connection.java

开发MySql数据库的最新JDBC驱动。

			
			if (this.forcedClosedLocation != null) {
				messageBuf.append("\n\n");
				messageBuf
						.append(" at (stack trace):\n");
				messageBuf.append(Util
						.stackTraceToString(this.forcedClosedLocation));
			}

			if (this.forceClosedReason != null) {
				if (this.forcedClosedLocation != null) {
					messageBuf.append("\n\nDue ");
				} else {
					messageBuf.append("due ");
				}
				
				messageBuf.append("to underlying exception/error:\n");
				messageBuf.append(Util
						.stackTraceToString(this.forceClosedReason));
			}

			throw SQLError.createSQLException(messageBuf.toString(),
					SQLError.SQL_STATE_CONNECTION_NOT_OPEN);
		}
	}

	/**
	 * If useUnicode flag is set and explicit client character encoding isn't
	 * specified then assign encoding from server if any.
	 * 
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	private void checkServerEncoding() throws SQLException {
		if (getUseUnicode() && (getEncoding() != null)) {
			// spec'd by client, don't map
			return;
		}

		String serverEncoding = (String) this.serverVariables
				.get("character_set");

		if (serverEncoding == null) {
			// must be 4.1.1 or newer?
			serverEncoding = (String) this.serverVariables
					.get("character_set_server");
		}

		String mappedServerEncoding = null;

		if (serverEncoding != null) {
			mappedServerEncoding = CharsetMapping
					.getJavaEncodingForMysqlEncoding(serverEncoding
							.toUpperCase(Locale.ENGLISH), this);
		}

		//
		// First check if we can do the encoding ourselves
		//
		if (!getUseUnicode() && (mappedServerEncoding != null)) {
			SingleByteCharsetConverter converter = getCharsetConverter(mappedServerEncoding);

			if (converter != null) { // we know how to convert this ourselves
				setUseUnicode(true); // force the issue
				setEncoding(mappedServerEncoding);

				return;
			}
		}

		//
		// Now, try and find a Java I/O converter that can do
		// the encoding for us
		//
		if (serverEncoding != null) {
			if (mappedServerEncoding == null) {
				// We don't have a mapping for it, so try
				// and canonicalize the name....
				if (Character.isLowerCase(serverEncoding.charAt(0))) {
					char[] ach = serverEncoding.toCharArray();
					ach[0] = Character.toUpperCase(serverEncoding.charAt(0));
					setEncoding(new String(ach));
				}
			}

			if (mappedServerEncoding == null) {
				throw SQLError.createSQLException("Unknown character encoding on server '"
						+ serverEncoding
						+ "', use 'characterEncoding=' property "
						+ " to provide correct mapping",
						SQLError.SQL_STATE_INVALID_CONNECTION_ATTRIBUTE);
			}

			//
			// Attempt to use the encoding, and bail out if it
			// can't be used
			//
			try {
				"abc".getBytes(mappedServerEncoding);
				setEncoding(mappedServerEncoding);
				setUseUnicode(true);
			} catch (UnsupportedEncodingException UE) {
				throw SQLError.createSQLException(
						"The driver can not map the character encoding '"
								+ getEncoding()
								+ "' that your server is using "
								+ "to a character encoding your JVM understands. You "
								+ "can specify this mapping manually by adding \"useUnicode=true\" "
								+ "as well as \"characterEncoding=[an_encoding_your_jvm_understands]\" "
								+ "to your JDBC URL.", "0S100");
			}
		}
	}

	/**
	 * Set transaction isolation level to the value received from server if any.
	 * Is called by connectionInit(...)
	 * 
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	private void checkTransactionIsolationLevel() throws SQLException {
		String txIsolationName = null;

		if (versionMeetsMinimum(4, 0, 3)) {
			txIsolationName = "tx_isolation";
		} else {
			txIsolationName = "transaction_isolation";
		}

		String s = (String) this.serverVariables.get(txIsolationName);

		if (s != null) {
			Integer intTI = (Integer) mapTransIsolationNameToValue.get(s);

			if (intTI != null) {
				this.isolationLevel = intTI.intValue();
			}
		}
	}

	/**
	 * Destroys this connection and any underlying resources
	 * 
	 * @param fromWhere
	 *            DOCUMENT ME!
	 * @param whyCleanedUp
	 *            DOCUMENT ME!
	 */
	private void cleanup(Throwable whyCleanedUp) {
		try {
			if ((this.io != null) && !isClosed()) {
				realClose(false, false, false, whyCleanedUp);
			} else if (this.io != null) {
				this.io.forceClose();
			}
		} catch (SQLException sqlEx) {
			// ignore, we're going away.
			;
		}

		this.isClosed = true;
	}

	/**
	 * 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;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param sql
	 *            DOCUMENT ME!
	 * @return DOCUMENT ME!
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	public PreparedStatement clientPrepareStatement(String sql)
			throws SQLException {
		return clientPrepareStatement(sql,
				java.sql.ResultSet.TYPE_SCROLL_SENSITIVE,
				java.sql.ResultSet.CONCUR_READ_ONLY);
	}
	
	/**
	 * @see Connection#prepareStatement(String, int)
	 */
	public java.sql.PreparedStatement clientPrepareStatement(String sql,
			int autoGenKeyIndex) throws SQLException {
		java.sql.PreparedStatement pStmt = clientPrepareStatement(sql);

		((com.mysql.jdbc.PreparedStatement) pStmt)
				.setRetrieveGeneratedKeys(autoGenKeyIndex == java.sql.Statement.RETURN_GENERATED_KEYS);

		return pStmt;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param sql
	 *            DOCUMENT ME!
	 * @param resultSetType
	 *            DOCUMENT ME!
	 * @param resultSetConcurrency
	 *            DOCUMENT ME!
	 * @return DOCUMENT ME!
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	public PreparedStatement clientPrepareStatement(String sql,
			int resultSetType, int resultSetConcurrency) throws SQLException {
		return clientPrepareStatement(sql, resultSetType, resultSetConcurrency, true);
	}
	
	protected PreparedStatement clientPrepareStatement(String sql,
			int resultSetType, int resultSetConcurrency, 
			boolean processEscapeCodesIfNeeded) throws SQLException {
		checkClosed();

		String nativeSql = processEscapeCodesIfNeeded && getProcessEscapeCodesForPrepStmts() ? nativeSQL(sql): sql;
		
		PreparedStatement pStmt = null;

		if (getCachePreparedStatements()) {
			synchronized (this.cachedPreparedStatementParams) {
				PreparedStatement.ParseInfo pStmtInfo = (PreparedStatement.ParseInfo) this.cachedPreparedStatementParams
						.get(nativeSql);
	
				if (pStmtInfo == null) {
					pStmt = new com.mysql.jdbc.PreparedStatement(this, nativeSql,
							this.database);
	
					PreparedStatement.ParseInfo parseInfo = pStmt.getParseInfo();
	
					if (parseInfo.statementLength < getPreparedStatementCacheSqlLimit()) {
						if (this.cachedPreparedStatementParams.size() >= getPreparedStatementCacheSize()) {
							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);
							}
						}
	
						this.cachedPreparedStatementParams.put(nativeSql, pStmt
								.getParseInfo());
					}
				} else {
					pStmtInfo.lastUsed = System.currentTimeMillis();
					pStmt = new com.mysql.jdbc.PreparedStatement(this, nativeSql,
							this.database, pStmtInfo);
				}
			}
		} else {
			pStmt = new com.mysql.jdbc.PreparedStatement(this, nativeSql,
					this.database);
		}

		pStmt.setResultSetType(resultSetType);
		pStmt.setResultSetConcurrency(resultSetConcurrency);

		return pStmt;
	}

	
	public void close() throws SQLException {
		realClose(true, true, false, null);
	}

	/**
	 * Closes all currently open statements.
	 * 
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	private void closeAllOpenStatements() throws SQLException {
		SQLException postponedException = null;

		if (this.openStatements != null) {
			List currentlyOpenStatements = new ArrayList(); // we need this to
			// avoid
			// ConcurrentModificationEx

			for (Iterator iter = this.openStatements.keySet().iterator(); iter
					.hasNext();) {
				currentlyOpenStatements.add(iter.next());
			}

			int numStmts = currentlyOpenStatements.size();

			for (int i = 0; i < numStmts; i++) {
				Statement stmt = (Statement) currentlyOpenStatements.get(i);

				try {
					stmt.realClose(false, true);
				} catch (SQLException sqlEx) {
					postponedException = sqlEx; // throw it later, cleanup all
					// statements first
				}
			}

			if (postponedException != null) {
				throw postponedException;
			}
		}
	}

	private void closeStatement(java.sql.Statement stmt) {
		if (stmt != null) {
			try {
				stmt.close();
			} catch (SQLException sqlEx) {
				; // ignore
			}

			stmt = null;
		}
	}

	// --------------------------JDBC 2.0-----------------------------

	/**
	 * 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.
	 * <p>
	 * <b>Note:</b> MySQL does not support transactions, so this method is a
	 * no-op.
	 * </p>
	 * 
	 * @exception SQLException
	 *                if a database access error occurs
	 * @see setAutoCommit
	 */
	public void commit() throws SQLException {
		synchronized (getMutex()) {
			checkClosed();
	
			try {
				// no-op if _relaxAutoCommit == true
				if (this.autoCommit && !getRelaxAutoCommit()) {
					throw SQLError.createSQLException("Can't call commit when autocommit=true");
				} else if (this.transactionsSupported) {
					if (getUseLocalSessionState() && versionMeetsMinimum(5, 0, 0)) {
						if (!this.io.inTransactionOnServer()) {
							return; // effectively a no-op
						}
					}
					
					execSQL(null, "commit", -1, null,
							java.sql.ResultSet.TYPE_FORWARD_ONLY,
							java.sql.ResultSet.CONCUR_READ_ONLY, false,
							this.database, true,
							false);
				}
			} catch (SQLException sqlException) {
				if (SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE
						.equals(sqlException.getSQLState())) {
					throw SQLError.createSQLException(
							"Communications link failure during commit(). Transaction resolution unknown.",
							SQLError.SQL_STATE_TRANSACTION_RESOLUTION_UNKNOWN);
				}
	
				throw sqlException;
			} finally {
				this.needsPing = this.getReconnectAtTxEnd();
			}
	
			return;
		}
	}

	/**
	 * Configures client-side properties for character set information.
	 * 
	 * @throws SQLException
	 *             if unable to configure the specified character set.
	 */
	private void configureCharsetProperties() throws SQLException {
		if (getEncoding() != null) {
			// Attempt to use the encoding, and bail out if it
			// can't be used
			try {
				String testString = "abc";
				testString.getBytes(getEncoding());
			} catch (UnsupportedEncodingException UE) {
				// Try the MySQL character encoding, then....
				String oldEncoding = getEncoding();

				setEncoding(CharsetMapping.getJavaEncodingForMysqlEncoding(
						oldEncoding, this));

				if (getEncoding() == null) {
					throw SQLError.createSQLException(
							"Java does not support the MySQL character encoding "
									+ " " + "encoding '" + oldEncoding + "'.",
							SQLError.SQL_STATE_INVALID_CONNECTION_ATTRIBUTE);
				}

				try {
					String testString = "abc";
					testString.getBytes(getEncoding());
				} catch (UnsupportedEncodingException encodingEx) {
					throw SQLError.createSQLException("Unsupported character "
							+ "encoding '" + getEncoding() + "'.",
							SQLError.SQL_STATE_INVALID_CONNECTION_ATTRIBUTE);
				}
			}
		}
	}

	/**
	 * Sets up client character set for MySQL-4.1 and newer if the user This
	 * must be done before any further communication with the server!
	 * 
	 * @return true if this routine actually configured the client character
	 *         set, or false if the driver needs to use 'older' methods to
	 *         detect the character set, as it is connected to a MySQL server
	 *         older than 4.1.0
	 * @throws SQLException
	 *             if an exception happens while sending 'SET NAMES' to the
	 *             server, or the server sends character set information that
	 *             the client doesn't know about.
	 */
	private boolean configureClientCharacterSet() throws SQLException {
		String realJavaEncoding = getEncoding();
		boolean characterSetAlreadyConfigured = false;

		try {
			if (versionMeetsMinimum(4, 1, 0)) {
				characterSetAlreadyConfigured = true;

				setUseUnicode(true);

				configureCharsetProperties();
				realJavaEncoding = getEncoding(); // we need to do this again
				// to grab this for
				// versions > 4.1.0

				try {

					// Fault injection for testing server character set indices
		            
		            if (props != null && props.getProperty("com.mysql.jdbc.faultInjection.serverCharsetIndex") != null) {
		            	this.io.serverCharsetIndex = Integer.parseInt(
		            			props.getProperty(
		            					"com.mysql.jdbc.faultInjection.serverCharsetIndex"));	
		            }
		            
					String serverEncodingToSet = 
						CharsetMapping.INDEX_TO_CHARSET[this.io.serverCharsetIndex];
					
					if (serverEncodingToSet == null || serverEncodingToSet.length() == 0) {
						if (realJava