essentialjdbc.java

Java Classic Examples是我买的两本书：《JAVA经典实例》和《java入门经典源代码》里边附送光盘里带的源码

import java.sql.*;

public class EssentialJDBC
{

  public static void main (String[] args)
  {
    EssentialJDBC SQLExample = new EssentialJDBC();    // Create application object

    SQLExample.getResultsByColumnName();
    SQLExample.getResultsByColumnPosition();
    SQLExample.getAllColumns();
    SQLExample.closeConnection();
  }

  public EssentialJDBC()
  {
    try
    {
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
      connection = DriverManager.getConnection(sourceURL);
      statement = connection.createStatement();
    }
    catch(SQLException sqle)
    {
      System.err.println("Error creating connection");
    }
    catch(ClassNotFoundException cnfe)
    {
      System.err.println(cnfe.toString());
    }
  }


  void getResultsByColumnPosition()
  {
    try
    {
      ResultSet authorResults = statement.executeQuery(queryIDAndName);

      int row = 0;
      while (authorResults.next())
      {
        System.out.print("\nRow " + (++row) + ") ");
        for(int i = 1 ; i<=3 ; i++)
          System.out.print((i>1?", ":" ")+authorResults.getString(i));
      }

      authorResults.close();                            // Close the result set
    }
    catch (SQLException ex)
    {
      System.err.println("\nSQLException-------------------\n");
      System.err.println("SQLState: " + ex.getSQLState());
      System.err.println("Message : " + ex.getMessage());
    }

  }

  void getResultsByColumnName()
  {
    try
    {
      ResultSet authorResults = statement.executeQuery(queryWildcard);
      int row = 0;

      while(authorResults.next())
        System.out.println("Row " + (++row) + ") "+
                           authorResults.getString("authid")+ " " + 
                           authorResults.getString("lastname")+ " , "+
                           authorResults.getString("firstname"));

      authorResults.close();
    }
    catch (SQLException sqle)
    {
      System.err.println ("\nSQLException-------------------\n");
      System.err.println ("SQLState: " + sqle.getSQLState());
      System.err.println ("Message : " + sqle.getMessage());
    }

  }

  void getAllColumns()
  {
    try
    {
      ResultSet authorResults = statement.executeQuery(queryWildcard);

      ResultSetMetaData metadata = authorResults.getMetaData();
      int columns = metadata.getColumnCount();          // Column count
      int row = 0;
      while (authorResults.next())
      {
        System.out.print("\nRow " + (++row) + ") ");
        for(int i = 1 ; i<=columns ; i++)
          System.out.print((i>1?", ":" ")+authorResults.getString(i));
      }

      authorResults.close();                            // Close the result set
    }
    catch (SQLException ex)
    {
      System.err.println("\nSQLException-------------------\n");
      System.err.println("SQLState: " + ex.getSQLState());
      System.err.println("Message : " + ex.getMessage());
    }

  }

  // Close the connection
  void closeConnection()
  {
    if(connection != null)
    try
    {
      connection.close();
      connection = null;
    }
    catch (SQLException ex)
    {
      System.out.println("\nSQLException-------------------\n");
      System.out.println("SQLState: " + ex.getSQLState());
      System.out.println("Message : " + ex.getMessage());
    }
  }

  Connection connection;
  Statement statement;
  String sourceURL = "jdbc:odbc:technical_library";
  String queryIDAndName = "SELECT authid, lastname, firstname FROM authors";
  String queryWildcard = "SELECT * FROM authors";          // Select all columns
}