Selected Sections of Applied Informatics Lab 3

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Arron Chase
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1 Selected Sections of Applied Informatics Lab 3 Use the results of the servlet in Swing application. 1. Setting up a server for resolving the square equation 1. Create new NetBeans project by selecting from menu File an optionnew Project ; select on the panel Categories: Java, in panel Project: Java Class Library. And press [Next]. 2. Give the design the name SquareEquation. By button [Browse ] select Z:\as a location of the project and press Finish. The folders of the empty project (without classes) will be created. 3. Add to the project the source file Servlet named EquationServlet. Import library servletapi.jar. Check if the project complements itself. 4. In the method processrequest delete of the try content (all instructions out.println)and add if necessary a section catch (Exception e) {. Bring the out variable declaration through curly brackets. Please note in the catch-up section in the error instruction manual After modification the code should look like this: PrintWriter out = response.getwriter(); try{ /* programme code will be here */ catch(exception e) { out.println(e.getmessage()); 5. In instructionresponse.setcontenttype( )change the format of the server response from HTML to plain text by converting it into plain text. text/html for text/plain 6. Beforetryblockenter the variables a, b and ctypucałkowitego. They will keep the values of the relevant parameters transmitted from the form int a=0, b=0, c=0; 7. At the begining of thetryinstruction add a reading instruction for parameter "a" to the text variable parama. Then convert the text value to total type using instructions Integer.parseInt strona 1

2 String parama = request.getparameter("a"); a = Integer.parseInt( parama ); 8. Assign variable b and c values of the corresponding parameters in a similar way (from this place and to the end all instructions are placed one after the other). 9. Check the value of parameter a. If it is zero, interrupt the calculation with a corresponding message. if (a == 0) throw new Exception("This is not a square equation.!"); 10. Calculate the value of the auxiliary variable delta int delta = b * b - 4 * a * c; 11. If the delta variable is negative, the square equation does not have actual elements. Interrupt the calculation by generating a correspondingmessage. if (delta < 0) throw new Exception("Lack of real elements"); 12. Determine how many elements the square equation has. If the value of the delta variable is zero, the equation has only one element if (delta == 0) { double x0 = -b / (2 * a); out.println("x0 = " + x0); 13. In other cases, the equation has two elements. Calculate them and send them to the output stream represented by the variable out if( delta > 0 ){ double x1 = (-b - Math.sqrt(delta)) / (2 * a); double x2 = (-b + Math.sqrt(delta)) / (2 * a); out.println("x1=" + x1 + "x2=" + x2); 14. Compile the class EquationServlet. Put the file EquationServlet.class in directory WEB- INF/classes. Modify the file accordingly web.xml by registering the servlet at the /EquationServlet network address. Restart the Apache server and check if there are any configuration errors. 15. Start your web browser. Check that the serviettes solve the square equation x^2-4x=0 by typing in the address bar. strona 2

3 2. Construction of HTML page for entering square equation parameters 1. In the window Projects right-click on the project name SquareEquation and by New select file typehtml File (can be use also menu File New File.) 2. Change file name from newhtml to EquationForm and press Finish. The HTML file frame appears in the editor window. 3. In the HTML file, change the window header <title>.</title> for Square equation 4. Remove all contents inside the tags <body> </body> 5. At the beginning of <body> place the inscription. Square equationax<sup>2</sup> + BX + C = 0 Use <h2 >... </h2 > tags to change the font. Identify the names of parameters a, b and c in bold type and the entire formula in italics <i>. Square equationax 2 + BX + C = 0 6. Add an HTML form to the text of your HTML document <form method="get" action="/equationservlet"> </form> The GET method sends the data to the URL specified by the "action" parameter. 7. In the next part of the <form> form, put a description of parameter a and textbox for entering the appropriate value. <p> A = <input type="text" name="a"/> 8. Define a selection list for the variable value B <p> B = <select name="b"> </select> <option value="0">0</option> 9.Complete the selection list with -9, -6, -6, -4, -2, -2,1,2,5,5,7 by adding additional <option> elements with corresponding values. 10. Define a group of radio type buttons, with which you can select a value for parameter C strona 3

<p> C = <input type="radio" name="c" value="-10">-10 11.

4 <p> C = <input type="radio" name="c" value="-10"> Add the next radio button by changing the value of the attribute value, for the values: - 10, -7, -4, -1, -1,0,1,2,2,4,5,5,9, adding them below. 12. Place the submit button in the next part of the form, using which the data of the form will be sent to the web server indicated in the action field of the <form> tag. <input type="submit"> 13. place the EquationForm.html file in the web server ROOT directory 14. Start the web server (if it has not been started before). 15. Start your web browser. Enter URL address Enter any data into the form fields and send your request to the server. Make sure that the application works and correctly solves square equations for all cases (no real elements, one element, two elements, a=0). strona 4

3. Swing application that connects to the servlet and reads the answer 1. Create innetbeans new Java Class Library project. Name it EquationForm 2. Add class JFrame from category Swing GUI Forms. 3.

5 3. Swing application that connects to the servlet and reads the answer 1. Create innetbeans new Java Class Library project. Name it EquationForm 2. Add class JFrame from category Swing GUI Forms. 3. Include type elements in the main application window Label (4 pcs.), TextField (3 pcs.), TextArea and button JButton. Change the inscriptions on the elements according to the drawing. 4. Use the pop-up menu to name text fields: texta, textb, textc, wynik 5. Double-click the button [Rozwiązanie] generate the event handling method ActionPerformed strona 5 private void jbutton1actionperformed( java.awt.event.actioneventevt ) { 6. Place in the method jbutton1actionperformedstructure for capturing errors try { /* further instructions will be added here */ catch (IOExceptionioe) { wynik.settext(ioe.tostring()); 7. Create a URL that stores information about the web address at which the servlet operates EquationServlet

6 URL url = new URL("http", "localhost", 8084, "/EquationServlet"); Open the data transfer connection URLConnectionurlConn = url.openconnection(); urlconn.setdooutput(true); 8. Create output data stream (servlet data transfer) ByteArrayOutputStreambyteStream = new ByteArrayOutputStream(512); PrintWriter out = new PrintWriter(byteStream, true); 9. Read the user input data into TextField elements and save them to the output stream. String dane = "&a=" + texta.gettext() + "&b=" + textb.gettext() + "&c=" + textc.gettext(); out.print(dane); 10. Insert the data stream cleaning instruction. out.flush(); 11. Set the query properties (data size and type of application) urlconn.setrequestproperty("content-length", String.valueOf(byteStream.size())); urlconn.setrequestproperty("content-type", "application/x-www-form-urlencoded"); 12. Send a query to the servlet using the following instructions bytestream.writeto( urlconn.getoutputstream() ); 13. Create an object with which the servlet response will be loaded BufferedReader in = new BufferedReader( new InputStreamReader(urlConn.getInputStream())); 14. Read the server response strona 6

7 String result = in.readline(); 15. Display the server response in the "wynik" text field. wynik.settext(result); 16. Compile the application. Eliminate any compilation errors. 17. Check that Apache server and application are running EquationServletand is correctly configured 18. Rum application EquationForm. Enter the parameters and check if after clicking[rozwiązanie] the data is transferred to the server and the answer is displayed in the Wynik text box. The task of self-solving: Modify Swing to display the X1 and X2 values in separate text fields - so that they can be used for further calculations. Hint: Use the String class Split method to separate X1 a X2 and then Double. parsedouble to read the value generated by the servlet. strona 7

Forms, CGI. Objectives

Forms, CGI. Objectives Forms, CGI Objectives The basics of HTML forms How form content is submitted GET, POST Elements that you can have in forms Responding to forms Common Gateway Interface (CGI) Later: Servlets Generation