Difference between revisions of "Java-Business-Application/C2/Java-servlets-and-JSPs/English-timed"

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Revision as of 22:37, 18 June 2015

Time Narration
00:01 Welcome to the spoken-tutorial on Java Servlets and JSPs.
00:06 In this tutorial, we will learn about:
00:09 Web server
00:10 Web container.
00:12 We will also learn to create a simple Java Servlet and JSP.
00:18 Here we are using:
00:20 * Ubuntu Version12.04
00:23 * Netbeans IDE 7.3
00:27 * JDK 1.7
00:29 * Firefox web-browser 21.0.
00:33 You can use any web-browser of your choice.
00:37 To follow this tutorial, you must have knowledge of:
00:41 * Core Java using Netbeans IDE and
00:45 * HTML.
00:47 If not, for relevant tutorials please visit our website.
00:52 Before moving onto Servlets and JSP, let us first understand a web server.
00:58 A web server is a system that delivers content to end-users over the Internet.
01:05 It is also known as Internet server.
01:10 A web container is a component of the web server that interacts with Java servlets.
01:18 It is also known as servlet container.
01:22 The servlet container allows the servlets to execute inside it.
01:28 Now, let us learn how to write a simple servlet.
01:32 Switch to the Netbeans IDE.
01:35 Click on the Project tab on the left hand side of the IDE.
01:40 Earlier we had created a simple Project named MyFirstProject.
01:46 You can see it here on the left hand side of the IDE.
01:50 Let us now create a simple servlet inside this Project.
01:55 So, right-click on MyFirstProject.
01:59 Go to New and click on Servlet.
02:03 A New Servlet window opens.
02:05 Type the Class Name as MyServlet.
02:09 Type the Package name as org.spokentutorial.
02:16 Then click on Next.
02:18 Click on Add information to deployment descriptor (web.xml).
02:23 We can see that the Class Name is org.spokentutorial.MyServlet.
02:30 We can see that Servlet Name is same as that of the Class Name which is MyServlet.
02:37 Note that the URL pattern is the same name as that of the Class Name. i.e MyServlet
02:45 We can change it to MyServletPath.
02:50 Then click on Finish.
02:53 The source code created by the IDE for MyServlet.java is seen in the Source Editor window.
03:01 We see MyServlet.java is created in the package org.spokentutorial.
03:09 Notice that a servlet is just like any other Java class
03:14 except that a servlet does not have a main method.
03:19 Now, let us learn something about Glassfish server.
03:24 A servlet is deployed in a servlet container.
03:28 We are using Glassfish as our server.
03:32 Servlet container is a component of Glassfish that interacts with servlets.
03:39 Now, let us come back to Netbeans IDE.
03:42 Note that MyServlet extends the HttpServlet.
03:48 At the bottom of the code, we can see HttpServlet methods.
03:54 Click on the plus sign on the left, to view these methods.
03:59 We see the methods - doGet, doPost and getServletInfo methods.
04:09 We can override these methods.
04:12 We can see that there is one more method named processRequest at the top.
04:18 We will delete processRequest and getServletInfo methods to avoid confusion.
04:25 So, we are left with two methods doGet and doPost.
04:31 For now, we will look at the doGet method.
04:35 doGetis the default method for any simple URLrequest.
04:41 So we will type some code inside the doGet method.
04:45 We had already deleted processRequest method.
04:49 So, remove the method call for processRequest method.
04:54 Also remove it from the doPost method.
04:58 Now, let us come to the doGet method
05:01 We can see that there are two parameters that are passed to the doGet method.
05:07 One is the request and the other is the response object.
05:12 Also notice that request is of type HttpServletRequest.
05:18 And response object is of type HttpServletResponse.
05:22 We will use the response object to send the HTML response back to the client side.
05:30 For that, we will have to create a PrintWriter object.
05:35 Notice that the PrintWriter class is already imported.
05:40 So, inside the doGet method type: PrintWriter space writer equal to responsedot getWriter open and close brackets semicolon
05:57 Press Enter.
05:59 On the next line type:
06:02 writer dot println within brackets and double quotes Welcome.
06:09 Then, press Ctrl S to save the file.
06:14 Now, let us run the servlet.
06:17 So, on the left hand side, in the Projects tab right click on MyServlet' dot java.
06:24 Then, click on Run File.
06:27 We get a Set Servlet Execution URI dialog box.
06:32 Click on OK.
06:35 When the browser window opens, look at the URL.
06:39 It is localhost colon 8080 slash MyFirstProject slash MyServletPath.
06:47 Here, MyFirstProject is the context name and MyServletPath is the URL pattern that we had set.
06:55 We see the text Welcome printed on the browser.
07:00 Now go back to the Netbeans IDE.
07:03 In the println method, we can pass html code.
07:07 For example, put Welcome in h3 tag.
07:12 Now, save the file.
07:14 Since we deployed this servlet earlier, we need not run it again.
07:20 The web container automatically detects it.
07:23 So, we can go back to the browser.
07:27 Refresh.
07:28 We see the message Welcome in a different format.
07:32 Now, come back to the IDE.
07:35 Thus, we have successfully created a servlet.
07:39 We can create any web application using servlets.
07:45 We used the servlet to display an HTML code.
07:49 Notice that we have HTML code inside the Java code.
07:54 Even though this is possible, it is difficult to do for large web applications.
08:00 And hence not a recommended practice.
08:03 It would be better to replace this using JSP (Java Server Pages.)
08:10 We will see the use of servlets and JSPs.
08:13 Servlets and JSPs are used together to separate presentation from content.
08:20 Servlets act as the controller and JSPs act as the view .
08:25 Servlets contain HTML code inside Java code.
08:30 JSPs contain Java code inside HTML code.
08:35 We will learn more about these in the coming tutorials.
08:39 Now, switch back to Netbeans IDE.
08:42 We will now create a simple JSP page.
08:47 So, right click on MyFirstProject.
08:50 Go to New
08:51 and click on JSP.
08:54 A new JSP window opens.
08:57 Type the Filename as welcome .
09:01 And then click on Finish.
09:04 Click on the Projects tab . On the left hand side,
09:07 We can see that Welcome.jsp is under Web Pages folder.
09:13 Now, in the editor, change Hello World to Welcome.
09:19 Notice that Welcome is within h1 tags.
09:23 Now, save the file.
09:25 Come back to the browser.
09:27 In the url, after MyFirstProject slash, type welcome.jsp.
09:35 We see the output Welcome.
09:38 Therefore, for presentation purpose JSP is preferred.
09:42 Let us summarize.
09:44 In this tutorial, we have learnt:
09:47 * About web server and web container
09:49 * To create a simple servlet
09:52 * To create a simple JSP.
09:55 Please make sure that you have completed this tutorial before proceeding further.
10:01 Watch the video available at the following link.
10:04 It summarizes the Spoken Tutorial project.
10:08 If you do not have good bandwidth, you can download and watch it.
10:13 The Spoken Tutorial Project Team:
10:15 Conducts workshops using spoken tutorials
10:19 Gives certificates for those who pass an online test.
10:22 For more details, please write to: contact at spoken hyphen tutorial dot org.
10:28 Spoken Tutorial Project is a part of the "Talk to a Teacher project".
10:32 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10:40 More information on this mission is available at http://spoken-tutorial.org/NMEICT- Intro
10:50 The Library Management System has been contributed by a leading software MNC, through their Corporate Social Responsibility program.
11:00 They have also validated the content for this spoken tutorial.
11:04 This is Arya Ratish from IIT Bombay, signing off.

Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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