jdbcadapter.java

这是一个用Jtable的一个学习的例子,内容比较简单,但很实用!

/*
 * @(#)JDBCAdapter.java	1.16 04/07/26
 *
 * Copyright (c) 2004 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

/*
 * @(#)JDBCAdapter.java	1.16 04/07/26
 */

/**
 * An adaptor, transforming the JDBC interface to the TableModel interface.
 *
 * @version 1.20 09/25/97
 * @author Philip Milne
 */

import java.util.Vector;
import java.sql.*;
import javax.swing.table.AbstractTableModel;
import javax.swing.event.TableModelEvent;

public class JDBCAdapter
    extends AbstractTableModel {
  Connection connection;
  Statement statement;
  ResultSet resultSet;
  String[] columnNames = {};
  Vector rows = new Vector();
  ResultSetMetaData metaData;

  public JDBCAdapter(String url, String driverName,
                     String user, String passwd) {
    try {
      Class.forName(driverName);
      System.out.println("Opening db connection");

      connection = DriverManager.getConnection(url, user, passwd);
      statement = connection.createStatement();
    }
    catch (ClassNotFoundException ex) {
      System.err.println("Cannot find the database driver classes.");
      System.err.println(ex);
    }
    catch (SQLException ex) {
      System.err.println("Cannot connect to this database.");
      System.err.println(ex);
    }
  }

  public void executeQuery(String query) {
    if (connection == null || statement == null) {
      System.err.println("There is no database to execute the query.");
      return;
    }
    try {
      resultSet = statement.executeQuery(query);
      metaData = resultSet.getMetaData();

      int numberOfColumns = metaData.getColumnCount();
      columnNames = new String[numberOfColumns];
      // Get the column names and cache them.
      // Then we can close the connection.
      for (int column = 0; column < numberOfColumns; column++) {
        columnNames[column] = metaData.getColumnLabel(column + 1);
      }

      // Get all rows.
      rows = new Vector();
      while (resultSet.next()) {
        Vector newRow = new Vector();
        for (int i = 1; i <= getColumnCount(); i++) {
          newRow.addElement(resultSet.getObject(i));
        }
        rows.addElement(newRow);
      }
      //  close(); Need to copy the metaData, bug in jdbc:odbc driver.
      fireTableChanged(null); // Tell the listeners a new table has arrived.
    }
    catch (SQLException ex) {
      System.err.println(ex);
    }
  }

  public void close() throws SQLException {
    System.out.println("Closing db connection");
    resultSet.close();
    statement.close();
    connection.close();
  }

  protected void finalize() throws Throwable {
    System.out.println("finalize called");
    close();
    super.finalize();
  }

  //////////////////////////////////////////////////////////////////////////
  //
  //             Implementation of the TableModel Interface
  //
  //////////////////////////////////////////////////////////////////////////

  // MetaData

  public String getColumnName(int column) {
    if (columnNames[column] != null) {
      return columnNames[column];
    }
    else {
      return "";
    }
  }

  public Class getColumnClass(int column) {
    int type;
    try {
      type = metaData.getColumnType(column + 1);
    }
    catch (SQLException e) {
      return super.getColumnClass(column);
    }

    switch (type) {
      case Types.CHAR:
      case Types.VARCHAR:
      case Types.LONGVARCHAR:
        return String.class;

      case Types.BIT:
        return Boolean.class;

      case Types.TINYINT:
      case Types.SMALLINT:
      case Types.INTEGER:
        return Integer.class;

      case Types.BIGINT:
        return Long.class;

      case Types.FLOAT:
      case Types.DOUBLE:
        return Double.class;

      case Types.DATE:
        return java.sql.Date.class;

      default:
        return Object.class;
    }
  }

  public boolean isCellEditable(int row, int column) {
    try {
      return metaData.isWritable(column + 1);
    }
    catch (SQLException e) {
      return false;
    }
  }

  public int getColumnCount() {
    return columnNames.length;
  }

  // Data methods

  public int getRowCount() {
    return rows.size();
  }

  public Object getValueAt(int aRow, int aColumn) {
    Vector row = (Vector) rows.elementAt(aRow);
    return row.elementAt(aColumn);
  }

  public String dbRepresentation(int column, Object value) {
    int type;

    if (value == null) {
      return "null";
    }

    try {
      type = metaData.getColumnType(column + 1);
    }
    catch (SQLException e) {
      return value.toString();
    }

    switch (type) {
      case Types.INTEGER:
      case Types.DOUBLE:
      case Types.FLOAT:
        return value.toString();
      case Types.BIT:
        return ( (Boolean) value).booleanValue() ? "1" : "0";
      case Types.DATE:
        return value.toString(); // This will need some conversion.
      default:
        return "\"" + value.toString() + "\"";
    }

  }

  public void setValueAt(Object value, int row, int column) {
    try {
      String tableName = metaData.getTableName(column + 1);
      // Some of the drivers seem buggy, tableName should not be null.
      if (tableName == null) {
        System.out.println("Table name returned null.");
      }
      String columnName = getColumnName(column);
      String query =
          "update " + tableName +
          " set " + columnName + " = " + dbRepresentation(column, value) +
          " where ";
      // We don't have a model of the schema so we don't know the
      // primary keys or which columns to lock on. To demonstrate
      // that editing is possible, we'll just lock on everything.
      for (int col = 0; col < getColumnCount(); col++) {
        String colName = getColumnName(col);
        if (colName.equals("")) {
          continue;
        }
        if (col != 0) {
          query = query + " and ";
        }
        query = query + colName + " = " +
            dbRepresentation(col, getValueAt(row, col));
      }
      System.out.println(query);
      System.out.println("Not sending update to database");
      // statement.executeQuery(query);
    }
    catch (SQLException e) {
      //     e.printStackTrace();
      System.err.println("Update failed");
    }
    Vector dataRow = (Vector) rows.elementAt(row);
    dataRow.setElementAt(value, column);

  }
}