connection.java

开发MySql数据库的最新JDBC驱动。

	
	private String origDatabaseToConnectTo;

	private String errorMessageEncoding = "Cp1252"; // to begin with, changes after we talk to the server

	private boolean usePlatformCharsetConverters;
	
	
	/**
	 * Creates a connection to a MySQL Server.
	 * 
	 * @param hostToConnectTo
	 *            the hostname of the database server
	 * @param portToConnectTo
	 *            the port number the server is listening on
	 * @param info
	 *            a Properties[] list holding the user and password
	 * @param databaseToConnectTo
	 *            the database to connect to
	 * @param url
	 *            the URL of the connection
	 * @param d
	 *            the Driver instantation of the connection
	 * @exception SQLException
	 *                if a database access error occurs
	 */
	Connection(String hostToConnectTo, int portToConnectTo, Properties info,
			String databaseToConnectTo, String url)
			throws SQLException {
		this.charsetToNumBytesMap = new HashMap();
		
		this.connectionCreationTimeMillis = System.currentTimeMillis();
		this.pointOfOrigin = new Throwable();
		
		// Stash away for later, used to clone this connection for Statement.cancel
		// and Statement.setQueryTimeout().
		//
		
		this.origHostToConnectTo = hostToConnectTo;
		this.origPortToConnectTo = portToConnectTo;
		this.origDatabaseToConnectTo = databaseToConnectTo;

		try {
			Blob.class.getMethod("truncate", new Class[] {Long.TYPE});
			
			this.isRunningOnJDK13 = false;
		} catch (NoSuchMethodException nsme) {
			this.isRunningOnJDK13 = true;
		}
		
		this.sessionCalendar = new GregorianCalendar();
		this.utcCalendar = new GregorianCalendar();
		this.utcCalendar.setTimeZone(TimeZone.getTimeZone("GMT"));
		
		//
		// Normally, this code would be in initializeDriverProperties,
		// but we need to do this as early as possible, so we can start
		// logging to the 'correct' place as early as possible...this.log
		// points to 'NullLogger' for every connection at startup to avoid
		// NPEs and the overhead of checking for NULL at every logging call.
		//
		// We will reset this to the configured logger during properties
		// initialization.
		//
		this.log = LogFactory.getLogger(getLogger(), LOGGER_INSTANCE_NAME);

		// We store this per-connection, due to static synchronization
		// issues in Java's built-in TimeZone class...
		this.defaultTimeZone = Util.getDefaultTimeZone();
		
		if ("GMT".equalsIgnoreCase(this.defaultTimeZone.getID())) {
			this.isClientTzUTC = true;
		} else {
			this.isClientTzUTC = false;
		}

		this.openStatements = new HashMap();
		this.serverVariables = new HashMap();
		this.hostList = new ArrayList();

		if (hostToConnectTo == null) {
			this.host = "localhost";
			this.hostList.add(this.host);
		} else if (hostToConnectTo.indexOf(",") != -1) {
			// multiple hosts separated by commas (failover)
			StringTokenizer hostTokenizer = new StringTokenizer(
					hostToConnectTo, ",", false);

			while (hostTokenizer.hasMoreTokens()) {
				this.hostList.add(hostTokenizer.nextToken().trim());
			}
		} else {
			this.host = hostToConnectTo;
			this.hostList.add(this.host);
		}

		this.hostListSize = this.hostList.size();
		this.port = portToConnectTo;

		if (databaseToConnectTo == null) {
			databaseToConnectTo = "";
		}

		this.database = databaseToConnectTo;
		this.myURL = url;
		this.user = info.getProperty(NonRegisteringDriver.USER_PROPERTY_KEY);
		this.password = info
				.getProperty(NonRegisteringDriver.PASSWORD_PROPERTY_KEY);

		if ((this.user == null) || this.user.equals("")) {
			this.user = "";
		}

		if (this.password == null) {
			this.password = "";
		}

		this.props = info;
		initializeDriverProperties(info);

		try {
			createNewIO(false);
			this.dbmd = new DatabaseMetaData(this, this.database);
		} catch (SQLException ex) {
			cleanup(ex);

			// don't clobber SQL exceptions
			throw ex;
		} catch (Exception ex) {
			cleanup(ex);

			StringBuffer mesg = new StringBuffer();

			if (getParanoid()) {
				mesg.append("Cannot connect to MySQL server on ");
				mesg.append(this.host);
				mesg.append(":");
				mesg.append(this.port);
				mesg.append(".\n\n");
				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.\n\n");
			} else {
				mesg.append("Unable to connect to database.");
			}

			mesg.append("Underlying exception: \n\n");
			mesg.append(ex.getClass().getName());

			if (!getParanoid()) {
				mesg.append(Util.stackTraceToString(ex));
			}

			throw SQLError.createSQLException(mesg.toString(),
					SQLError.SQL_STATE_COMMUNICATION_LINK_FAILURE);
		}
	}

	private void addToHistogram(int[] histogramCounts,
			long[] histogramBreakpoints, long value, int numberOfTimes,
			long currentLowerBound, long currentUpperBound) {
		if (histogramCounts == null) {
			createInitialHistogram(histogramBreakpoints,
					currentLowerBound, currentUpperBound);
		}

		for (int i = 0; i < HISTOGRAM_BUCKETS; i++) {
			if (histogramBreakpoints[i] >= value) {
				histogramCounts[i] += numberOfTimes;

				break;
			}
		}
	}

	private void addToPerformanceHistogram(long value, int numberOfTimes) {
		checkAndCreatePerformanceHistogram();

		addToHistogram(this.perfMetricsHistCounts,
				this.perfMetricsHistBreakpoints, value, numberOfTimes,
				this.shortestQueryTimeMs == Long.MAX_VALUE ? 0
						: this.shortestQueryTimeMs, this.longestQueryTimeMs);
	}

	private void addToTablesAccessedHistogram(long value, int numberOfTimes) {
		checkAndCreateTablesAccessedHistogram();

		addToHistogram(this.numTablesMetricsHistCounts,
				this.numTablesMetricsHistBreakpoints, value, numberOfTimes,
				this.minimumNumberTablesAccessed == Long.MAX_VALUE ? 0
						: this.minimumNumberTablesAccessed,
				this.maximumNumberTablesAccessed);
	}

	/**
	 * Builds the map needed for 4.1.0 and newer servers that maps field-level
	 * charset/collation info to a java character encoding name.
	 * 
	 * @throws SQLException
	 *             DOCUMENT ME!
	 */
	private void buildCollationMapping() throws SQLException {
		if (versionMeetsMinimum(4, 1, 0)) {

			TreeMap sortedCollationMap = null;

			if (getCacheServerConfiguration()) {
				synchronized (serverConfigByUrl) {
					sortedCollationMap = (TreeMap) serverCollationByUrl
							.get(getURL());
				}
			}

			com.mysql.jdbc.Statement stmt = null;
			com.mysql.jdbc.ResultSet results = null;

			try {
				if (sortedCollationMap == null) {
					sortedCollationMap = new TreeMap();

					stmt = (com.mysql.jdbc.Statement) createStatement();

					if (stmt.getMaxRows() != 0) {
						stmt.setMaxRows(0);
					}

					results = (com.mysql.jdbc.ResultSet) stmt
							.executeQuery("SHOW COLLATION");

					while (results.next()) {
						String charsetName = results.getString(2);
						Integer charsetIndex = new Integer(results.getInt(3));

						sortedCollationMap.put(charsetIndex, charsetName);
					}

					if (getCacheServerConfiguration()) {
						synchronized (serverConfigByUrl) {
							serverCollationByUrl.put(getURL(),
									sortedCollationMap);
						}
					}

				}

				// Now, merge with what we already know
				int highestIndex = ((Integer) sortedCollationMap.lastKey())
						.intValue();

				if (CharsetMapping.INDEX_TO_CHARSET.length > highestIndex) {
					highestIndex = CharsetMapping.INDEX_TO_CHARSET.length;
				}

				this.indexToCharsetMapping = new String[highestIndex + 1];

				for (int i = 0; i < CharsetMapping.INDEX_TO_CHARSET.length; i++) {
					this.indexToCharsetMapping[i] = CharsetMapping.INDEX_TO_CHARSET[i];
				}

				for (Iterator indexIter = sortedCollationMap.entrySet()
						.iterator(); indexIter.hasNext();) {
					Map.Entry indexEntry = (Map.Entry) indexIter.next();

					String mysqlCharsetName = (String) indexEntry.getValue();

					this.indexToCharsetMapping[((Integer) indexEntry.getKey())
							.intValue()] = CharsetMapping
							.getJavaEncodingForMysqlEncoding(mysqlCharsetName,
									this);
				}
			} catch (java.sql.SQLException e) {
				throw e;
			} finally {
				if (results != null) {
					try {
						results.close();
					} catch (java.sql.SQLException sqlE) {
						;
					}
				}

				if (stmt != null) {
					try {
						stmt.close();
					} catch (java.sql.SQLException sqlE) {
						;
					}
				}
			}
		} else {
			// Safety, we already do this as an initializer, but this makes
			// the intent more clear
			this.indexToCharsetMapping = CharsetMapping.INDEX_TO_CHARSET;
		}
	}
	
	private boolean canHandleAsServerPreparedStatement(String sql) 
		throws SQLException {
		if (sql == null || sql.length() == 0) {
			return true;
		}

		if (getCachePreparedStatements()) {
			synchronized (this.serverSideStatementCheckCache) {
				Boolean flag = (Boolean)this.serverSideStatementCheckCache.get(sql);
				
				if (flag != null) {
					return flag.booleanValue();
				}
					
				boolean canHandle = canHandleAsServerPreparedStatementNoCache(sql);
				
				if (sql.length() < getPreparedStatementCacheSqlLimit()) {
					this.serverSideStatementCheckCache.put(sql, 
							canHandle ? Boolean.TRUE : Boolean.FALSE);
				}
					
				return canHandle;
			}
		}
		
		return canHandleAsServerPreparedStatementNoCache(sql);
	}

	private boolean canHandleAsServerPreparedStatementNoCache(String sql) 
		throws SQLException {
		
		// Can't use server-side prepare for CALL
		if (StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql, "CALL")) {
			return false;
		}
		
		boolean canHandleAsStatement = true;
		
		if (!versionMeetsMinimum(5, 0, 7) && 
				(StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql, "SELECT")
				|| StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,
						"DELETE")
				|| StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,
						"INSERT")
				|| StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,
						"UPDATE")
				|| StringUtils.startsWithIgnoreCaseAndNonAlphaNumeric(sql,
						"REPLACE"))) {

			// check for limit ?[,?]

			/*
			 * The grammar for this (from the server) is: ULONG_NUM | ULONG_NUM
			 * ',' ULONG_NUM | ULONG_NUM OFFSET_SYM ULONG_NUM
			 */

			int currentPos = 0;
			int statementLength = sql.length();
			int lastPosToLook = statementLength - 7; // "LIMIT ".length()
			boolean allowBackslashEscapes = !this.noBackslashEscapes;
			char quoteChar = this.useAnsiQuotes ? '"' : '\'';
			boolean foundLimitWithPlaceholder = false;

			while (currentPos < lastPosToLook) {
				int limitStart = StringUtils.indexOfIgnoreCaseRespectQuotes(
						currentPos, sql, "LIMIT ", quoteChar,
						allowBackslashEscapes);

				if (limitStart == -1) {
					break;
				}

				currentPos = limitStart + 7;

				while (currentPos < statementLength) {
					char c = sql.charAt(currentPos);

					//
					// Have we reached the end
					// of what can be in a LIMIT clause?
					//

					if (!Character.isDigit(c) && !Character.isWhitespace(c)
							&& c != ',' && c != '?') {
						break;
					}

					if (c == '?') {
						foundLimitWithPlaceholder = true;
						break;
					}

					currentPos++;
				}
			}

			canHandleAsStatement = !foundLimitWithPlaceholder;
		} else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "CREATE TABLE")) {
			canHandleAsStatement = false;
		} else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "DO")) {
			canHandleAsStatement = false;
		} else if (StringUtils.startsWithIgnoreCaseAndWs(sql, "SET")) {
			canHandleAsStatement = false;
		}

		
		
		return canHandleAsStatement;
	}

	/**
	 * Changes the user on this connection by performing a re-authentication. If
	 * authentication fails, the connection will remain under the context of the
	 * current user.
	 * 
	 * @param userName
	 *            the username to authenticate with
	 * @param newPassword
	 *            the password to authenticate with
	 * @throws SQLException
	 *             if authentication fails, or some other error occurs while
	 *             performing the command.
	 */
	public void changeUser(String userName, String newPassword)
			throws SQLException {
		if ((userName == null) || userName.equals("")) {
			userName = "";
		}

		if (newPassword == null) {
			newPassword = "";
		}

		this.io.changeUser(userName, newPassword, this.database);
		this.user = userName;
		this.password = newPassword;

		if (versionMeetsMinimum(4, 1, 0)) {
			configureClientCharacterSet();
		}
		
		setupServerForTruncationChecks();
	}

	private void checkAndCreatePerformanceHistogram() {
		if (this.perfMetricsHistCounts == null) {
			this.perfMetricsHistCounts = new int[HISTOGRAM_BUCKETS];
		}

		if (this.perfMetricsHistBreakpoints == null) {
			this.perfMetricsHistBreakpoints = new long[HISTOGRAM_BUCKETS];
		}
	}

	private void checkAndCreateTablesAccessedHistogram() {
		if (this.numTablesMetricsHistCounts == null) {
			this.numTablesMetricsHistCounts = new int[HISTOGRAM_BUCKETS];
		}

		if (this.numTablesMetricsHistBreakpoints == null) {
			this.numTablesMetricsHistBreakpoints = new long[HISTOGRAM_BUCKETS];
		}
	}

	private void checkClosed() throws SQLException {
		if (this.isClosed) {
			StringBuffer messageBuf = new StringBuffer(
					"No operations allowed after connection closed.");

			if (this.forcedClosedLocation != null || this.forceClosedReason != null) {
				messageBuf
				.append("Connection was implicitly closed ");
			}