Java-Business-Application/C2/Java-servlets-and-JSPs/English-timed
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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 methodtype PrintWriter space writerequal to response dot 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 slashtype 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. |