driver.java

一个OR Mapping 工具

package org.dbgen.support;

import java.sql.*;
import java.util.*;

/**
 * The Driver class is used for all database operations including insertion,
 * deletion, update, and retrieval of data objects.  An example is available
 * as follows:
 *
 * <PRE>
 * // Create the driver instance with a DbAccess object.
 * Driver driver = new Driver(new DbAccess(jdbcDriver, jdbcURL, username, password));
 * <P>
 * // Create a Customer object which was generated from DbGen.
 * Customer customer = new Customer("666-66-6666");
 * <P>
 * // Now retrieve the customer record.
 * Customer record = (Customer) driver.retrieve(customer);
 * <P>
 * // Try retrieve all customers with first name equals John order by last name.
 * Vector johns = driver.retrieve(customer, "FirstName = 'John'", "LastName");
 * for (int i = 0; i < johns.size(); i++) {
 *     System.out.println(johns);
 * }
 * <P>
 * // Insert a new customer into the database.
 * Customer johndoe = new Customer("777-77-7777", "John", "Doe", "213-213-1313");
 * driver.insert(johndoe);
 * <P>
 * // Update the record we inserted earlier to have new phone number.
 * johndoe.setPhoneNumber("213-213-0000");
 * driver.update(johndoe);
 * <P>
 * // Delete John Doe, please?
 * driver.delete(johndoe);
 * <P>
 * // Now see how many customer records are there with first name equals John.
 * int count = driver.getNumRows(customer, "FirstName = 'John'");
 * <P>
 * // See transactions(detail table rows) for John Doe.
 * Vector transactions = driver.retrieveDetails(customer, new Transaction());
 * </PRE>
 *
 */
public class Driver {
  org.dbgen.support.DbAccess fieldDBA = null;
  protected transient java.beans.PropertyChangeSupport propertyChange = new java.beans.PropertyChangeSupport(this);

  /**
   * Create a new driver instance.  Remember to set the DBA (DbAccess)
   * property before using the driver.
   */
  public Driver() {
  }

  /**
   * Create a new driver instance with the specified DbAccess object.
   *
   * @param dba A DbAccess object.
   */
  public Driver(org.dbgen.support.DbAccess dba) {
    setDBA(dba);
  }

  /**
   * Java bean property change support.
   */
  public synchronized void addPropertyChangeListener(java.beans.PropertyChangeListener listener) {
    propertyChange.addPropertyChangeListener(listener);
  }

  /**
   * Check the DBA handle.  If not available, just throw a SQLException.
   */
  private final void checkHandle()
    throws SQLException
  {
    if (getDBA() == null) {
      throw new SQLException();
    }
  }

  /**
   * Delete the specified data object.
   * @return The result value from the JDBC executeUpdate method.
   * @param data The data object that needs to be deleted from the database.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public int delete(Data data) throws SQLException
  {
    checkHandle();
    String sql = "DELETE FROM " + data.getTableName() + " WHERE " + data.getKeyConditions();

    return getDBA().executeUpdate(sql);
  }

  /**
   * Java bean property change support.
   */
  public void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
    propertyChange.firePropertyChange(propertyName, oldValue, newValue);
  }

  /**
   * Get the next batch of records available from the result set.
   * An instance of the data is needed in order to create
   * the right data objects to return.
   *
   * @return A vector of records from the result set.
   * @param data An instance of the expected data object type.
   * @param rs The ResultSet object that was created for the query.
   * @param max Maximum number of records to return in this batch.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public java.util.Vector getBatchRecords(org.dbgen.support.Data data, ResultSet rs, int max) throws SQLException {

    Vector vec = new Vector();
    int i;

    for (i = 0; i < max; i++)
    {
      Data obj = getNextRecord(data, rs);

      if (data != null)
      {
        vec.addElement(obj);
      }
      else
      {
      break;
      }
    }

    return i > 0 ? vec : null;
  }

  /**
   * Get the next batch of records available from the result set.
   * An instance of the data is needed in order to create
   * the right data objects to return.
   *
   * @return An array of records from the result set.
   * @param data An instance of the expected data object type.
   * @param rs The ResultSet object that was created for the query.
   * @param max Maximum number of records to return in this batch.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public Data[] getBatchRecordsAsArray(org.dbgen.support.Data data, ResultSet rs, int max) throws SQLException {
    return makeDataArrayFromVector(getBatchRecords(data, rs, max));
  }

  /**
   * Gets the DBA property (org.dbgen.support.DbAccess) value.
   * @return The DBA property value.
   * @see #setDBA
   */
  public org.dbgen.support.DbAccess getDBA() {
    /* Returns the DBA property value. */
    if (fieldDBA == null) {
      try {
        fieldDBA = new org.dbgen.support.DbAccess();
      } catch (Throwable exception) {
        System.err.println("Exception creating DBA property.");
      }
    };

    return fieldDBA;
  }

  /**
   * Get the next record available from the result set specified by the
   * ResultSet ID.  An instance of the data is needed in order to create
   * the right data objects to return.
   *
   * @return The next record from the result set.
   * @param data An instance of the expected data object.
   * @param rs The ResultSet object that was created for the query.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public org.dbgen.support.Data getNextRecord(org.dbgen.support.Data data, ResultSet rs) throws SQLException {
    if (rs == null)
    {
      return null;
    }
    else
    {
      if (rs.next())
      {
        return data.makeObject(rs);
      }

      getDBA().close(rs);

      return null;
    }
  }

  /**
   * Get number of rows for this table given a condition.
   * @return The number of rows for this table given a condition.
   * @param data An instance of the data object for this table.
   * @param condition A valid SQL condition string.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   * @exception ClassNotFoundException If the JDBC driver cannot be loaded.
   */
  public int getNumRows(org.dbgen.support.Data data, String condition) throws ClassNotFoundException, SQLException {
    checkHandle();
    String sql = "SELECT COUNT(*) FROM " + data.getTableName();

    if (condition != null && condition.length() > 0) {
      sql += " WHERE " + condition;
    }

    ResultSet rs = getDBA().executeQuery(sql);
    rs.next();
    int count = rs.getInt(1);
    getDBA().close(rs);

    return count;
  }

  /**
   * Insert a data object into the database table.
   * @return The result value from the JDBC executeUpdate call.
   * @param data An instance of the data object that needs to be inserted.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public int insert(Data data) throws SQLException
  {
    checkHandle();
    String sql = "INSERT INTO " + data.getTableName() + " VALUES (" + data.getInsertValues() + ")";

    return getDBA().executeUpdate(sql);
  }

  /**
   * Return a Data array from a Data vector.
   * @param vec java.util.Vector
   */
  private static Data[] makeDataArrayFromVector(Vector vec) {
    Data dataArray[] = new Data[vec.size()];

    for (int i = 0; i < vec.size(); i++)
    {
      dataArray[i] = (Data) vec.elementAt(i);
    }

    return dataArray;
  }

  /**
   * Execute a SQL query from the specified table. This method returns a
   * ResultSet object.  This ResultSet object is then used in the
   * getNextRecord(ResultSet rsid) method which retrieves individual record
   * from the result set.
   *
   * @return The corresponding ResultSet from the query.
   * @param data An instance of the data object for this table.
   * @param condition A valid SQL condition clause.
   * @param order A valid SQL order by clause.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public ResultSet query(org.dbgen.support.Data data, String condition, String order)
    throws SQLException
  {
    checkHandle();
    String sql = "SELECT * FROM " + data.getTableName();

    if (condition != null && condition.length() > 0) {
      sql += " WHERE " + condition;
    }

    if (order != null && order.length() > 0) {
      sql += " ORDER BY " + order;
    }

    return getDBA().executeQuery(sql);
  }

  /**
   * Java bean property change support.
   */
  public synchronized void removePropertyChangeListener(java.beans.PropertyChangeListener listener) {
    propertyChange.removePropertyChangeListener(listener);
  }

  /**
   * Retrieve a single record from the table.
   * @return An instance of the data object found in the table.
   * @param data An instance of data object for this table where the key fields has been set.
   * @exception SQLException When a SQL Exception occurred during the operation.
   * @exception RecordNotFoundException When the record is not found (incorrect primary key value?)
   */
  public org.dbgen.support.Data retrieve(org.dbgen.support.Data data) throws SQLException, RecordNotFoundException {

    ResultSet rs = query(data, data.getKeyConditions(), null);

    org.dbgen.support.Data obj = getNextRecord(data, rs);

    if (obj != null)
    {
      while (getNextRecord(data, rs) != null)
        ;
    }
    else
    {
      throw new RecordNotFoundException("Cannot find record for data " + data);
    }

    return obj;
  }

  /**
   * Retrieve a vector of data objects from the table.
   * @return A vector of data objects from the table that matches the given condition.
   * @param data An instance of data object for this table.
   * @param condition A valid SQL WHERE clause.
   * @param order A valid SQL ORDER BY clause.
   * @exception SQLException When a SQL Exception occurred during the operation.
   */
  public Vector retrieve(org.dbgen.support.Data data, String condition, String order) throws SQLException {

    Vector vec = new Vector();
    ResultSet rs = query(data, condition, order);
    Object obj;

    while ((obj = getNextRecord(data, rs)) != null)
    {
      vec.addElement(obj);
    }

    return vec.size() > 0 ? vec : null;
  }

  /**
   * Retrieve an array of data objects from the table.
   * @return An array of data objects from the table that matches the given condition.
   * @param data An instance of data object for this table.
   * @param condition A valid SQL WHERE clause.
   * @param order A valid SQL ORDER BY clause.
   * @exception SQLException When a SQL Exception occurred during the operation.
   */
  public org.dbgen.support.Data[] retrieveAsArray(org.dbgen.support.Data data, String condition, String order) throws SQLException {
    return makeDataArrayFromVector(retrieve(data, condition, order));
  }

  /**
   * Retrieve child record based on a 1-1 relationship defined in the parent Data class.
   *
   * @return A vector of data objects that is related to the parent data object.
   * @param parent An instance of the parent data object.
   * @param child An instance of the child data object.
   * @exception SQLException When a SQL Exception occurred during the operation.
   * @exception RecordNotFoundException When the record is not found (incorrect primary key value?)
   */
  public org.dbgen.support.Data retrieveDetail(org.dbgen.support.Data masterData, org.dbgen.support.Data foreignData )
    throws SQLException, RecordNotFoundException
  {

    ResultSet rs = query(foreignData, foreignData.getKeyConditions(masterData), null);

    org.dbgen.support.Data obj = getNextRecord(foreignData, rs);

    if (obj != null)
    {
      while (getNextRecord(foreignData, rs) != null)
        ;
    }
    else
    {
      throw new RecordNotFoundException("Cannot find record for data " + foreignData);
    }

    return obj;
  }

  /**
   * Retrieve child records based on a 1-n relationship defined in the parent Data class.
   *
   * @return A vector of data objects that is related to the parent data object.
   * @param parent An instance of the parent data object.
   * @param child An instance of the child data object.
   * @exception SQLException When a SQL Exception occurred during the operation.
   * @exception RecordNotFoundException When the record is not found (incorrect primary key value?)
   */
  public Vector retrieveDetails(org.dbgen.support.Data masterData, org.dbgen.support.Data foreignData)
    throws SQLException, RecordNotFoundException
  {
    Vector vec = new Vector();

    ResultSet rs = query(foreignData, foreignData.getKeyConditions(masterData), null);
    Object obj;

    while ((obj = getNextRecord(foreignData, rs)) != null)
    {
      vec.addElement(obj);
    }

    return vec.size() > 0 ? vec : null;
  }

  /**
   * Sets the DBA property (org.dbgen.support.DbAccess) value.
   * @param DBA The new value for the property.
   * @see #getDBA
   */
  public void setDBA(org.dbgen.support.DbAccess DBA) {
    /* Get the old property value for fire property change event. */
    org.dbgen.support.DbAccess oldValue = fieldDBA;

    /* Set the DBA property (attribute) to the new value. */
    fieldDBA = DBA;

    /* Fire (signal/notify) the DBA property change event. */
    firePropertyChange("DBA", oldValue, DBA);

    return;
  }

  /**
   * Update the data object to the table.
   * @return The result value from the JDBC executeUpdate method.
   * @param data An instance of data object that needs to be updated.
   * @exception java.sql.SQLException When a SQL Exception occurred during the operation.
   */
  public int update(Data data) throws SQLException
  {
    checkHandle();
    String sql = "UPDATE " + data.getTableName() + " SET " + data.getUpdateValues() + " WHERE " + data.getKeyConditions();

    return getDBA().executeUpdate(sql);
  }
}