Applet - Servlet - Database - Servlet- Applet

Question

Hi All,
I am using Oracle8i and IE 5.0. I am trying to retrieve the data from a db table and display it.
Sequence is as following:
1. Query passed to the applet.
2. Servlet excutes this query using JDBC and returns the resultset to applet.
3. Applet displaysthe results.
Is there anybody who has a code sample to do this, my id is [email protected] ? I am totally new to java and servlets. I would really appreciate any help.
Thanks a lot.
Manuriti
[email protected]

Answer 1

I've never dealt with the code to handle the applet portion of what you're trying to do, but I can help you with the servlet stuff.
Your servlet should contain code to accomplish the following steps:
1. Load an Oracle JDBC driver into memory.
2. Open a JDBC connection to the Oracle database.
3. Create a JDBC Statement object which contains the appropriate Oracle SQL code.
4. Execute the Statement object, which will return a ResultSet.
5. Read the ResultSet data.
6. Pool or close the Statement and Connection objects.
All of these steps are simple. Here's what they might look like in practice:
// load the Oracle driver
Class.forName("oracle.jdbc.driver.OracleDriver");
// open the connection
String cs = "jdbc:oracle:[email protected]:1521:DBNAME"; // connection string
String userName = "scott";
String password = "tiger";
Connection con = DriverManager.getConnection(cs, userName, password);
// create a Statement object
Statement stmt = con.createStatement();
// create a ResultSet object
ResultSet rs = stmt.executeQuery("select * from DUAL"); // your SQL here
// INSERT CODE HERE TO READ DATA FROM THE RESULTSET
// close the Statement object
stmt.close();
// close the Connection object
con.close();
So that's how you get data from your Oracle database. Now, how do you pass it to your applet? Well, this is hardly trivial. Typically, servlets return an HTML-formatted text stream. It is possible to have an applet communicate with a servlet, but that raises security issues that I don't fully understand. I believe you would have to have your user's browsers set to the lowest possible security settings, otherwise the browser won't let the applet open a socket to a foreign IP, but again, I'm shaky on that one.
Anywho, let me know if this was of help and if you have more questions on the servlet/applet stuff. I can probably help you with more specific questions,.