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0e583068579748ad528685fa6040636b374177c6
postgres/src/interfaces/jdbc/postgresql/Connection.java

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package postgresql;
import java.io.*;
import java.lang.*;
import java.net.*;
import java.util.*;
import java.sql.*;
import postgresql.*;
/**
* @version 1.0 15-APR-1997
* @author <A HREF="mailto:adrian@hottub.org">Adrian Hall</A>
*
* A Connection represents a session with a specific database. Within the
* context of a Connection, SQL statements are executed and results are
* returned.
*
* A Connection's database is able to provide information describing
* its tables, its supported SQL grammar, its stored procedures, the
* capabilities of this connection, etc. This information is obtained
* with the getMetaData method.
*
* <B>Note:</B> By default, the Connection automatically commits changes
* after executing each statement. If auto-commit has been disabled, an
* explicit commit must be done or database changes will not be saved.
*
* @see java.sql.Connection
*/
public class Connection implements java.sql.Connection
{
protected PG_Stream pg_stream;
private String PG_HOST;
private int PG_PORT;
private String PG_USER;
private String PG_PASSWORD;
private String PG_DATABASE;
private boolean PG_STATUS;
private boolean PG_AUTH; // true, then password auth used
public boolean CONNECTION_OK = true;
public boolean CONNECTION_BAD = false;
private int STARTUP_CODE = STARTUP_USER;
private static final int STARTUP_USER = 7; // User auth
private static final int STARTUP_PASS = 14; // Password auth
private static final int STARTUP_LEN = 288; // Length of a startup packet
private boolean autoCommit = true;
private boolean readOnly = false;
protected Driver this_driver;
private String this_url;
private String cursor = null; // The positioned update cursor name
// This is false for US, true for European date formats
protected boolean europeanDates = false;
// Now handle notices as warnings, so things like "show" now work
protected SQLWarning firstWarning = null;
/**
* Connect to a PostgreSQL database back end.
*
* @param host the hostname of the database back end
* @param port the port number of the postmaster process
* @param info a Properties[] thing of the user and password
* @param database the database to connect to
* @param u the URL of the connection
* @param d the Driver instantation of the connection
* @return a valid connection profile
* @exception SQLException if a database access error occurs
*/
public Connection(String host, int port, Properties info, String database, String url, Driver d) throws SQLException
{
int len = STARTUP_LEN; // Length of a startup packet
this_driver = d;
this_url = new String(url);
PG_DATABASE = new String(database);
PG_PASSWORD = new String(info.getProperty("password"));
PG_USER = new String(info.getProperty("user"));
PG_PORT = port;
PG_HOST = new String(host);
PG_STATUS = CONNECTION_BAD;
if(info.getProperty("auth") != null) {
PG_AUTH=true;
STARTUP_CODE=STARTUP_PASS;
} else {
STARTUP_CODE=STARTUP_USER;
}
try
{
pg_stream = new PG_Stream(host, port);
} catch (IOException e) {
throw new SQLException ("Connection failed: " + e.toString());
}
// Now we need to construct and send a startup packet
try
{
pg_stream.SendInteger(len, 4); len -= 4;
pg_stream.SendInteger(STARTUP_CODE, 4); len -= 4;
pg_stream.Send(database.getBytes(), 64); len -= 64;
pg_stream.Send(PG_USER.getBytes(), len);
// Send the password packet if required
if(PG_AUTH) {
len=STARTUP_LEN;
pg_stream.SendInteger(len, 4); len -= 4;
pg_stream.SendInteger(STARTUP_PASS, 4); len -= 4;
pg_stream.Send(PG_USER.getBytes(), PG_USER.length());
len-=PG_USER.length();
pg_stream.SendInteger(0,1); len -= 1;
pg_stream.Send(PG_PASSWORD.getBytes(), len);
}
} catch (IOException e) {
throw new SQLException("Connection failed: " + e.toString());
}
// Find out the date style by issuing the SQL: show datestyle
// This actually issues a warning, and our own warning handling
// code handles this itself.
//
// Also, this query replaced the NULL query issued to test the
// connection.
//
clearWarnings();
ExecSQL("show datestyle");
// Mark the connection as ok, and cleanup
clearWarnings();
PG_STATUS = CONNECTION_OK;
}
/**
* SQL statements without parameters are normally executed using
* Statement objects. If the same SQL statement is executed many
* times, it is more efficient to use a PreparedStatement
*
* @return a new Statement object
* @exception SQLException passed through from the constructor
*/
public java.sql.Statement createStatement() throws SQLException
{
return new Statement(this);
}
/**
* A SQL statement with or without IN parameters can be pre-compiled
* and stored in a PreparedStatement object. This object can then
* be used to efficiently execute this statement multiple times.
*
* <B>Note:</B> This method is optimized for handling parametric
* SQL statements that benefit from precompilation if the drivers
* supports precompilation. PostgreSQL does not support precompilation.
* In this case, the statement is not sent to the database until the
* PreparedStatement is executed. This has no direct effect on users;
* however it does affect which method throws certain SQLExceptions
*
* @param sql a SQL statement that may contain one or more '?' IN
* parameter placeholders
* @return a new PreparedStatement object containing the pre-compiled
* statement.
* @exception SQLException if a database access error occurs.
*/
public java.sql.PreparedStatement prepareStatement(String sql) throws SQLException
{
return new PreparedStatement(this, sql);
}
/**
* A SQL stored procedure call statement is handled by creating a
* CallableStatement for it. The CallableStatement provides methods
* for setting up its IN and OUT parameters and methods for executing
* it.
*
* <B>Note:</B> This method is optimised for handling stored procedure
* call statements. Some drivers may send the call statement to the
* database when the prepareCall is done; others may wait until the
* CallableStatement is executed. This has no direct effect on users;
* however, it does affect which method throws certain SQLExceptions
*
* @param sql a SQL statement that may contain one or more '?' parameter
* placeholders. Typically this statement is a JDBC function call
* escape string.
* @return a new CallableStatement object containing the pre-compiled
* SQL statement
* @exception SQLException if a database access error occurs
*/
public java.sql.CallableStatement prepareCall(String sql) throws SQLException
{
throw new SQLException("Callable Statements are not supported at this time");
// return new CallableStatement(this, sql);
}
/**
* A driver may convert the JDBC sql grammar into its system's
* native SQL grammar prior to sending it; nativeSQL returns the
* native form of the statement that the driver would have sent.
*
* @param sql a SQL statement that may contain one or more '?'
* parameter placeholders
* @return the native form of this statement
* @exception SQLException if a database access error occurs
*/
public String nativeSQL(String sql) throws SQLException
{
return sql;
}
/**
* If a connection is in auto-commit mode, than all its SQL
* statements will be executed and committed as individual
* transactions. Otherwise, its SQL statements are grouped
* into transactions that are terminated by either commit()
* or rollback(). By default, new connections are in auto-
* commit mode. The commit occurs when the statement completes
* or the next execute occurs, whichever comes first. In the
* case of statements returning a ResultSet, the statement
* completes when the last row of the ResultSet has been retrieved
* or the ResultSet has been closed. In advanced cases, a single
* statement may return multiple results as well as output parameter
* values. Here the commit occurs when all results and output param
* values have been retrieved.
*
* @param autoCommit - true enables auto-commit; false disables it
* @exception SQLException if a database access error occurs
*/
public void setAutoCommit(boolean autoCommit) throws SQLException
{
if (this.autoCommit == autoCommit)
return;
if (autoCommit)
ExecSQL("end");
else
ExecSQL("begin");
this.autoCommit = autoCommit;
}
/**
* gets the current auto-commit state
*
* @return Current state of the auto-commit mode
* @exception SQLException (why?)
* @see setAutoCommit
*/
public boolean getAutoCommit() throws SQLException
{
return this.autoCommit;
}
/**
* The method commit() makes all changes made since the previous
* commit/rollback permanent and releases any database locks currently
* held by the Connection. This method should only be used when
* auto-commit has been disabled. (If autoCommit == true, then we
* just return anyhow)
*
* @exception SQLException if a database access error occurs
* @see setAutoCommit
*/
public void commit() throws SQLException
{
if (autoCommit)
return;
ExecSQL("commit");
autoCommit = true;
ExecSQL("begin");
autoCommit = false;
}
/**
* The method rollback() drops all changes made since the previous
* commit/rollback and releases any database locks currently held by
* the Connection.
*
* @exception SQLException if a database access error occurs
* @see commit
*/
public void rollback() throws SQLException
{
if (autoCommit)
return;
ExecSQL("rollback");
autoCommit = true;
ExecSQL("begin");
autoCommit = false;
}
/**
* In some cases, it is desirable to immediately release a Connection's
* database and JDBC resources instead of waiting for them to be
* automatically released (cant think why off the top of my head)
*
* <B>Note:</B> A Connection is automatically closed when it is
* garbage collected. Certain fatal errors also result in a closed
* connection.
*
* @exception SQLException if a database access error occurs
*/
public void close() throws SQLException
{
if (pg_stream != null)
{
try
{
pg_stream.close();
} catch (IOException e) {}
pg_stream = null;
}
}
/**
* Tests to see if a Connection is closed
*
* @return the status of the connection
* @exception SQLException (why?)
*/
public boolean isClosed() throws SQLException
{
return (pg_stream == null);
}
/**
* A connection's database is able to provide information describing
* its tables, its supported SQL grammar, its stored procedures, the
* capabilities of this connection, etc. This information is made
* available through a DatabaseMetaData object.
*
* @return a DatabaseMetaData object for this connection
* @exception SQLException if a database access error occurs
*/
public java.sql.DatabaseMetaData getMetaData() throws SQLException
{
return new DatabaseMetaData(this);
}
/**
* You can put a connection in read-only mode as a hunt to enable
* database optimizations
*
* <B>Note:</B> setReadOnly cannot be called while in the middle
* of a transaction
*
* @param readOnly - true enables read-only mode; false disables it
* @exception SQLException if a database access error occurs
*/
public void setReadOnly (boolean readOnly) throws SQLException
{
this.readOnly = readOnly;
}
/**
* Tests to see if the connection is in Read Only Mode. Note that
* we cannot really put the database in read only mode, but we pretend
* we can by returning the value of the readOnly flag
*
* @return true if the connection is read only
* @exception SQLException if a database access error occurs
*/
public boolean isReadOnly() throws SQLException
{
return readOnly;
}
/**
* A sub-space of this Connection's database may be selected by
* setting a catalog name. If the driver does not support catalogs,
* it will silently ignore this request
*
* @exception SQLException if a database access error occurs
*/
public void setCatalog(String catalog) throws SQLException
{
// No-op
}
/**
* Return the connections current catalog name, or null if no
* catalog name is set, or we dont support catalogs.
*
* @return the current catalog name or null
* @exception SQLException if a database access error occurs
*/
public String getCatalog() throws SQLException
{
return null;
}
/**
* You can call this method to try to change the transaction
* isolation level using one of the TRANSACTION_* values.
*
* <B>Note:</B> setTransactionIsolation cannot be called while
* in the middle of a transaction
*
* @param level one of the TRANSACTION_* isolation values with
* the exception of TRANSACTION_NONE; some databases may
* not support other values
* @exception SQLException if a database access error occurs
* @see java.sql.DatabaseMetaData#supportsTransactionIsolationLevel
*/
public void setTransactionIsolation(int level) throws SQLException
{
throw new SQLException("Transaction Isolation Levels are not implemented");
}
/**
* Get this Connection's current transaction isolation mode.
*
* @return the current TRANSACTION_* mode value
* @exception SQLException if a database access error occurs
*/
public int getTransactionIsolation() throws SQLException
{
return java.sql.Connection.TRANSACTION_SERIALIZABLE;
}
/**
* The first warning reported by calls on this Connection is
* returned.
*
* <B>Note:</B> Sebsequent warnings will be changed to this
* SQLWarning
*
* @return the first SQLWarning or null
* @exception SQLException if a database access error occurs
*/
public SQLWarning getWarnings() throws SQLException
{
return firstWarning;
}
/**
* After this call, getWarnings returns null until a new warning
* is reported for this connection.
*
* @exception SQLException if a database access error occurs
*/
public void clearWarnings() throws SQLException
{
firstWarning = null;
}
// **********************************************************
// END OF PUBLIC INTERFACE
// **********************************************************
/**
* This adds a warning to the warning chain
*/
public void addWarning(String msg)
{
// Add the warning to the chain
if(firstWarning!=null)
firstWarning.setNextWarning(new SQLWarning(msg));
else
firstWarning = new SQLWarning(msg);
// Now check for some specific messages
// This is generated by the SQL "show datestyle"
if(msg.startsWith("NOTICE:DateStyle")) {
if(msg.indexOf("with US")==-1)
europeanDates=true;
else
europeanDates=false;
System.err.println("europeanDates="+europeanDates);
}
}
/**
* Send a query to the backend. Returns one of the ResultSet
* objects.
*
* <B>Note:</B> there does not seem to be any method currently
* in existance to return the update count.
*
* @param sql the SQL statement to be executed
* @return a ResultSet holding the results
* @exception SQLException if a database error occurs
*/
public synchronized ResultSet ExecSQL(String sql) throws SQLException
{
Field[] fields = null;
Vector tuples = new Vector();
byte[] buf = new byte[sql.length()];
int fqp = 0;
boolean hfr = false;
String recv_status = null, msg;
SQLException final_error = null;
if (sql.length() > 8192)
throw new SQLException("SQL Statement too long: " + sql);
try
{
pg_stream.SendChar('Q');
buf = sql.getBytes();
pg_stream.Send(buf);
pg_stream.SendChar(0);
} catch (IOException e) {
throw new SQLException("I/O Error: " + e.toString());
}
while (!hfr || fqp > 0)
{
int c = pg_stream.ReceiveChar();
switch (c)
{
case 'A': // Asynchronous Notify
int pid = pg_stream.ReceiveInteger(4);
msg = pg_stream.ReceiveString(8192);
break;
case 'B': // Binary Data Transfer
if (fields == null)
throw new SQLException("Tuple received before MetaData");
tuples.addElement(pg_stream.ReceiveTuple(fields.length, true));
break;
case 'C': // Command Status
recv_status = pg_stream.ReceiveString(8192);
if (fields != null)
hfr = true;
else
{
try
{
pg_stream.SendChar('Q');
pg_stream.SendChar(' ');
pg_stream.SendChar(0);
} catch (IOException e) {
throw new SQLException("I/O Error: " + e.toString());
}
fqp++;
}
break;
case 'D': // Text Data Transfer
if (fields == null)
throw new SQLException("Tuple received before MetaData");
tuples.addElement(pg_stream.ReceiveTuple(fields.length, false));
break;
case 'E': // Error Message
msg = pg_stream.ReceiveString(4096);
final_error = new SQLException(msg);
hfr = true;
break;
case 'I': // Empty Query
int t = pg_stream.ReceiveChar();
if (t != 0)
throw new SQLException("Garbled Data");
if (fqp > 0)
fqp--;
if (fqp == 0)
hfr = true;
break;
case 'N': // Error Notification
msg = pg_stream.ReceiveString(4096);
PrintStream log = DriverManager.getLogStream();
if(log!=null) log.println(msg);
addWarning(msg);
break;
case 'P': // Portal Name
String pname = pg_stream.ReceiveString(8192);
break;
case 'T': // MetaData Field Description
if (fields != null)
throw new SQLException("Cannot handle multiple result groups");
fields = ReceiveFields();
break;
default:
throw new SQLException("Unknown Response Type: " + (char)c);
}
}
if (final_error != null)
throw final_error;
return new ResultSet(this, fields, tuples, recv_status, 1);
}
/**
* Receive the field descriptions from the back end
*
* @return an array of the Field object describing the fields
* @exception SQLException if a database error occurs
*/
private Field[] ReceiveFields() throws SQLException
{
int nf = pg_stream.ReceiveInteger(2), i;
Field[] fields = new Field[nf];
for (i = 0 ; i < nf ; ++i)
{
String typname = pg_stream.ReceiveString(8192);
int typid = pg_stream.ReceiveInteger(4);
int typlen = pg_stream.ReceiveInteger(2);
fields[i] = new Field(this, typname, typid, typlen);
}
return fields;
}
/**
* In SQL, a result table can be retrieved through a cursor that
* is named. The current row of a result can be updated or deleted
* using a positioned update/delete statement that references the
* cursor name.
*
* We support one cursor per connection.
*
* setCursorName sets the cursor name.
*
* @param cursor the cursor name
* @exception SQLException if a database access error occurs
*/
public void setCursorName(String cursor) throws SQLException
{
this.cursor = cursor;
}
/**
* getCursorName gets the cursor name.
*
* @return the current cursor name
* @exception SQLException if a database access error occurs
*/
public String getCursorName() throws SQLException
{
return cursor;
}
/**
* We are required to bring back certain information by
* the DatabaseMetaData class. These functions do that.
*
* Method getURL() brings back the URL (good job we saved it)
*
* @return the url
* @exception SQLException just in case...
*/
public String getURL() throws SQLException
{
return this_url;
}
/**
* Method getUserName() brings back the User Name (again, we
* saved it)
*
* @return the user name
* @exception SQLException just in case...
*/
public String getUserName() throws SQLException
{
return PG_USER;
}
/**
* This method is not part of the Connection interface. Its is an extension
* that allows access to the PostgreSQL Large Object API
*
* @return PGlobj class that implements the API
*/
public PGlobj getLargeObjectAPI() throws SQLException
{
return new PGlobj(this);
}
}
// ***********************************************************************
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