Difference between revisions of "Java-Business-Application/C2/Servlet-Methods/English-timed"
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Revision as of 22:27, 29 June 2015
| Time | Narration |
| 00:01 | Welcome to the spoken-tutorial on Servlet Methods. |
| 00:06 | In this tutorial, we will learn to: |
| 00:08 | * create a simple login form using JSP |
| 00:13 | * Pass parameters using doGet method |
| 00:16 | * Pass parameters using doPost method |
| 00:20 | * Difference between doGet and doPost methods. |
| 00:25 | Here we are using: |
| 00:26 | Ubuntu Version 12.04 |
| 00:30 | Netbeans IDE 7.3 |
| 00:33 | JDK 1.7 |
| 00:36 | Firefox web-browser 21.0. |
| 00:39 | You can use any web-browser of your choice. |
| 00:43 | To follow this tutorial, you must know: |
| 00:46 | * Core Java using Netbeans IDE |
| 00:49 | * HTML |
| 00:51 | * Basics of Java Servlets and JSPs. |
| 00:56 | If not, for relevant tutorials, please visit our website. |
| 01:00 | We will begin by creating our web application- the Library Management System. |
| 01:06 | First, we will create the Home page. |
| 01:09 | The Home page will contain a simple login form. |
| 01:14 | It will allow authenticated users to login to the Library Management System. |
| 01:20 | Now, let us switch to Netbeans IDE. |
| 01:23 | Let us go to the index dot jsp page that we had already modified earlier. |
| 01:30 | I have modified this page to create our home page. |
| 01:35 | We keep the title as Home Page. |
| 01:38 | Inside the body, we have a table with border equal to 1. |
| 01:44 | You can have a look at the code here. |
| 01:47 | Inside the table, we have included a heading Welcome to Library Management System. |
| 01:54 | Next, we have paragraph tag that includes This is the home page for Library Management System. |
| 02:03 | Then we have a hyperlink which links to a page called visitorHomePage dot jsp. |
| 02:11 | We will create this page later. |
| 02:13 | Next, we have a very simple login form. |
| 02:18 | This form allows a registered user to login . |
| 02:22 | Before creating the form , you will have to create a servlet named GreetingServlet. |
| 02:28 | So pause the tutorial here and create a new servlet as explained in the earlier tutorial. |
| 02:35 | Note that the servlet name is GreetingServletand |
| 02:39 | the URL pattern should be GreetingServletPath. |
| 02:44 | This form has two input elements - Username and Password. |
| 02:50 | It also has a Submit button that says Sign In. |
| 02:55 | Next, we have a paragraph tag that includes a link to addUser.jsp. |
| 03:03 | This is the registration page for those users who have not yet registered. |
| 03:09 | Now, let us go to our GreetingServlet.java. |
| 03:14 | Note that GreetingServlet.java is created in the same package org.spokentutorial. |
| 03:23 | Now, this servlet will be able to access the form data from the request object. |
| 03:30 | This servlet will act as a controller. |
| 03:33 | Do you recall that we had come across controller earlier? |
| 03:38 | Now, we will see what the servlet does as a controller. |
| 03:42 | The form data will reside in the request object. |
| 03:46 | The first task is to retrieve the form data parameters. |
| 03:51 | This is done using the getParameter method on the request object. |
| 03:57 | So, let us switch to Netbeans IDE. |
| 04:02 | Type inside the doGet method: |
| 04:04 | PrintWriter space out equal to response dot getWriter(). |
| 04:14 | Next, we will retrieve the form data parameters. |
| 04:18 | So that on the next line, type: |
| 04:20 | String space username equal to request dot getParameter within brackets and double quotes userName semicolon. |
| 04:35 | Note that this userName is the name we have included in the form tag for User Name. |
| 04:43 | Similarly, we will retrieve the password also. |
| 04:48 | So, on the next line, type: String space password equal to request dot getParameter within brackets and double quotes password semicolon. |
| 05:03 | Next, we will print the UserName in the output. |
| 05:08 | So, on the next line, type: |
| 05:10 | out dot println within brackets and double quotes Hello from GET Method plus username. |
| 05:21 | Now, to run this project, right-click on MyFirstProject. |
| 05:27 | Click on Clean and Build. |
| 05:29 | Again right click on MyFirstProject , click on Run. |
| 05:35 | So, the server is up and running. |
| 05:38 | It has deployed MyFirstProject. |
| 05:41 | We have got our Home page displayed in the browser. |
| 05:45 | Observe that the title of the page is Home Page. |
| 05:50 | We can see a very simple login form here. |
| 05:54 | Let me enter the Username and Password. |
| 05:58 | I will type arya as the Username. |
| 06:02 | And arya*123 as the Password. |
| 06.06 | Then click on Sign In. |
| 06:09 | We can see that we have got the output Hello from GET Method arya. |
| 06:15 | Now, the user was able to login here because we have not included any validation inside the code. |
| 06:24 | We will do this in the later tutorial. |
| 06:28 | Now, have a look at the URL here. |
| 06:31 | It is localhost colon 8080 slash MyFirstProject slash GreetingServletPath question mark userName equal to arya and password equal to arya *123. |
| 06:49 | Now, the form data is separated from the page information by a question mark. |
| 06:56 | We can see that the username and password that we had entered in the form are inside the URL also. |
| 07:05 | Now let us try to do the same, using POST Method. |
| 07:10 | So, switch back to the IDE. |
| 07:12 | Copy the code we had written for doGet Method and paste in the doPost Method. |
| 07:20 | Now, change the println statement to Hello from POST Method. |
| 07:27 | Now, let us open index dot jsp. |
| 07:31 | Here, we must change the method attribute of the form tag to POST. |
| 07:37 | You can have a look at this code now. |
| 07:42 | We have form action equal to GreetingServletPath method equal to POST. |
| 07:49 | Now, we will run this Project again. |
| 07:53 | So, right click on MyFirstProject and click on Run. |
| 07:58 | We have got the output similar to the one we got when we used the GET method. |
| 08:04 | So, let us type UserName and Password again. |
| 08:08 | Then click on Sign In. |
| 08:12 | Note that we have got Hello from POST Method arya. |
| 08:17 | Now, take a look at the URL. |
| 08:19 | It is localhost colon 8080 slash MyFirstProject slash GreetingServlet Path |
| 08:25 | Here we do not see the form data in the URL of the request. |
| 08:30 | This is the major difference between doGet and doPost methods. |
| 08:35 | Now, let us learn when to use GET and when to use POST methods. |
| 08:42 | GET method is used when: |
| 08:44 | * the form is small and hence the data is less. |
| 08:48 | * the user wants the contents of the data to be visible in the URL. |
| 08:53 | POST method is used when: |
| 08:55 | * the form is large and hence the data is more. |
| 09:00 | * the user does not want the contents of the data to be visible in the URL. |
| 09:06 | ex: passwords |
| 09:08 | Let us summarize. |
| 09:10 | In this tutorial we have learnt to: |
| 09:12 | * create a simple login form using JSP |
| 09:16 | * Pass parameters using doGet method |
| 09:19 | * Pass parameters using doPost method |
| 09:22 | * Difference between doGet and doPost methods. |
| 09:26 | Please make sure that you have completed this tutorial before proceeding further. |
| 09:32 | Watch the video available at the following link. |
| 09:35 | It summarizes the Spoken Tutorial Project. |
| 09:38 | If you do not have good bandwidth, you can download and watch it. |
| 09:42 | The Spoken Tutorial Project Team: |
| 09:45 | Conducts workshops using spoken tutorials. |
| 09:48 | Gives certificates for those who pass an online test. |
| 09:52 | For more details please write to: contact at spoken hyphen tutorial dot org. |
| 09:58 | Spoken Tutorial Project is a part of the "Talk to a Teacher" Project. |
| 10:02 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 10:09 | More information on this mission is available at http://spoken-tutorial.org/NMEICT-Intro |
| 10:19 | The Library Management System has been contributed by a leading software MNC through their "Corporate Social Responsibility Programme". |
| 10:28 | They have also validated the content for this spoken tutorial. |
| 10:32 | This is Arya Ratish from IIT Bombay, signing off. Thank you for joining. |
