database.java

监控大型网络的软件。能够自动发现拓扑结构

		}
	}

	/**
	 * <p> Execute the given query.  </p>
	 *
	 * @param statement The SQL query statement to exectute
	 * @param keepOpen If true, the resultset must be closed with the free() method
	 * @return the result of the query
	 */
	public static ResultSet query(String statement, boolean keepOpen) throws SQLException
	{
		// Try to execute. If we get a SocketException, wait and try again
		//boolean firstTry = true;
		while (true) {
			try {
				Statement st = getStatement(null, !keepOpen);
				ResultSet rs = st.executeQuery(statement);
				if (keepOpen) {
					statementMap.put(rs, st);
				}
				return rs;
			} catch (Exception e) {
				e.printStackTrace(System.err);
				if (e instanceof SQLException) {
					SQLException sqle = (SQLException)e;
					String msg = sqle.getMessage();
					if (msg.indexOf("broken the connection") < 0 &&
						msg.indexOf("SocketException") < 0 &&
						msg.indexOf("Connection is closed") < 0) {
						System.err.println("SQLException for update statement: " + statement);
						throw sqle;
					}
				}
				DBDescr db = getDBDescr(null);
				synchronized (db) {

					if (db.verifyConnection()) continue;
					//System.out.println("Verify failed...");
					if (db.reconnect()) continue;

					// That didn't work; log error
					String msg = e.getMessage();
					int idx;
					if (msg != null && (idx=msg.indexOf("Stack Trace")) >= 0) msg = msg.substring(0, idx-1);

					Log.e("DATABASE-QUERY", "Got Exception; database is probably down: " + msg);

					if (db.getReturnOnReconnectFail()) {
						throw new SQLException("Got Exception; database is probably down: " + msg);
					}

					while (!db.verifyConnection()) {
						try {
							Thread.sleep(DEFAULT_RECONNECT_WAIT_TIME);
							//System.out.println("Done sleeping, reconnect..");
							db.reconnect();
						} catch (InterruptedException ie) {
						}
					}
				}
			}
		}
	}

	/**
	 * <p> Begin a transaction. The database will not be changed until
	 * either commit() or rollback() is called.  </p>
	 */
	public static void beginTransaction() throws SQLException {
		try {
			getDBDescr(null).beginTransaction();
		} catch (SQLException e) {
			e.printStackTrace(System.err);
			throw e;
		}
	}

	/**
	 * <p> If a transaction is in progress, commit it, then go back to
	 * autocommit mode. Use beginTransaction() to start a new
	 * transaction.  </p>
	 */
	public static void commit() throws SQLException {
		//System.out.println("["+Integer.toHexString(Thread.currentThread().hashCode())+"] "+"Entering commit");
		try {
			getDBDescr(null).commit();
		} catch (SQLException e) {
			e.printStackTrace(System.err);
			throw e;
		}
	}

	/**
	 * <p> If a transaction is in progress, roll back any changes, then
	 * go back to autocommit mode. Use beginTransaction() to start a new
	 * transaction.  </p>
	 */
	public static void rollback() throws SQLException {
		try {
			getDBDescr(null).rollback();
		} catch (SQLException e) {
			e.printStackTrace(System.err);
			throw e;
		}
	}

	/**
	 * <p> Insert a row in the database and return the sequence number
	 * used for the row.  </p>
	 *
	 * <p> Currently this only works for the PostgreSQL database.  This
	 * method assumes that the first two elements of the fieldValues
	 * argument are the name of the id-column which is to be assigned
	 * the sequence number and a dummy value respectably.  </p>
	 *
	 * <p> If the given seqName is null, it is assumed to be
	 * "tablename_idfieldname_seq".  </p>
	 *
	 * @param table The name of the table in which the row is to be inserted
	 * @param fieldValues The names of columns and the values to be inserted
	 * @param seqName The name of the sequence from which to obtain the sequence number, or null
	 *
	 * @return the sequence number for the row
	 */
	public static String insert(String table, String[] fieldValues, String seqName) throws SQLException {
		if (seqName == null) seqName = table + "_" + fieldValues[0] + "_seq";

		Statement stUpdate = getUpdateStatement(null);
		ResultSet rs = stUpdate.executeQuery("SELECT nextval('" + seqName + "') AS seqnum");
		if (!rs.next()) throw new SQLException("Failed to get a sequence number from " + seqName);

		String seqNum = rs.getString("seqnum");
		fieldValues[1] = seqNum;

		insert(table, fieldValues);
		return seqNum;
	}

	/**
	 * <p> Insert a row in the specified table.  </p>
	 *
	 * <p> The fieldValues argument must contain an even number of
	 * elements, and each pair of consecutive elements must specify the
	 * name of the column and the value to be inserted in said column
	 * respectably.  </p>
	 *
	 * @param table The name of the table in which the row is to be inserted
	 * @param fieldValues The names of columns and the values to be inserted
	 *
	 * @return the number of inserted rows, which is always 1 
	 */
	public static int insert(String table, String[] fieldValues) throws SQLException
	{
		if ((fieldValues.length & 0x1) == 1)
			return -1;

		String query = "INSERT INTO " + table + " (";
		boolean first = true;
		for (int i = 0; i < fieldValues.length; i += 2) {
			if (fieldValues[i+1] != null) {
				if (!first) {
					query += ",";
				} else {
					first = false;
				}
				query += addSlashesStrict(fieldValues[i]);
			}
		}

		query += ") VALUES (";
		first = true;
		for (int i = 1; i < fieldValues.length; i += 2) {
			if (fieldValues[i] != null) {
				if (!first) {
					query += ",";
				} else {
					first = false;
				}

				boolean fnutt = true;
				if (fieldValues[i].equals("NOW()") ||
						fieldValues[i].equals("null") ||
						(fieldValues[i].startsWith("(") && !fieldValues[i].equals("(null)"))) {
					fnutt = false;
				}

				if (fnutt) {
					query += "'" + addSlashesStrict(fieldValues[i]) + "'";
				} else {
					query += fieldValues[i];
				}
			}
		}
		query += ")";
		return update(query);
	}

	/**
	 * <p> Update rows in the specified table.  </p>
	 *
	 * <p> The fieldValues argument must contain an even number of
	 * elements, and each pair of consecutive elements must specify the
	 * name of the column and the new value to be set in said column
	 * respectably.  </p>
	 *
	 * <p> The keyFieldValues specifies which rows to update; it must
	 * contain an even number of elements, and each pair of consecutive
	 * elements must specify the name of the column and the value said
	 * column must have for the row to be included in the update
	 * respectable.  </p>
	 *
	 * @param table The name of the table in which the row is to be inserted
	 * @param fieldValues The names of columns and the values to be inserted
	 *
	 * @return the number of updated rows.
	 */
	public static int update(String table, String[] fieldValues, String[] keyFieldValues) throws SQLException
	{
		if ((fieldValues.length & 0x1) == 1 || (keyFieldValues.length & 0x1) == 1)
			return -1;

		String query = "UPDATE " + table + " SET ";
		boolean noUpdate = true;
		boolean first = true;
		for (int i = 0; i < fieldValues.length; i += 2) {
			if (fieldValues[i+1] != null) {
				if (!first) {
					query += ",";
				} else {
					first = false;
				}

				noUpdate = false;
				boolean fnutt = true;
				if (fieldValues[i+1].equals("NOW()") ||
						fieldValues[i+1].equals("null") ||
						(fieldValues[i+1].startsWith("(") && !fieldValues[i+1].equals("(null)"))) {
					fnutt = false;
				}

				if (fnutt) {
					query += fieldValues[i] + "=" + "'" + addSlashesStrict(fieldValues[i+1]) + "'";
				} else {
					query += fieldValues[i] + "=" + fieldValues[i+1];
				}
			}
		}
		if (noUpdate) return 0;

		query += " WHERE ";
		for (int i = 0; i < keyFieldValues.length; i += 2) {
			if (i != 0) query += " AND ";

			query += keyFieldValues[i] + "='" + addSlashesStrict(keyFieldValues[i+1]) + "'";
		}
		return update(query);
	}

	/**
	 * <p> Execute the given statement, and return the number of rows
	 * updated.  </p>
	 *
	 * @param statement The statement to execute
	 * @return the number of rows updated
	 */
	public static int update(String statement) throws SQLException
	{
		while (true) {
			try {
				Statement stUpdate = getUpdateStatement(null);
				return stUpdate.executeUpdate(statement);
			} catch (Exception e) {
				e.printStackTrace(System.err);
				if (e instanceof SQLException) {
					SQLException sqle = (SQLException)e;
					String msg = sqle.getMessage();
					if (msg.indexOf("broken the connection") < 0 &&
						msg.indexOf("SocketException") < 0 &&
						msg.indexOf("Connection is closed") < 0) {
						System.err.println("SQLException for update statement: " + statement);
						throw sqle;
					}
				}
				DBDescr db = getDBDescr(null);
				synchronized (db) {

					if (db.verifyConnection()) continue;
					//System.out.println("Verify failed...");
					if (db.reconnect()) continue;

					// That didn't work; log error
					String msg = e.getMessage();
					int idx;
					if (msg != null && (idx=msg.indexOf("Stack Trace")) >= 0) msg = msg.substring(0, idx-1);

					Log.e("DATABASE-UPDATE", "Got Exception; database is probably down: " + msg);

					if (db.getReturnOnReconnectFail()) {
						throw new SQLException("Got Exception; database is probably down: " + msg);
					}

					while (!db.verifyConnection()) {
						try {
							Thread.sleep(DEFAULT_RECONNECT_WAIT_TIME);
							//System.out.println("Done sleeping, reconnect..");
							db.reconnect();
						} catch (InterruptedException ie) {
						}
					}
				}
			}
		}
	}

	/**
	 * <p> Return all columns from the current row in rs in a HashMap
	 * </p>
	 *
	 * @param rs ResultSet to fetch row from
	 * @param md Get column names from this object
	 * @return HashMap with all columns from the current row in rs
	 */
	public static HashMap getHashFromResultSet(ResultSet rs, ResultSetMetaData md) throws SQLException
	{
		HashMap hm = new HashMap();
		for (int i=md.getColumnCount(); i > 0; i--) {
			String s;
			if ((s=rs.getString(i)) != null)
				hm.put(md.getColumnName(i), s);
		}
		return hm;
	}

	/**
	 * <p> Make the given string "safe" (e.g. do not allow ( at the begining).
	 * \) </p>
	 *
	 * @param s The string to make safe
	 * @return a safe version of the string 
	 */
	public static String addSlashes(String s) {
		if (s == null) return null;
		if (s.startsWith("(")) s = "\\" + s;
		return addSlashesStrict(s);
	}

	/**
	 * <p> Escape any special characters in the given string (e.g. ' and
	 * \) </p>
	 *
	 * @param s The string to escape
	 * @return the string with special characters escaped
	 */
	private static String addSlashesStrict(String s) {
		if (s == null) return null;
		s = insertBefore(s, "\\", "\\");
		s = insertBefore(s, "'", "\\");
		return s;
	}

	private static String insertBefore(String tekst, String oldS, String newS) {
		if (tekst.indexOf(oldS) == -1)
			return tekst;
		StringBuffer b = new StringBuffer(tekst);
		int pos = -1 - newS.length();
		for (;;) {
			pos = b.toString().indexOf(oldS, pos + 1 + newS.length());
			if (pos == -1)
				break;
			b.insert(pos, newS);
		}
		return b.toString();
	}

}