数据库编程

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Java

Connection.java：源码内容

/*
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.mysql.jdbc;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.math.BigDecimal;
import java.net.URL;
import java.sql.Clob;
import java.sql.Date;
import java.sql.ParameterMetaData;
import java.sql.Ref;
import java.sql.SQLException;
import java.sql.Savepoint;
import java.sql.Time;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.TimeZone;
/**
* 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.
*
*
* @author Mark Matthews
* @version $Id: Connection.java,v 1.31.2.55 2004/02/13 22:33:50 mmatthew Exp $
*
* @see java.sql.Connection
*/
public class Connection implements java.sql.Connection {
// The command used to "ping" the database.
// Newer versions of MySQL server have a ping() command,
// but this works for everything
private static final String PING_COMMAND = "SELECT 1";
/**
* Map mysql transaction isolation level name to
* java.sql.Connection.TRANSACTION_XXX
*/
private static Map mapTransIsolationName2Value = null;
/**
* The mapping between MySQL charset names and Java charset names.
* Initialized by loadCharacterSetMapping()
*/
private static Map charsetMap;
/** Table of multi-byte charsets. Initialized by loadCharacterSetMapping() */
private static Map multibyteCharsetsMap;
/** Default socket factory classname */
private static final String DEFAULT_SOCKET_FACTORY = StandardSocketFactory.class
.getName();
static {
loadCharacterSetMapping();
mapTransIsolationName2Value = new HashMap(8);
mapTransIsolationName2Value.put("READ-UNCOMMITED",
new Integer(TRANSACTION_READ_UNCOMMITTED));
mapTransIsolationName2Value.put("READ-UNCOMMITTED",
new Integer(TRANSACTION_READ_UNCOMMITTED));
mapTransIsolationName2Value.put("READ-COMMITTED",
new Integer(TRANSACTION_READ_COMMITTED));
mapTransIsolationName2Value.put("REPEATABLE-READ",
new Integer(TRANSACTION_REPEATABLE_READ));
mapTransIsolationName2Value.put("SERIALIZABLE",
new Integer(TRANSACTION_SERIALIZABLE));
}
/**
* Marker for character set converter not being available (not written,
* multibyte, etc) Used to prevent multiple instantiation requests.
*/
private final static Object CHARSET_CONVERTER_NOT_AVAILABLE_MARKER = new Object();
/** Internal DBMD to use for various database-version specific features */
private DatabaseMetaData dbmd = null;
/** The list of host(s) to try and connect to */
private List hostList = null;
/** A map of SQL to parsed prepared statement parameters. */
private Map cachedPreparedStatementParams;
/**
* Holds cached mappings to charset converters to avoid static
* synchronization and at the same time save memory (each charset
* converter takes approx 65K of static data).
*/
private Map charsetConverterMap = new HashMap(CharsetMapping.JAVA_TO_MYSQL_CHARSET_MAP
.size());
/** A map of statements that have had setMaxRows() called on them */
private Map statementsUsingMaxRows;
/**
* The type map for UDTs (not implemented, but used by some third-party
* vendors, most notably IBM WebSphere)
*/
private Map typeMap;
/** The I/O abstraction interface (network conn to MySQL server */
private MysqlIO io = null;
/** Mutex */
private final Object mutex = new Object();
/** The map of server variables that we retrieve at connection init. */
private Map serverVariables = null;
/** The driver instance that created us */
private NonRegisteringDriver myDriver;
/** Properties for this connection specified by user */
private Properties props = null;
/** The database we're currently using (called Catalog in JDBC terms). */
private String database = null;
/** If we're doing unicode character conversions, what encoding do we use? */
private String encoding = null;
/** The hostname we're connected to */
private String host = null;
/** The JDBC URL we're using */
private String myURL = null;
/** What does MySQL call this encoding? */
private String mysqlEncodingName = null;
private String negativeInfinityRep = MysqlDefs.MIN_DOUBLE_VAL_STRING;
private String notANumberRep = MysqlDefs.NAN_VAL_STRING;
/** The password we used */
private String password = null;
private String positiveInfinityRep = MysqlDefs.MAX_DOUBLE_VAL_STRING;
/** Classname for socket factory */
private String socketFactoryClassName = null;
/** The user we're connected as */
private String user = null;
/** Where was the connection _explicitly_ closed by the application? */
private Throwable explicitCloseLocation;
/** If the connection was forced closed, why was it forced closed? */
private Throwable forcedCloseReason;
private TimeZone defaultTimeZone;
/** The timezone of the server */
private TimeZone serverTimezone = null;
/** Allow LOAD LOCAL INFILE (defaults to true) */
private boolean allowLoadLocalInfile = true;
/** Should we clear the input stream each query? */
private boolean alwaysClearStream = false;
/** Are we in autoCommit mode? */
private boolean autoCommit = true;
/** SHould we cache the parsing of prepared statements? */
private boolean cachePreparedStatements = false;
/** Should we capitalize mysql types */
private boolean capitalizeDBMDTypes = false;
/** Should we clobber streaming results on new queries, or issue an error? */
private boolean clobberStreamingResults = false;
/**
* Should we continue processing batch commands if one fails. The JDBC spec
* allows either way, so we let the user choose
*/
private boolean continueBatchOnError = true;
/** Should we do unicode character conversions? */
private boolean doUnicode = false;
/** Are we failed-over to a non-master host */
private boolean failedOver = false;
/** Does the server suuport isolation levels? */
private boolean hasIsolationLevels = false;
/** Does this version of MySQL support quoted identifiers? */
private boolean hasQuotedIdentifiers = false;
//
// This is for the high availability :) routines
//
private boolean highAvailability = false;
/** Ignore non-transactional table warning for rollback? */
private boolean ignoreNonTxTables = false;
/** Has this connection been closed? */
private boolean isClosed = true;
/** Should we tell MySQL that we're an interactive client? */
private boolean isInteractiveClient = false;
/** Is the server configured to use lower-case table names only? */
private boolean lowerCaseTableNames = false;
/** Has the max-rows setting been changed from the default? */
private boolean maxRowsChanged = false;
private boolean negativeInfinityRepIsClipped = true;
private boolean notANumberRepIsClipped = true;
/** Do we expose sensitive information in exception and error messages? */
private boolean paranoid = false;
/** Should we do 'extra' sanity checks? */
private boolean pedantic = false;
private boolean positiveInfinityRepIsClipped = true;
/** Should we retrieve 'info' messages from the server? */
private boolean readInfoMsg = false;
/** Are we in read-only mode? */
private boolean readOnly = false;
/**
* If autoReconnect == true, should we attempt to reconnect at transaction
* boundaries?
*/
private boolean reconnectAtTxEnd = false;
/** Do we relax the autoCommit semantics? (For enhydra, for example) */
private boolean relaxAutoCommit = false;
/** Do we need to correct endpoint rounding errors */
private boolean strictFloatingPoint = false;
/** Do we check all keys for updatable result sets? */
private boolean strictUpdates = true;
/** Are transactions supported by the MySQL server we are connected to? */
private boolean transactionsSupported = false;
/** Has ANSI_QUOTES been enabled on the server? */
private boolean useAnsiQuotes = false;
/** Should we use compression? */
private boolean useCompression = false;
/** Can we use the "ping" command rather than a query? */
private boolean useFastPing = false;
/** Should we tack on hostname in DBMD.getTable/ColumnPrivileges()? */
private boolean useHostsInPrivileges = true;
/** Should we use SSL? */
private boolean useSSL = false;
/**
* Should we use stream lengths in prepared statements? (true by default ==
* JDBC compliant)
*/
private boolean useStreamLengthsInPrepStmts = true;
/** Should we use timezone information? */
private boolean useTimezone = false;
/** Should we return PreparedStatements for UltraDev's stupid bug? */
private boolean useUltraDevWorkAround = false;
private boolean useUnbufferedInput = true;
private double initialTimeout = 2.0D;
/** How many hosts are in the host list? */
private int hostListSize = 0;
/** isolation level */
private int isolationLevel = java.sql.Connection.TRANSACTION_READ_COMMITTED;
/**
* The largest packet we can send (changed once we know what the server
* supports, we get this at connection init).
*/
private int maxAllowedPacket = 65536;
private int maxReconnects = 3;
/**
* The max rows that a result set can contain. Defaults to -1, which
* according to the JDBC spec means "all".
*/
private int maxRows = -1;
private int netBufferLength = 16384;
/** The port number we're connected to (defaults to 3306) */
private int port = 3306;
/**
* If prepared statement caching is enabled, what should the threshold
* length of the SQL to prepare should be in order to _not_ cache?
*/
private int preparedStatementCacheMaxSqlSize = 256;
/** If prepared statement caching is enabled, how many should we cache? */
private int preparedStatementCacheSize = 25;
/**
* How many queries should we wait before we try to re-connect to the
* master, when we are failing over to replicated hosts Defaults to 50
*/
private int queriesBeforeRetryMaster = 50;
/** What should we set the socket timeout to? */
private int socketTimeout = 0; // infinite
/** When did the last query finish? */
private long lastQueryFinishedTime = 0;
/** When did the master fail? */
private long masterFailTimeMillis = 0L;
/** Number of queries we've issued since the master failed */
private long queriesIssuedFailedOver = 0;
/**
* How many seconds should we wait before retrying to connect to the master
* if failed over? We fall back when either queriesBeforeRetryMaster or
* secondsBeforeRetryMaster is reached.
*/
private long secondsBeforeRetryMaster = 30L;
/**
* Creates a connection to a MySQL Server.
*
* @param host the hostname of the database server
* @param port the port number the server is listening on
* @param info a Properties[] list holding the user and password
* @param database the database to connect to
* @param url the URL of the connection
* @param d the Driver instantation of the connection
*
* @exception java.sql.SQLException if a database access error occurs
* @throws SQLException DOCUMENT ME!
*/
Connection(String host, int port, Properties info, String database,
String url, NonRegisteringDriver d) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { host, new Integer(port), info, database, url, d };
Debug.methodCall(this, "constructor", args);
}
this.defaultTimeZone = TimeZone.getDefault();
this.serverVariables = new HashMap();
if (host == null) {
this.host = "localhost";
hostList = new ArrayList();
hostList.add(this.host);
} else if (host.indexOf(",") != -1) {
// multiple hosts separated by commas (failover)
hostList = StringUtils.split(host, ",", true);
} else {
this.host = host;
hostList = new ArrayList();
hostList.add(this.host);
}
hostListSize = hostList.size();
this.port = port;
if (database == null) {
throw new SQLException("Malformed URL '" + url + "'.",
SQLError.SQL_STATE_GENERAL_ERROR);
}
this.database = database;
this.myURL = url;
this.myDriver = d;
this.user = info.getProperty("user");
this.password = info.getProperty("password");
if ((this.user == null) || this.user.equals("")) {
this.user = "nobody";
}
if (this.password == null) {
this.password = "";
}
this.props = info;
initializeDriverProperties(info);
if (Driver.DEBUG) {
System.out.println("Connect: " + this.user + " to " + this.database);
}
try {
createNewIO(false);
this.dbmd = new DatabaseMetaData(this, this.database);
} catch (java.sql.SQLException ex) {
cleanup(ex);
// don't clobber SQL exceptions
throw ex;
} catch (Exception ex) {
cleanup(ex);
StringBuffer mesg = new StringBuffer();
if (!useParanoidErrorMessages()) {
mesg.append("Cannot connect to MySQL server on ");
mesg.append(this.host);
mesg.append(":");
mesg.append(this.port);
mesg.append(".nn");
mesg.append("Make sure that there is a MySQL server ");
mesg.append("running on the machine/port you are trying ");
mesg.append(
"to connect to and that the machine this software is "
+ "running on ");
mesg.append("is able to connect to this host/port "
+ "(i.e. not firewalled). ");
mesg.append(
"Also make sure that the server has not been started "
+ "with the --skip-networking ");
mesg.append("flag.nn");
} else {
mesg.append("Unable to connect to database.");
}
mesg.append("Underlying exception: nn");
mesg.append(ex.getClass().getName());
throw new java.sql.SQLException(mesg.toString(),
SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE);
}
}
/**
* 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.
*
*
* Note: MySQL does not support transactions, so this method is a
* no-op.
*
*
* @param autoCommit - true enables auto-commit; false disables it
*
* @exception java.sql.SQLException if a database access error occurs
* @throws SQLException DOCUMENT ME!
*/
public void setAutoCommit(boolean autoCommit) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { new Boolean(autoCommit) };
Debug.methodCall(this, "setAutoCommit", args);
}
checkClosed();
if (this.transactionsSupported) {
// this internal value must be set first as failover depends on it
// being set to true to fail over (which is done by most
// app servers and connection pools at the end of
// a transaction), and the driver issues an implicit set
// based on this value when it (re)-connects to a server
// so the value holds across connections
//
this.autoCommit = autoCommit;
//
// This is to catch the 'edge' case of
// autoCommit going from true -> false
//
if ((this.highAvailability || this.failedOver) && !this.autoCommit) {
pingAndReconnect(true);
}
String sql = "SET autocommit=" + (autoCommit ? "1" : "0");
execSQL(sql, -1, this.database);
} else {
if ((autoCommit == false) && (this.relaxAutoCommit == false)) {
throw new SQLException("MySQL Versions Older than 3.23.15 "
+ "do not support transactions",
SQLError.SQL_STATE_DRIVER_NOT_CAPABLE);
} else {
this.autoCommit = autoCommit;
}
}
return;
}
/**
* gets the current auto-commit state
*
* @return Current state of the auto-commit mode
*
* @exception java.sql.SQLException (why?)
*
* @see setAutoCommit
*/
public boolean getAutoCommit() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "getAutoCommit", args);
Debug.returnValue(this, "getAutoCommit",
new Boolean(this.autoCommit));
}
return this.autoCommit;
}
/**
* 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
*
*
* Note: MySQL's notion of catalogs are individual databases.
*
*
* @param catalog the database for this connection to use
*
* @throws java.sql.SQLException if a database access error occurs
*/
public void setCatalog(String catalog) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { catalog };
Debug.methodCall(this, "setCatalog", args);
}
checkClosed();
String quotedId = this.dbmd.getIdentifierQuoteString();
if ((quotedId == null) || quotedId.equals(" ")) {
quotedId = "";
}
StringBuffer query = new StringBuffer("USE ");
query.append(quotedId);
query.append(catalog);
query.append(quotedId);
execSQL(query.toString(), -1, catalog);
this.database = catalog;
}
/**
* Return the connections current catalog name, or null if no catalog name
* is set, or we dont support catalogs.
*
*
* Note: MySQL's notion of catalogs are individual databases.
*
*
* @return the current catalog name or null
*
* @exception java.sql.SQLException if a database access error occurs
*/
public String getCatalog() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "getCatalog", args);
Debug.returnValue(this, "getCatalog", this.database);
}
return this.database;
}
/**
* Returns whether we clobber streaming results on new queries, or issue an
* error?
*
* @return true if we should implicitly close streaming result sets upon
* receiving a new query
*/
public boolean getClobberStreamingResults() {
return this.clobberStreamingResults;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean isClosed() {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "isClosed", args);
Debug.returnValue(this, "isClosed", new Boolean(this.isClosed));
}
return this.isClosed;
}
/**
* Returns the character encoding for this Connection
*
* @return the character encoding for this connection.
*/
public String getEncoding() {
return this.encoding;
}
/**
* @see Connection#setHoldability(int)
*/
public void setHoldability(int arg0) throws SQLException {
// do nothing
}
/**
* @see Connection#getHoldability()
*/
public int getHoldability() throws SQLException {
return ResultSet.CLOSE_CURSORS_AT_COMMIT;
}
/**
* NOT JDBC-Compliant, but clients can use this method to determine how
* long this connection has been idle. This time (reported in
* milliseconds) is updated once a query has completed.
*
* @return number of ms that this connection has been idle, 0 if the driver
* is busy retrieving results.
*/
public long getIdleFor() {
if (this.lastQueryFinishedTime == 0) {
return 0;
} else {
long now = System.currentTimeMillis();
long idleTime = now - this.lastQueryFinishedTime;
return idleTime;
}
}
/**
* Should we tell MySQL that we're an interactive client
*
* @return true if isInteractiveClient was set to true.
*/
public boolean isInteractiveClient() {
return isInteractiveClient;
}
/**
* 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 java.sql.SQLException if a database access error occurs
*/
public java.sql.DatabaseMetaData getMetaData() throws java.sql.SQLException {
checkClosed();
return new DatabaseMetaData(this, this.database);
}
/**
* DOCUMENT ME!
*
* @return
*/
public String getNegativeInfinityRep() {
return negativeInfinityRep;
}
/**
* DOCUMENT ME!
*
* @return
*/
public boolean isNegativeInfinityRepIsClipped() {
return negativeInfinityRepIsClipped;
}
/**
* DOCUMENT ME!
*
* @return
*/
public String getNotANumberRep() {
return notANumberRep;
}
/**
* DOCUMENT ME!
*
* @return
*/
public boolean isNotANumberRepIsClipped() {
return notANumberRepIsClipped;
}
/**
* DOCUMENT ME!
*
* @return
*/
public String getPositiveInfinityRep() {
return positiveInfinityRep;
}
/**
* DOCUMENT ME!
*
* @return
*/
public boolean isPositiveInfinityRepIsClipped() {
return positiveInfinityRepIsClipped;
}
/**
* Should the driver do profiling?
*
* @param flag set to true to enable profiling.
*
* @throws SQLException if the connection is closed.
*/
public void setProfileSql(boolean flag) throws SQLException {
// For re-connection
this.props.setProperty("profileSql", String.valueOf(flag));
getIO().setProfileSql(flag);
}
/**
* You can put a connection in read-only mode as a hint to enable database
* optimizations Note: setReadOnly cannot be called while in the
* middle of a transaction
*
* @param readOnly - true enables read-only mode; false disables it
*
* @exception java.sql.SQLException if a database access error occurs
*/
public void setReadOnly(boolean readOnly) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { new Boolean(readOnly) };
Debug.methodCall(this, "setReadOnly", args);
Debug.returnValue(this, "setReadOnly", new Boolean(readOnly));
}
checkClosed();
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 java.sql.SQLException if a database access error occurs
*/
public boolean isReadOnly() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "isReadOnly", args);
Debug.returnValue(this, "isReadOnly", new Boolean(this.readOnly));
}
return this.readOnly;
}
/**
* @see Connection#setSavepoint()
*/
public java.sql.Savepoint setSavepoint() throws SQLException {
throw new NotImplemented();
}
/**
* @see Connection#setSavepoint(String)
*/
public java.sql.Savepoint setSavepoint(String arg0)
throws SQLException {
throw new NotImplemented();
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public TimeZone getServerTimezone() {
return this.serverTimezone;
}
/**
* DOCUMENT ME!
*
* @param level DOCUMENT ME!
*
* @throws java.sql.SQLException DOCUMENT ME!
* @throws SQLException DOCUMENT ME!
*/
public void setTransactionIsolation(int level) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { new Integer(level) };
Debug.methodCall(this, "setTransactionIsolation", args);
}
checkClosed();
if (this.hasIsolationLevels) {
StringBuffer sql = new StringBuffer(
"SET SESSION TRANSACTION ISOLATION LEVEL ");
switch (level) {
case java.sql.Connection.TRANSACTION_NONE:
throw new SQLException("Transaction isolation level "
+ "NONE not supported by MySQL");
case java.sql.Connection.TRANSACTION_READ_COMMITTED:
sql.append("READ COMMITTED");
break;
case java.sql.Connection.TRANSACTION_READ_UNCOMMITTED:
sql.append("READ UNCOMMITTED");
break;
case java.sql.Connection.TRANSACTION_REPEATABLE_READ:
sql.append("REPEATABLE READ");
break;
case java.sql.Connection.TRANSACTION_SERIALIZABLE:
sql.append("SERIALIZABLE");
break;
default:
throw new SQLException("Unsupported transaction "
+ "isolation level '" + level + "'", "S1C00");
}
execSQL(sql.toString(), -1, this.database);
isolationLevel = level;
} else {
throw new java.sql.SQLException("Transaction Isolation Levels are "
+ "not supported on MySQL versions older than 3.23.36.", "S1C00");
}
}
/**
* Get this Connection's current transaction isolation mode.
*
* @return the current TRANSACTION_ mode value
*
* @exception java.sql.SQLException if a database access error occurs
* @throws SQLException DOCUMENT ME!
*/
public int getTransactionIsolation() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "getTransactionIsolation", args);
Debug.returnValue(this, "getTransactionIsolation",
new Integer(isolationLevel));
}
if (this.hasIsolationLevels) {
java.sql.Statement stmt = null;
java.sql.ResultSet rs = null;
try {
stmt = this.createStatement();
if (stmt.getMaxRows() != 0) {
stmt.setMaxRows(0);
}
String query = null;
if (this.io.versionMeetsMinimum(4, 0, 3)) {
query = "SHOW VARIABLES LIKE 'tx_isolation'";
} else {
query = "SHOW VARIABLES LIKE 'transaction_isolation'";
}
rs = stmt.executeQuery(query);
if (rs.next()) {
String s = rs.getString(2);
if (s != null) {
Integer intTI = (Integer) mapTransIsolationName2Value
.get(s);
if (intTI != null) {
return intTI.intValue();
}
}
throw new SQLException(
"Could not map transaction isolation '" + s
+ " to a valid JDBC level.",
SQLError.SQL_STATE_GENERAL_ERROR);
} else {
throw new SQLException("Could not retrieve transaction isolation level from server",
SQLError.SQL_STATE_GENERAL_ERROR);
}
} finally {
if (rs != null) {
try {
rs.close();
} catch (Exception ex) {
// ignore
}
rs = null;
}
if (stmt != null) {
try {
stmt.close();
} catch (Exception ex) {
// ignore
}
stmt = null;
}
}
}
return isolationLevel;
}
/**
* JDBC 2.0 Install a type-map object as the default type-map for this
* connection
*
* @param map the type mapping
*
* @throws SQLException if a database error occurs.
*/
public void setTypeMap(java.util.Map map) throws SQLException {
this.typeMap = map;
}
/**
* JDBC 2.0 Get the type-map object associated with this connection. By
* default, the map returned is empty.
*
* @return the type map
*
* @throws SQLException if a database error occurs
*/
public synchronized java.util.Map getTypeMap() throws SQLException {
if (this.typeMap == null) {
this.typeMap = new HashMap();
}
return this.typeMap;
}
/**
* The first warning reported by calls on this Connection is returned.
* Note: Sebsequent warnings will be changed to this
* java.sql.SQLWarning
*
* @return the first java.sql.SQLWarning or null
*
* @exception java.sql.SQLException if a database access error occurs
*/
public java.sql.SQLWarning getWarnings() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "getWarnings", args);
Debug.returnValue(this, "getWarnings", null);
}
return null;
}
/**
* Allow use of LOAD LOCAL INFILE?
*
* @return true if allowLoadLocalInfile was set to true.
*/
public boolean allowLoadLocalInfile() {
return this.allowLoadLocalInfile;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean capitalizeDBMDTypes() {
return this.capitalizeDBMDTypes;
}
/**
* After this call, getWarnings returns null until a new warning is
* reported for this connection.
*
* @exception java.sql.SQLException if a database access error occurs
*/
public void clearWarnings() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "clearWarnings", args);
}
// firstWarning = null;
}
/**
* 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)
* Note: A Connection is automatically closed when it is garbage
* collected. Certain fatal errors also result in a closed connection.
*
* @exception java.sql.SQLException if a database access error occurs
*/
public void close() throws java.sql.SQLException {
if (this.explicitCloseLocation == null) {
this.explicitCloseLocation = new Throwable();
}
realClose(true, true);
}
/**
* 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.
*
*
* Note: MySQL does not support transactions, so this method is a
* no-op.
*
*
* @exception java.sql.SQLException if a database access error occurs
* @throws SQLException DOCUMENT ME!
*
* @see setAutoCommit
*/
public void commit() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "commit", args);
}
checkClosed();
try {
// no-op if _relaxAutoCommit == true
if (this.autoCommit && !this.relaxAutoCommit) {
throw new SQLException("Can't call commit when autocommit=true",
SQLError.SQL_STATE_GENERAL_ERROR);
} else if (this.transactionsSupported) {
execSQL("commit", -1, this.database);
}
} finally {
if (this.reconnectAtTxEnd) {
pingAndReconnect(true);
}
}
return;
}
//--------------------------JDBC 2.0-----------------------------
/**
* JDBC 2.0 Same as createStatement() above, but allows the default result
* set type and result set concurrency type to be overridden.
*
* @param resultSetType a result set type, see ResultSet.TYPE_XXX
* @param resultSetConcurrency a concurrency type, see ResultSet.CONCUR_XXX
*
* @return a new Statement object
*
* @exception SQLException if a database-access error occurs.
*/
public java.sql.Statement createStatement(int resultSetType,
int resultSetConcurrency) throws SQLException {
checkClosed();
Statement stmt = new com.mysql.jdbc.Statement(this, this.database);
stmt.setResultSetType(resultSetType);
stmt.setResultSetConcurrency(resultSetConcurrency);
return stmt;
}
/**
* 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
*
* @throws SQLException passed through from the constructor
*/
public java.sql.Statement createStatement() throws SQLException {
return createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
java.sql.ResultSet.CONCUR_READ_ONLY);
}
/**
* @see Connection#createStatement(int, int, int)
*/
public java.sql.Statement createStatement(int resultSetType,
int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
if (this.pedantic) {
if (resultSetHoldability != ResultSet.HOLD_CURSORS_OVER_COMMIT) {
throw new SQLException("HOLD_CUSRORS_OVER_COMMIT is only supported holdability level",
SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
}
}
return createStatement(resultSetType, resultSetConcurrency);
}
/**
* DOCUMENT ME!
*
* @throws Throwable DOCUMENT ME!
*/
public void finalize() throws Throwable {
cleanup(null);
}
/**
* Is the server configured to use lower-case table names only?
*
* @return true if lower_case_table_names is 'on'
*/
public boolean lowerCaseTableNames() {
return this.lowerCaseTableNames;
}
/**
* 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 java.sql.SQLException if a database access error occurs
*/
public String nativeSQL(String sql) throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = { sql };
Debug.methodCall(this, "nativeSQL", args);
Debug.returnValue(this, "nativeSQL", sql);
}
return EscapeProcessor.escapeSQL(sql,
getIO().versionMeetsMinimum(4, 0, 2));
}
/**
* DOCUMENT ME!
*
* @param sql DOCUMENT ME!
*
* @return DOCUMENT ME!
*
* @throws java.sql.SQLException DOCUMENT ME!
*/
public java.sql.CallableStatement prepareCall(String sql)
throws java.sql.SQLException {
if (this.getUseUltraDevWorkAround()) {
return new UltraDevWorkAround(prepareStatement(sql));
} else {
throw new java.sql.SQLException("Callable statments not "
+ "supported.", "S1C00");
}
}
/**
* JDBC 2.0 Same as prepareCall() above, but allows the default result set
* type and result set concurrency type to be overridden.
*
* @param sql the SQL representing the callable statement
* @param resultSetType a result set type, see ResultSet.TYPE_XXX
* @param resultSetConcurrency a concurrency type, see ResultSet.CONCUR_XXX
*
* @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,
int resultSetType, int resultSetConcurrency) throws SQLException {
return prepareCall(sql);
}
/**
* @see Connection#prepareCall(String, int, int, int)
*/
public java.sql.CallableStatement prepareCall(String sql,
int resultSetType, int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
if (this.pedantic) {
if (resultSetHoldability != ResultSet.HOLD_CURSORS_OVER_COMMIT) {
throw new SQLException("HOLD_CUSRORS_OVER_COMMIT is only supported holdability level",
SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
}
}
throw new NotImplemented();
}
/**
* 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.
*
*
* Note: This method is optimized for handling parametric SQL
* statements that benefit from precompilation if the driver supports
* 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
* java.sql.SQLExceptions
*
*
*
* MySQL does not support precompilation of statements, so they are handled
* by the driver.
*
*
* @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 java.sql.SQLException if a database access error occurs.
*/
public java.sql.PreparedStatement prepareStatement(String sql)
throws java.sql.SQLException {
return prepareStatement(sql, java.sql.ResultSet.TYPE_FORWARD_ONLY,
java.sql.ResultSet.CONCUR_READ_ONLY);
}
/**
* JDBC 2.0 Same as prepareStatement() above, but allows the default result
* set type and result set concurrency type to be overridden.
*
* @param sql the SQL query containing place holders
* @param resultSetType a result set type, see ResultSet.TYPE_XXX
* @param resultSetConcurrency a concurrency type, see ResultSet.CONCUR_XXX
*
* @return a new PreparedStatement object containing the pre-compiled SQL
* statement
*
* @exception SQLException if a database-access error occurs.
*/
public synchronized java.sql.PreparedStatement prepareStatement(
String sql, int resultSetType, int resultSetConcurrency)
throws SQLException {
checkClosed();
PreparedStatement pStmt = null;
if (this.cachePreparedStatements) {
PreparedStatement.ParseInfo pStmtInfo = (PreparedStatement.ParseInfo) cachedPreparedStatementParams
.get(sql);
if (pStmtInfo == null) {
pStmt = new com.mysql.jdbc.PreparedStatement(this, sql,
this.database);
PreparedStatement.ParseInfo parseInfo = pStmt.getParseInfo();
if (parseInfo.statementLength < this.preparedStatementCacheMaxSqlSize) {
if (this.cachedPreparedStatementParams.size() >= 25) {
Iterator oldestIter = this.cachedPreparedStatementParams.keySet()
.iterator();
long lruTime = Long.MAX_VALUE;
String oldestSql = null;
while (oldestIter.hasNext()) {
String sqlKey = (String) oldestIter.next();
PreparedStatement.ParseInfo lruInfo = (PreparedStatement.ParseInfo) this.cachedPreparedStatementParams
.get(sqlKey);
if (lruInfo.lastUsed < lruTime) {
lruTime = lruInfo.lastUsed;
oldestSql = sqlKey;
}
}
if (oldestSql != null) {
this.cachedPreparedStatementParams.remove(oldestSql);
}
}
cachedPreparedStatementParams.put(sql, pStmt.getParseInfo());
}
} else {
pStmtInfo.lastUsed = System.currentTimeMillis();
pStmt = new com.mysql.jdbc.PreparedStatement(this, sql,
this.database, pStmtInfo);
}
} else {
pStmt = new com.mysql.jdbc.PreparedStatement(this, sql,
this.database);
}
//
// FIXME: Create warnings if can't create results of the given
// type or concurrency
//
pStmt.setResultSetType(resultSetType);
pStmt.setResultSetConcurrency(resultSetConcurrency);
return pStmt;
}
/**
* @see Connection#prepareStatement(String, int, int, int)
*/
public java.sql.PreparedStatement prepareStatement(String sql,
int resultSetType, int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
if (this.pedantic) {
if (resultSetHoldability != ResultSet.HOLD_CURSORS_OVER_COMMIT) {
throw new SQLException("HOLD_CUSRORS_OVER_COMMIT is only supported holdability level",
SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
}
}
return prepareStatement(sql, resultSetType, resultSetConcurrency);
}
/**
* @see Connection#prepareStatement(String, int)
*/
public java.sql.PreparedStatement prepareStatement(String sql,
int autoGenKeyIndex) throws SQLException {
java.sql.PreparedStatement pStmt = prepareStatement(sql);
((com.mysql.jdbc.PreparedStatement) pStmt).setRetrieveGeneratedKeys(autoGenKeyIndex == Statement.RETURN_GENERATED_KEYS);
return pStmt;
}
/**
* @see Connection#prepareStatement(String, int[])
*/
public java.sql.PreparedStatement prepareStatement(String sql,
int[] autoGenKeyIndexes) throws SQLException {
java.sql.PreparedStatement pStmt = prepareStatement(sql);
((com.mysql.jdbc.PreparedStatement) pStmt).setRetrieveGeneratedKeys((autoGenKeyIndexes != null)
&& (autoGenKeyIndexes.length > 0));
return pStmt;
}
/**
* @see Connection#prepareStatement(String, String[])
*/
public java.sql.PreparedStatement prepareStatement(String sql,
String[] autoGenKeyColNames) throws SQLException {
java.sql.PreparedStatement pStmt = prepareStatement(sql);
((com.mysql.jdbc.PreparedStatement) pStmt).setRetrieveGeneratedKeys((autoGenKeyColNames != null)
&& (autoGenKeyColNames.length > 0));
return pStmt;
}
/**
* @see Connection#releaseSavepoint(Savepoint)
*/
public void releaseSavepoint(Savepoint arg0) throws SQLException {
throw new NotImplemented();
}
/**
* The method rollback() drops all changes made since the previous
* commit/rollback and releases any database locks currently held by the
* Connection.
*
* @exception java.sql.SQLException if a database access error occurs
* @throws SQLException DOCUMENT ME!
*
* @see commit
*/
public void rollback() throws java.sql.SQLException {
if (Driver.TRACE) {
Object[] args = new Object[0];
Debug.methodCall(this, "rollback", args);
}
checkClosed();
try {
// no-op if _relaxAutoCommit == true
if (this.autoCommit && !this.relaxAutoCommit) {
throw new SQLException("Can't call rollback when autocommit=true",
SQLError.SQL_STATE_GENERAL_ERROR);
} else if (this.transactionsSupported) {
try {
rollbackNoChecks();
} catch (SQLException sqlEx) {
// We ignore non-transactional tables if told to do so
if (this.ignoreNonTxTables
&& (sqlEx.getErrorCode() != MysqlDefs.ER_WARNING_NOT_COMPLETE_ROLLBACK)) {
throw sqlEx;
}
}
}
} finally {
if (this.reconnectAtTxEnd) {
pingAndReconnect(true);
}
}
}
/**
* @see Connection#rollback(Savepoint)
*/
public void rollback(Savepoint arg0) throws SQLException {
throw new NotImplemented();
}
/**
* Used by MiniAdmin to shutdown a MySQL server
*
* @throws SQLException if the command can not be issued.
*/
public void shutdownServer() throws SQLException {
try {
this.io.sendCommand(MysqlDefs.SHUTDOWN, null, null);
} catch (Exception ex) {
throw new SQLException("Unhandled exception '" + ex.toString()
+ "'", SQLError.SQL_STATE_GENERAL_ERROR);
}
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean supportsIsolationLevel() {
return this.hasIsolationLevels;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean supportsQuotedIdentifiers() {
return this.hasQuotedIdentifiers;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean supportsTransactions() {
return this.transactionsSupported;
}
/**
* Should we use compression?
*
* @return should we use compression to communicate with the server?
*/
public boolean useCompression() {
return this.useCompression;
}
/**
* Returns the paranoidErrorMessages.
*
* @return boolean if we should be paranoid about error messages.
*/
public boolean useParanoidErrorMessages() {
return paranoid;
}
/**
* Should we use SSL?
*
* @return should we use SSL to communicate with the server?
*/
public boolean useSSL() {
return this.useSSL;
}
/**
* Should we enable work-arounds for floating point rounding errors in the
* server?
*
* @return should we use floating point work-arounds?
*/
public boolean useStrictFloatingPoint() {
return this.strictFloatingPoint;
}
/**
* Returns the strictUpdates value.
*
* @return boolean
*/
public boolean useStrictUpdates() {
return strictUpdates;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public boolean useTimezone() {
return this.useTimezone;
}
/**
* Should unicode character mapping be used ?
*
* @return should we use Unicode character mapping?
*/
public boolean useUnicode() {
return this.doUnicode;
}
/**
* DOCUMENT ME!
*
* @return Returns the defaultTimeZone.
*/
protected TimeZone getDefaultTimeZone() {
return defaultTimeZone;
}
/**
* Returns the IO channel to the server
*
* @return the IO channel to the server
*
* @throws SQLException if the connection is closed.
*/
protected MysqlIO getIO() throws SQLException {
if ((this.io == null) || this.isClosed) {
throw new SQLException("Operation not allowed on closed connection",
"08003");
}
return this.io;
}
protected int getNetWriteTimeout() {
String netWriteTimeoutStr = (String) this.serverVariables.get(
"net_write_timeout");
if (netWriteTimeoutStr != null) {
try {
return Integer.parseInt(netWriteTimeoutStr);
} catch (NumberFormatException nfe) {
return Integer.MAX_VALUE;
}
} else {
return Integer.MAX_VALUE;
}
}
/**
* Is this connection using unbuffered input?
*
* @return whether or not to use buffered input streams
*/
protected boolean isUsingUnbufferedInput() {
return this.useUnbufferedInput;
}
/**
* Creates an IO channel to the server
*
* @param isForReconnect is this request for a re-connect
*
* @return a new MysqlIO instance connected to a server
*
* @throws SQLException if a database access error occurs
*/
protected com.mysql.jdbc.MysqlIO createNewIO(boolean isForReconnect)
throws SQLException {
MysqlIO newIo = null;
if (!highAvailability && !this.failedOver) {
for (int hostIndex = 0; hostIndex < hostListSize; hostIndex++) {
try {
this.io = new MysqlIO(this.hostList.get(hostIndex).toString(),
this.port, this.socketFactoryClassName, this.props,
this, this.socketTimeout);
this.io.doHandshake(this.user, this.password, this.database);
this.isClosed = false;
if (this.database.length() != 0) {
this.io.sendCommand(MysqlDefs.INIT_DB, this.database,
null);
}
// save state from old connection
boolean autoCommit = getAutoCommit();
int oldIsolationLevel = getTransactionIsolation();
boolean oldReadOnly = isReadOnly();
String oldCatalog = getCatalog();
// Server properties might be different
// from previous connection, so initialize
// again...
initializePropsFromServer(this.props);
if (isForReconnect) {
// Restore state from old connection
setAutoCommit(autoCommit);
if (this.hasIsolationLevels) {
setTransactionIsolation(oldIsolationLevel);
}
setCatalog(oldCatalog);
}
if (hostIndex != 0) {
setFailedOverState();
} else {
this.failedOver = false;
if (hostListSize > 1) {
setReadOnly(false);
} else {
setReadOnly(oldReadOnly);
}
}
break; // low-level connection succeeded
} catch (SQLException sqlEx) {
if (this.io != null) {
this.io.forceClose();
}
String sqlState = sqlEx.getSQLState();
if ((sqlState == null)
|| !sqlState.equals(
SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE)) {
throw sqlEx;
}
if ((hostListSize - 1) == hostIndex) {
throw sqlEx;
}
} catch (Exception unknownException) {
if (this.io != null) {
this.io.forceClose();
}
if ((hostListSize - 1) == hostIndex) {
throw new SQLException(
"Unable to connect to any hosts due to exception: "
+ unknownException.toString(),
SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE);
}
}
}
} else {
double timeout = this.initialTimeout;
boolean connectionGood = false;
Exception connectionException = null;
for (int hostIndex = 0;
(hostIndex < hostListSize) && !connectionGood;
hostIndex++) {
for (int attemptCount = 0;
!connectionGood && (attemptCount < this.maxReconnects);
attemptCount++) {
try {
if (this.io != null) {
this.io.forceClose();
}
this.io = new MysqlIO(this.hostList.get(hostIndex)
.toString(),
this.port, this.socketFactoryClassName,
this.props, this, this.socketTimeout);
this.io.doHandshake(this.user, this.password,
this.database);
if (this.database.length() != 0) {
this.io.sendCommand(MysqlDefs.INIT_DB,
this.database, null);
}
ping();
this.isClosed = false;
// save state from old connection
boolean autoCommit = getAutoCommit();
int oldIsolationLevel = getTransactionIsolation();
boolean oldReadOnly = isReadOnly();
String oldCatalog = getCatalog();
// Server properties might be different
// from previous connection, so initialize
// again...
initializePropsFromServer(this.props);
if (isForReconnect) {
// Restore state from old connection
setAutoCommit(autoCommit);
if (this.hasIsolationLevels) {
setTransactionIsolation(oldIsolationLevel);
}
setCatalog(oldCatalog);
}
connectionGood = true;
if (hostIndex != 0) {
setFailedOverState();
} else {
this.failedOver = false;
if (hostListSize > 1) {
setReadOnly(false);
} else {
setReadOnly(oldReadOnly);
}
}
break;
} catch (Exception EEE) {
connectionException = EEE;
connectionGood = false;
}
if (!connectionGood) {
try {
Thread.sleep((long) timeout * 1000);
timeout = timeout * 2;
} catch (InterruptedException IE) {
;
}
}
}
if (!connectionGood) {
// We've really failed!
throw new SQLException(
"Server connection failure during transaction. Due to underlying exception: '"
+ connectionException + "'.nAttempted reconnect "
+ this.maxReconnects + " times. Giving up.",
SQLError.SQL_STATE_UNABLE_TO_CONNECT_TO_DATASOURCE);
}
}
}
if (paranoid && !highAvailability && (hostListSize <= 1)) {
password = null;
user = null;
}
return newIo;
}
/**
* Closes connection and frees resources.
*
* @param calledExplicitly is this being called from close()
* @param issueRollback should a rollback() be issued?
*
* @throws SQLException if an error occurs
*/
protected void realClose(boolean calledExplicitly, boolean issueRollback)
throws SQLException {
if (Driver.TRACE) {
Object[] args = new Object[] {
new Boolean(calledExplicitly), new Boolean(issueRollback)
};
Debug.methodCall(this, "realClose", args);
}
SQLException sqlEx = null;
if (!isClosed() && !getAutoCommit() && issueRollback) {
try {
rollback();
} catch (SQLException ex) {
sqlEx = ex;
}
}
if (this.io != null) {
try {
this.io.quit();
} catch (Exception e) {
;
}
this.io = null;
}
if (this.cachedPreparedStatementParams != null) {
this.cachedPreparedStatementParams.clear();
this.cachedPreparedStatementParams = null;
}
this.isClosed = true;
if (sqlEx != null) {
throw sqlEx;
}
}
/**
* Returns the locally mapped instance of a charset converter (to avoid
* overhead of static synchronization).
*
* @param javaEncodingName the encoding name to retrieve
*
* @return a character converter, or null if one couldn't be mapped.
*/
synchronized SingleByteCharsetConverter getCharsetConverter(
String javaEncodingName) {
SingleByteCharsetConverter converter = (SingleByteCharsetConverter) this.charsetConverterMap
.get(javaEncodingName);
if (converter == CHARSET_CONVERTER_NOT_AVAILABLE_MARKER) {
return null;
}
if (converter == null) {
try {
converter = SingleByteCharsetConverter.getInstance(javaEncodingName);
if (converter == null) {
this.charsetConverterMap.put(javaEncodingName,
CHARSET_CONVERTER_NOT_AVAILABLE_MARKER);
}
this.charsetConverterMap.put(javaEncodingName, converter);
} catch (UnsupportedEncodingException unsupEncEx) {
this.charsetConverterMap.put(javaEncodingName,
CHARSET_CONVERTER_NOT_AVAILABLE_MARKER);
converter = null;
}
}
return converter;
}
/**
* Returns the maximum packet size the MySQL server will accept
*
* @return DOCUMENT ME!
*/
int getMaxAllowedPacket() {
return this.maxAllowedPacket;
}
/**
* DOCUMENT ME!
*
* @return the max rows to return for statements (by default)
*/
int getMaxRows() {
return this.maxRows;
}
/**
* Returns the Mutex all queries are locked against
*
* @return DOCUMENT ME!
*
* @throws SQLException DOCUMENT ME!
*/
Object getMutex() throws SQLException {
if (this.io == null) {
throw new SQLException("Connection.close() has already been called. Invalid operation in this state.",
"08003");
}
return this.mutex;
}
/**
* Returns the packet buffer size the MySQL server reported upon connection