Calling a Servlet from an Applet

[Anonymous]

How can I pass things (parameters,strings,...) from an applet to a Servlet?.
I'm connected from the Applet to the Servlet with its URL.I get URL's OutputStream and send a string.
In the Servlet I'm trying to read the sended string with the ReadLine() method but the servlet don't run good. It waits for something to read that never arrives.
Thanks.

[Thomas Paul]

Here is an example of an applet calling a servlet by passing it an object and then getting an object back from the servlet. The rule is the objects passed back and forth must be serializable. So you could pass a String containing a SQL statement from the applet to the servlet and get back a Vector (not a ResultSet which isn't serializable) from the servlet.
This example is very simple. All the applet does is pass an object to the servlet which adds 10 to an int inside the object and then passes the object back again.
Here is the class passed back and forth:

import java.io.*;
public class TestData implements Serializable {
    public int value = 0;
}

Here is the applet.

    void button1_ActionPerformed(ActionEvent event)
    {
        try {
        TestData testData = new TestData();
        testData.value = Integer.parseInt(textField1.getText());
            URL servlet = new URL("http://www.mydomain.com/servlet/GetObjectServlet");
            URLConnection myConn = servlet.openConnection();
            myConn.setRequestProperty("CONTENT_TYPE", "application/octet-stream");
            myConn.setDoOutput(true);
            ObjectOutputStream os = new ObjectOutputStream(myConn.getOutputStream());
            os.writeObject(testData);
            os.flush();
            ObjectInputStream is = new ObjectInputStream(myConn.getInputStream());
            testData = (TestData)is.readObject();
            is.close();
            os.close();
            label3.setText(String.valueOf(testData.value));
        } catch (Exception e) {
            System.out.println("exception: " + e.getMessage());
            e.printStackTrace(System.out);
        }
    }

Here is the servlet:

    public void service(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
    {
        //get Input and Output Streams
        ObjectInputStream ois = new ObjectInputStream(req.getInputStream());
        ObjectOutputStream oos = new ObjectOutputStream(resp.getOutputStream());
        //set content type for writing the output
        resp.setContentType("application/octet-stream");
        try {
            TestData testData = (TestData)(ois.readObject());
            System.out.println("Got TestData:" + testData.value);
            testData.value = testData.value + 10;
            oos.writeObject(testData);
            System.out.println("Sending TestData:" + testData.value);
            oos.close();
        } catch (Exception e) {
            System.out.println("Crash:" + e.getMessage());
        }
        return;
    }

[This message has been edited by Thomas Paul (edited February 28, 2001).]