/* Example for setup and environment variables (database pool): ### Vorbereitungen auf dbpraktikum: ### Setup for Java: (am besten in .bash_profile eintragen) export PATH=/usr/local/java/bin:$PATH ### CLASSPATH setting: ### For the connection to the Oracle JDBC database the following ### classes are needed: ### $ORACLE_HOME/jdbc/lib/classes12.zip for java 1.2+ ### in the following circumstances: ### * At compile time, if the method ### DriverManager.registerDriver is used directly without ### method Class.forName. ### * The program/applet is not run as .jar/.zip file that contains ### also the above classes. ### (am besten in .bash_profile eintragen) export CLASSPATH=.:$ORACLE_HOME/jdbc/lib/classes12.zip */ /* Example for compiling and running: ### Compiling: javac .java ### Running as application: java ### Running as applet by appletviewer: ### Now it will be a little more complicated :-) ### The appletviewer does not evaluate the setting of the ### environment variable CLASSPATH, when it runs Java on ### the applet. There are two methods to deal with this ### situation. ### ### a) The official one, see "Packaging Applets": ### http://www.dbis.informatik.uni-goettingen.de/ ### Teaching/DBP/orajdbc/advanc.htm#1003944 ### Example, your class is called frame and frame.class ### is in current directory: unzip $ORACLE_HOME/jdbc/lib/classes12 -d emptydir cp frame.class emptydir/ cd emptydir jar cf ../frame.jar * cd .. ### Then, the file frame.html has to be changed: ### The jar file is added in the APPLET tag of the HTML page: ### Next, read the section "Security issues" ### b) Quick and dirty: The CLASSPATH can be given as option ### in the call of appletviewer: ### Do not forget to read and include the "Security Issues" below! appletviewer -J-classpath -J$ORACLE_HOME/jdbc/lib/classes12.zip frame.html ### Security issues ### Because of applet security restrictions, an applet cannot ### connect to a server other than the host where the web server ### is running. The JDBC documentation describes two methods, ### running the Oracle8 Connection Manager on the web server ### or using signed applets. ### See: http://www.dbis.informatik.uni-goettingen.de/ ### Teaching/DBP/orajdbc/advanc.htm#1003752 ### ### Other method: Customized policy file ### Create a policy file "mypolicy": grant { permission java.net.SocketPermission "134.76.81.14:1521", "connect, resolve"; }; ### Finally, the appletviewer can be called ### telling it to use the policy file: appletviewer \ -J-Djava.security.manager \ -J-Djava.security.policy=mypolicy \ frame.html ### (The backslash tells the shell to continue the line on the ### next one, alternatively all can be written in one line ### without the backslashes.) */ // Import the java classes used in applets import java.awt.*; import java.awt.event.*; /* You are not restricted to the AWT classes, also Swing may be used. */ // Import the JDBC classes import java.sql.*; public class frame extends Frame implements ActionListener { public static void main (String[] args) { new frame(); } // The connection to the database private Connection conn = null; // Input area private TextField input = new TextField(60); // The button to push for executing the query private Button submitQuery = new Button("submitQuery"); // The place where to dump the query result private TextArea output = new TextArea(); // For managing the layout private GridBagConstraints gbc = new GridBagConstraints(); public frame () { super("Rahmen zu JDBC"); try { // Syntax for ORACLE driver: // "jdbc:oracle:thin:/@ // ::" // The JDBC driver to load // a) DriverManager.registerDriver can be called directly: // DriverManager.registerDriver( // new oracle.jdbc.driver.OracleDriver()); // or // b) Class.forName can be used, then // * class oracle.jdbc.driver.OracleDriver has not to // known at compile time, // * DriverManager.registerDriver is called automatically, // * but ClassNotFoundException has to be catched. Class.forName("oracle.jdbc.driver.OracleDriver"); // connect string // Replace "jdbc_x/jdbc_x" by your group account. // Example for group 8: "jdbc_8/jdbc_8" String account = "jdbc_x/jdbc_x"; // Server: s4.ifi.informatik.uni-goettingen.de String server = "s4.ifi.informatik.uni-goettingen.de:1521"; // If you are behind a firewall that blocks this port, // you can use a tunneling application (stunnel, ...) // or use local forwarding by ssh. // Example for user "foo" that logins into "dbpraktikum": // ssh -L 1521:134.76.81.14:1521 foo@dbpraktikum.ifi.informatik.uni-goettingen.de // Then the server string contains the port on the // local machine: // String server = "127.0.0.1:1521"; String url = "jdbc:oracle:thin:" + account + "@" + server + ":dbis"; conn = DriverManager.getConnection(url); } catch (ClassNotFoundException e) { System.out.println("!!! Error: Class '" + e.getMessage() + "' not found!"); System.exit(1); } catch (SQLException e) { System.out.println("!!! Error: Connection failed:"); System.out.println(e.getMessage()); System.exit(1); } // Layout setLayout(new GridBagLayout()); input.addActionListener(this); submitQuery.addActionListener(this); // add components gbc.gridx = 0; gbc.gridy = 0; add(input, gbc); gbc.gridy = 1; add(output, gbc); gbc.gridx = 1; gbc.gridy = 0; add(submitQuery, gbc); addWindowListener(new WindowAdapter() { public void windowClosing (WindowEvent e) { System.exit(0); } }); pack(); setVisible(true); } public void actionPerformed (ActionEvent e) { Object origin = e.getSource(); // The compiler generates an error, if a method is used // that throws a SQLException, e.g. dispResult()! try { Statement stmt = conn.createStatement (); if ( origin == submitQuery ) { String query = input.getText(); // execute the query ... // ... and print the result with the help of dispResult // Execute the query output.append ("Executing query " + query + "\n\n"); ResultSet rset = stmt.executeQuery (query); // Write the result set dispResult(rset); rset.close(); return; } // Treatment of the remaining exercises // (for instance, one button per exercise) // if ( origin == execJob ) { // execute exercise X ... // ... and print the result by displayResult // here the method is called that has to be written // doJob(); // return; // } } catch (SQLException exc) { output.setText("Error while executing the command:\n" + exc.getMessage()); } } // ****************************************************** // * dispResult * // * Display all the columns and rows of the result set * // ****************************************************** private void dispResult (ResultSet rs) throws SQLException { // This method must be implemented. } }