jdbcapplet.java

一个applet与oracle进行连接的例子(大家知道applet与数据库是比较难通讯的

/*
 * This sample applet just selects * from the database
 */

// Import the JDBC classes
import java.sql.*;

// Import the java classes used in applets
import java.awt.*;
import java.io.*;
import java.util.*;

public class JdbcApplet extends java.applet.Applet
{
  // The driver to load
  static final String driver_class = "oracle.jdbc.driver.OracleDriver";

  // The connect string: naturally not the real one 
  static final String connect_string =
                  "jdbc:oracle:thin:user/[e-mail]:1521:orcl";
 
  // The query we will execute
  static final String query = "select 'Hello JDBC: ' || sysdate from dual";
  

  // The button to push for executing the query
  Button execute_button;

  // The place where to dump the query result
  TextArea output;

  // The connection to the database
  Connection conn;

  // Create the User Interface
  public void init ()
  {
    this.setLayout (new BorderLayout ());
    Panel p = new Panel ();
    p.setLayout (new FlowLayout (FlowLayout.LEFT));
    execute_button = new Button ("Execute");
    p.add (execute_button);
    this.add ("North", p);
    output = new TextArea (10, 60);
    this.add ("Center", output);
  }

  // Do the work
  public boolean action (Event ev, Object arg)
  {
    if (ev.target == execute_button)
    {
      try
      {
	// Clear the output area
	output.setText ("");
	// See if we need to open the connection to the database
	if (conn == null)
	{
	  // Load the JDBC driver
	  output.appendText ("Loading JDBC driver " + driver_class + "\n");
	  Class.forName (driver_class);

	  // Connect to the databse
	  output.appendText ("Connecting to " + connect_string + "\n");
          netscape.security.PrivilegeManager.enablePrivilege("UniversalConnect");
	  conn = DriverManager.getConnection (connect_string);
	  output.appendText ("Connected\n");
	}

	// Create a statement
	Statement stmt = conn.createStatement ();

	// Execute the query
	ResultSet rset = stmt.executeQuery (query);

	// Dump the result
	while (rset.next ())
	  output.appendText (rset.getString (1) + "\n");

        output.appendText ("And now emps: \n");
        // Create a Statement
        stmt = conn.createStatement ();

        // Select * from emp 
        rset = stmt.executeQuery ("select * from emp");

        // Iterate through the result and print all rows 
        while (rset.next ()) {
           output.appendText(rset.getString (1) + ", " + rset.getString (2) +  ", " + rset.getString (3) + ", " + rset.getString (4) + ", " + rset.getString (5));
           output.appendText("\n");
        }
      }
      catch (Exception e)
      {
	// Oops
	output.appendText (e.getMessage () + "\n");
      }
      return true;
    }
    else
      return false;
  }
}