jdbchelper.java.craig

把java对象映射成数据库表中的一条记录

   * @return a value of type 'int'
   * @exception SQLException if an error occurs
   */
  public int executeUpdate(String sqlString)
          throws ClassNotFoundException,
          InstantiationException,
          IllegalAccessException,
          SQLException
    {
    Statement statement;

    this.validateConnection();
    if (LOG.isDebugEnabled())
        {
        LOG.debug("[" + sqlString + "]");
        }

    if (i_statement == null)
        {
        i_statement = i_connection.createStatement();
        }
    else if (!i_reuseStatement)
        {
        i_statement.close();
        i_statement = i_connection.createStatement();
        }

    int resultCount = i_statement.executeUpdate(sqlString);
    if (LOG.isDebugEnabled())
        {
        LOG.debug(resultCount + " rows impacted by sql statement.");
        }
    return resultCount;
    }


  /**
   * Execute an update/insert/delete on a PreparedStatement
   *
   * @param sqlString a value of type 'String'
   * @return either the row count for INSERT, UPDATE or DELETE statements;
   * or 0 for SQL statements that return nothing
   * @exception SQLException if an error occurs
   */
  public int executeUpdate(PreparedStatement stmt)
          throws ClassNotFoundException,
          InstantiationException,
          IllegalAccessException,
          SQLException
    {
    Statement statement;

    this.validateConnection();
    if (LOG.isDebugEnabled())
        {
        LOG.debug("[" + stmt + "]");
        }

    if (i_statement != null)
        { // The connection is being reused, but not the statement
        i_statement.close();
        }
    i_statement = stmt;

    int resultCount = stmt.executeUpdate();
    if (LOG.isDebugEnabled())
        {
        LOG.debug(resultCount + " rows impacted by prepared sql statement.");
        }
    return resultCount;
    }


  /**
   * Make sure the connection exists and is open.
   */
  private void validateConnection()
          throws ClassNotFoundException,
          InstantiationException,
          IllegalAccessException,
          SQLException
    {
    if ((i_connection == null)
        || i_connection.isClosed())
        {
        i_statement = null;
        i_resultSet = null;
        Class.forName (i_driverClass).newInstance();
        i_connection = DriverManager.getConnection (i_url, i_properties);
        i_connection.setAutoCommit(this.getShouldAutoCommit());
        }
    }


  /**
   * Assume we have a connection.  If it is closed we don't want to open it
   * by calling validateConnection().
   *
   * @return a value of type 'boolean'
   */
  public boolean isConnectionClosed()
          throws SQLException
    {
    return i_connection.isClosed();
    }


  /**
   * Return the current Connection.  This was added to allow users to
   * bypass the executeQuery() method.  i.e. to use a PreparedStatement
   * instead of a Statement, etc.
   *
   * @return a value of type 'Connection'
   */
  public Connection getConnection()
          throws ClassNotFoundException,
          InstantiationException,
          IllegalAccessException,
          SQLException
    {
    this.validateConnection();
    return i_connection;
    }


  /**
   * Return the current ResultSet
   *
   * @return a value of type 'ResultSet'
   */
  public ResultSet getResultSet()
    {
    return i_resultSet;
    }


  /**
   * Move the cursor to the next row in the result set.
   *
   * @return true if the new current row is valid; false if there are no
   *              more rows.
   * @exception SQLException if a database access error occurs
   */
  public boolean next()
          throws SQLException
    {
    return i_resultSet.next();
    }


  /**
   * Close the result set, statement, and connection.
   * If the connection is from a pool driver, it is returned to the pool.
   *
   * @exception SQLException if a database access error occurs
   */
  public void close()
          throws SQLException
    {
    if (i_isInsideTransaction)
        {
        LOG.debug("JDBCHelper.close() not executed--inside transaction.");
        return;
        }
    else
        {
        LOG.debug("JDBCHelper.close()");
        }

    if ((i_connection != null)
        &&  !i_connection.isClosed() )
        {
        try
            {
            if (this.getShouldCommitOnClose() )
                {
                i_connection.commit();
                }
            }
        finally
            {
            // If this connection came from a driver that is a pool,
            // then this will return the connection to the pool.
            // Else it will be freeing the connection (as it should).
            i_connection.close();
            }
        }
    } // close()


  /**
   * Commit the transaction.
   *
   * @exception SQLException if a database access error occurs
   */
  public void commit()
          throws SQLException
    {
    if (i_isInsideTransaction)
        {
        LOG.debug("JDBCHelper.commit() not executed -- inside a transaction");
        }
    else
        {
        LOG.debug("JDBCHelper.commit()");
        i_connection.commit();
        }
    }


  /**
   * Rollback the transaction.
   *
   * @exception SQLException if a database access error occurs
   */
  public void rollback()
          throws SQLException
    {
    LOG.info("JDBCHelper.rollback()");
    i_isInsideTransaction = false;
    i_connection.rollback();
    }


  /**
   * Calling this method tells JDBCHelper to ignore commit() messages and
   * close() messages until endTransaction() is called.  rollback() messages
   * are *not* ignored.
   */
  public void beginTransaction()
          throws ClassNotFoundException,
          InstantiationException,
          IllegalAccessException,
          SQLException
    {
    LOG.debug("JDBCHelper.beginTransaction()");
    this.validateConnection();
    i_isInsideTransaction = true;
    }


  /**
   * This method turns off the isInsideTransaction flag and commits and
   * closes the database.
   *
   * @exception SQLException if an error occurs
   */
  public void endTransaction()
          throws SQLException
    {
    LOG.debug("JDBCHelper.endTransaction()");
    i_isInsideTransaction = false;
    this.commit();
    this.close();
    }


  /**
   * Return the name of the column that was unsuccessfully accessed.
   *
   * @return a value of type 'String'
   */
  public String getColumnName()
    {
    return i_columnName;
    }


  /**
   * Return the SQL string that was last executed.
   *
   * @return a value of type 'String'
   */
  public String getSQLString()
    {
    return i_sqlString;
    }


  /**
   * Print out the column names returned in the result set.
   * This can only be done if the resultSet is not null.
   */
  public void printColumnNames()
    {
    ResultSetMetaData metaData = null;
    try
        {
        metaData = i_resultSet.getMetaData();
        System.out.print("Column Names: ");
        for (int i=1; i<=metaData.getColumnCount(); i++)
            {
            System.out.print(metaData.getColumnName(i));
            if (i != metaData.getColumnCount())
                {
                System.out.print(", ");
                } // if
            } // for
        System.out.println(); // add a carriage return
        }
    catch (SQLException e)
        {
        System.out.println(
            "SQLException occurred in JDBCHelper.printMetaData(): " + e);
        }
    } // printColumnNames()


  /**
   * Return a copy of myself without a database connection.
   *
   * @return a value of type 'Object'
   */
  public Object clone()
          throws CloneNotSupportedException
    {
    JDBCHelper clone = (JDBCHelper) super.clone();
    clone.i_statement = null;
    clone.i_resultSet = null;
    clone.i_connection = null;
    return clone;
    }



  /* ==============  Column Value Accessors  ================= */


  /**
   * Get whatever type of object is in the given column.
   * If the column has a null, this will return false.
   * @param column a value of type 'String'
   * @return a value of type 'Object'
   */
  public Object getObject(String column)
          throws SQLException
    {
    i_columnName = column;
    Object returnValue = i_resultSet.getObject(column);
    i_columnName = EMPTY_STRING;
    return returnValue;
    }


  /**
   * Get whatever type of object is in the given column.
   * If the column has a null, this will return false.
   * @param column a value of type 'int'
   * @return a value of type 'Object'
   */
  public Object getObject(int column)
          throws SQLException
    {
    i_columnIndex = column;
    Object returnValue = i_resultSet.getObject(column);
    i_columnIndex = 0;
    return returnValue;
    }


  /**
   * Calls the getBoolean() method on the ResultSet.
   * If the column has a null, this will return false.
   * @param column a value of type 'String'
   * @return a value of type 'boolean'
   * @exception SQLException if column is not found
   */
  public boolean getboolean(String column)
          throws SQLException
    {
    i_columnName = column;
    boolean returnValue = i_resultSet.getBoolean(column);
    i_columnName = EMPTY_STRING;
    return returnValue;
    }


  /**
   * Calls the getboolean() method on the ResultSet.
   * If the column has a null, this will return false.
   * @param column a value of type 'int'
   * @return a value of type 'boolean'
   * @exception SQLException if column is not found
   */
  public boolean getboolean(int column)
          throws SQLException
    {
    i_columnIndex = column;
    boolean returnValue = i_resultSet.getBoolean(column);
    i_columnIndex = 0;
    return returnValue;
    }


  /**
   * Calls the getBoolean() method on the ResultSet and wraps the boolean in
   * a Boolean.  If the column has a null, this will return a null.
   * @param column a value of type 'String'
   * @return a value of type 'Boolean'
   * @exception SQLException if column is not found
   */
  public Boolean getBoolean(String column)
          throws SQLException
    {
    i_columnName = column;
    Boolean returnValue = new Boolean(i_resultSet.getBoolean(column));
    i_columnName = EMPTY_STRING;
    return returnValue;
    }


  /**
   * Calls the getBoolean() method on the ResultSet and wraps the boolean in
   * a Boolean.  If the column has a null, this will return a null.
   * @param column a value of type 'int'
   * @return a value of type 'Boolean'
   * @exception SQLException if column is not found
   */
  public Boolean getBoolean(int column)
          throws SQLException
    {
    i_columnIndex = column;
    Boolean returnValue = new Boolean(i_resultSet.getBoolean(column));
    i_columnIndex = 0;
    return returnValue;
    }


  /**
   * Calls the getString() method on the ResultSet and trims the result.
   * If the column has a null, this will return a null.
   * @param column a value of type 'String'
   * @return a value of type 'String'
   * @exception SQLException if column is not found
   * @see #getRawString
   */
  public String getString(String column)
          throws SQLException
    {
    i_columnName = column;
    String result = i_resultSet.getString(column);

    if (result != null)
        {
        result = result.trim();
        }

    i_columnName = EMPTY_STRING;
    return result;
    }


  /**
   * Calls the getString() method on the ResultSet and trims the result.
   * If the column has a null, this will return a null.
   * @param column a value of type 'int'
   * @return a value of type 'String'
   * @exception SQLException if column is not found
   * @see #getRawString
   */
  public String getString(int column)
          throws SQLException
    {
    i_columnIndex = column;
    String result = i_resultSet.getString(column);

    if (result != null)
        {
        result = result.trim();
        }

    i_columnIndex = 0;
    return result;
    }


  /**
   * Calls the getString() method on the ResultSet.
   * If the column has a null, this will return a null.
   * @param column a value of type 'String'
   * @return a value of type 'String'
   * @exception SQLException if column is not found
   */
  public String getRawString(String column)
          throws SQLException
    {
    i_columnName = column;
    String returnValue = i_resultSet.getString(column);
    i_columnName = EMPTY_STRING;
    return returnValue;
    }


  /**
   * Calls the getString() method on the ResultSet.
   * If the column has a null, this will return a null.
   * @param column a value of type 'int'
   * @return a value of type 'String'
   * @exception SQLException if column is not found
   */
  public String getRawString(int column)
          throws SQLException
    {
    i_columnIndex = column;
    String returnValue = i_resultSet.getString(column);
    i_columnIndex = 0;
    return returnValue;
    }


  /**
   * Calls the getTimestamp() method on the ResultSet.
   * If the column has a null, this will return a null.
   * @param column a value of type 'String'
   * @return a value of type 'Date'
   * @exception SQLException if column is not found
   */
  public Timestamp getTimestamp(String column)
          throws SQLException
    {
    i_columnName = column;
    Timestamp returnValue =  i_resultSet.getTimestamp(column);
    i_columnName = EMPTY_STRING;
    return returnValue;
    }


  /**
   * Calls the getTimestamp() method on the ResultSet.
   * If the column has a null, this will return a null.
   * @param column a value of type 'int'
   * @return a value of type 'Date'
   * @exception SQLException if column is not found
   */
  public Timestamp getTimestamp(int column)
          throws SQLException