection)conn,fields,tuples,status,updateCount);
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}
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// *****************
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// JDBC 2 extensions
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// *****************
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public java.sql.Statement createStatement(int resultSetType,int resultSetConcurrency) throws SQLException
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{
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// normal create followed by 2 sets?
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throw postgresql.Driver.notImplemented();
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}
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public java.sql.PreparedStatement prepareStatement(String sql,int resultSetType,int resultSetConcurrency) throws SQLException
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{
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// normal prepare followed by 2 sets?
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throw postgresql.Driver.notImplemented();
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}
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public java.sql.CallableStatement prepareCall(String sql,int resultSetType,int resultSetConcurrency) throws SQLException
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{
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// normal prepare followed by 2 sets?
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throw postgresql.Driver.notImplemented();
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}
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public int getResultSetConcurrency() throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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public int getResultSetType() throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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public java.util.Map getTypeMap() throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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public void setResultSetConcurrency(int value) throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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public void setResultSetType(int type) throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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public void setTypeMap(java.util.Map map) throws SQLException
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{
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throw postgresql.Driver.notImplemented();
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}
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}
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// ***********************************************************************
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