resultsettablemodel.java~6~

许多开发者和用户都在寻找Java程序中访问数据库的便捷方法。由于Java是一个健壮

package javadatabase;

import java.sql.*;
import java.util.*;
import javax.swing.table.*;

public class ResultSetTableModel {
  private Connection connection;
  private Statement statement;
  private ResultSet resultSet;
  private ResultSetMetaData metaData;
  private int numberOfRows;
  private boolean connectedToDatabase = false;

  public ResultSetTableModel( String driver, String url,
    String query ) throws SQLException, ClassNotFoundException {
    Class.forName( driver );
    connection = DriverManager.getConnection( url );
    statement = connection.createStatement(
	ResultSet.TYPE_SCROLL_INSENSITIVE,
	ResultSet.CONCUR_READ_ONLY );
    connectedToDatabase = true;
    setQuery( query );
  }

  public Class getColumnClass( int column ) throws IllegalStateException {
    if ( !connectedToDatabase )
      throw new IllegalStateException( "Not Connected to Database" );

    try {
      String className = metaData.getColumnClassName( column + 1 );
      return Class.forName( className );
    }
    catch( Exception e) {
      e.printStackTrace();
    }
    return Object.class;

  } // end method getColumnClass

  public int getColumnCount() throws IllegalStateException {
    if ( !connectedToDatabase )
      throw new IllegalStateException( "Not Connected to Database" );

    try {
	return metaData.getColumnCount();
    }
    catch( SQLException e) {
      e.printStackTrace();
    }
    return 0;
  } // end method getColumnCount

  public String getColumnName( int column ) throws IllegalStateException {
    if ( !connectedToDatabase )
      throw new IllegalStateException( "Not Connected to Database" );

    try {
	return metaData.getColumnName( column + 1 );
    }
    catch( SQLException e) {
      e.printStackTrace();
    }
    return "";
  } // end method getColumnCount

  public int getRowCount() throws IllegalStateException {
  if ( !connectedToDatabase )
    throw new IllegalStateException( "Not Connected to Database" );

  return numberOfRows;
  } // end method getColumnCount


  public Object getValueAt( int row, int column )
      throws IllegalStateException {
    if ( !connectedToDatabase )
      throw new IllegalStateException( "Not Connected to Database" );

    try {
      resultSet.absolute( row + 1 );
      return resultSet.getObject( column + 1 );
    }
    catch( SQLException e) {
      e.printStackTrace();
    }

    return "";

  } // end method getColumnCount

  public void setQuery( String query )
      throws SQLException, IllegalStateException {
    if ( !connectedToDatabase )
      throw new IllegalStateException( "Not Connected to Database" );

    resultSet = statement.executeQuery( query );

    metaData = resultSet.getMetaData();

    resultSet.last();
    numberOfRows = resultSet.getRow();

    fireTableStructureChanged();

  }

  public void disconnectFromDatabase() {
    try {
      statement.close();
      connection.close();
    }
    catch( SQLException e ) {
      e.printStackTrace();
    }
    finally {
      connectedToDatabase = false;
    }
  }

} // end class ResultSetTableModel