Difference between revisions of "Java-Business-Application/C2/Database-and-validation/English-timed"
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| The first field is '''First Name '''of '''input type '''as''' text ''','''name '''as '''firstName '''and '''value '''as '''user '''''dot '''''getFirstName.''' | | The first field is '''First Name '''of '''input type '''as''' text ''','''name '''as '''firstName '''and '''value '''as '''user '''''dot '''''getFirstName.''' | ||
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Revision as of 15:21, 25 June 2014
| Time | Narration |
| 00:01 | Welcome to the spoken-tutorial on Database and validation. |
| 00:06 | In this tutorial we will learn to: |
| 00:08 | Interact with database |
| 00:10 | Validate the fields |
| 00:12 | Here we are using |
| 00:13 | Ubuntu Version 12.04 |
| 00:15 | Netbeans IDE 7.3 |
| 00:19 | JDK 1.7 |
| 00:21 | Firefox web-browser 21.0 |
| 00:24 | You can use any web-browser of your choice. |
| 00:28 | To follow this tutorial you must have knowledge of |
| 00:31 | Basics of Java Servlets and JSPs |
| 00:35 | Connecting to MySQL Database from Netbeans IDE |
| 00:39 | Creating database and tables |
| 00:42 | If not, for relevant tutorials please visit our website. |
| 00:47 | Now, let us go to Netbeans IDE. |
| 00:52 | I have started the MySQL server. |
| 00:55 | I have created a database in it named library. |
| 01:00 | I have created a table in it named Users. |
| 01:04 | I have already inserted some values into this table. |
| 01:08 | I will show them now. |
| 01:10 | For that, right click on Users and click on View Data. |
| 01:15 | Click on the Output button at the bottom. |
| 01:19 | We can see that there are 15 users here. |
| 01:23 | We can see the FirstName, Surname, Age, Gender, Email, Username and Password. |
| 01:31 | Now, let us load the JDBC driver that is Java Database Connectivity Driver. |
| 01:39 | For that, click on the Projects tab. |
| 01.42 | Right click on Libraries and Click on Add Library. |
| 01.46 | Then click on MySQL JDBC Driver. |
| 01.50 | And click on Add Library. |
| 01.53 | This will load the JDBC Driver. |
| 01.56 | Let us run the Project as we had done earlier. |
| 02.00 | Now, type the username as arya and password as arya123*. |
| 02.06 | Then click on Sign In. |
| 02.08 | We can see the successGreeting page. |
| 02.12 | Click on here to logout. |
| 02.15 | Now, let us switch back to the IDE. |
| 02.17 | We will go to GreetingServlet dot java. |
| 02.21 | Come to the doPost method |
| 02.23 | First, we get the Username and Password from the request using getParameter method. |
| 02.31 | Next we will see the code for JDBC connection. |
| 02.35 | We have initialized the Connection object, PreparedStatement object and Resultset object to null. |
| 02.44 | Then we register the driver in our program. |
| 02.48 | Then we create a connection to the database. |
| 02.52 | Then, we execute the prepareStatement method on the Connection object. |
| 02.58 | We give the query to get the user details from Users table. |
| 03.03 | We check if username and password is same as that which is entered in the form. |
| 03.09 | Here, the question mark denotes each field in the database. |
| 03.15 | To supply values in place of question mark, we execute the setString method. |
| 03.22 | We do this using the PreparedStatement object. |
| 03.26 | Then we execute the executeQuery method on the Prepared statement object |
| 03.33 | We store the result in ResultSet object |
| 03.37 | For successful login, we display the successGreeting page. |
| 03.43 | For this, we use the RequestDispatcher interface. |
| 03.48 | We use the getRequestDispatcher method on the request to obtain the RequestDispatcher object. |
| 03.56 | We then invoke the forward method on RequestDispatcher. object |
| 04.02 | In this way, we forward to successGreeting dot jsp. |
| 04.07 | Now switch back to the slides |
| 04.10 | Let us learn something about RequestDispatcher interface |
| 04.15 | This interface provides the facility of dispatching the request to another resouce |
| 04.22 | The resorce can be html, servlet, or jsp |
| 04.26 | Now let us come back to the IDE |
| 04.29 | Let us come to successGreeting dot jsp. |
| 04.33 | Here, we are displaying the success message You have successfully logged in. |
| 04:38 | Now, come back to the browser. |
| 04.41 | Type a username and password that we have not included in the database. |
| 04.47 | So, let me type abc as the username and abc123* as the password. |
| 04.56 | Then click on Sign In. |
| 04.59 | We can see that we get the error message on the same page itself. |
| 05.03 | Please correct the following error!!! Invalid username or password |
| 05.09 | Now, let us see the code for this. |
| 05.12 | So, Switch back to the IDE |
| 05.14 | Go to GreetingServlet dot java. |
| 05.17 | If the validation fails, then we should display the error messages. |
| 05.22 | First we have initialized a List of errorMsgs. |
| 05.27 | We set the variable errorMsgs into the request scope using setAttribute method. |
| 05.35 | Here, errorMsgs is the attribute name. |
| 05.39 | We have initialized a String variable id to null. |
| 05.44 | Then, we check if the user exists in the database. |
| 05.48 | If yes, we store the value in the variable id. |
| 05.53 | Else, we add the error Invalid username or password to errorMsgs list. |
| 06.00 | If the errorMsgs list is not empty, we display the error messages on index dot jsp.
|
| 06.09 | So, we have to redirect to index dot jsp.
|
| 06.13 | We have already seen how to redirect to another page using RequestDispatcher. |
| 06.20 | Note that we have included this code inside the try catch block to handle exception scenarios. |
| 06.27 | Now, we will see how to fetch errorMsgs variable in index dot jsp. |
| 06.34 | First, we obtain the value of the attribute errorMsgs. |
| 06.38 | This is done using getAttribute method on the request. |
| 06.44 | Note that we have included the Java code within the opening tag which is less than sign percentage sign and the closing tag percentage sign and greater than sign. |
| 06.57 | This block of code is known as scriptlet. |
| 07.02 | It contains Java code which is executed every time JSP is invoked. |
| 07.08 | If the value of errorMsgs is not null, then we display this message. |
| 07.15 | Please correct the following errors. |
| 07:18 | Then we iterate through list of errorMsgs. |
| 07.23 | We then display the error messages as a list. |
| 07.27 | This is how we display the error messages on index dot jsp. |
| 07.32 | Now, let us see how to add a user into the database. |
| 07.37 | Before adding a user into the database, we have to create a model for the User table. |
| 07.44 | Now, Let us see what a model is. |
| 07.48 | A model : |
| 07.49 | Represents the underlying, logical structure of data in a software application. |
| 07.55 | A Java class with attributes and setters and getters for them. |
| 08.00 | In this way, we can consider model as a whole instead of the individual attributes. |
| 08.07 | Now, Switch back to Netbeans IDE. |
| 08.11 | I have already created the model User dot java. |
| 08.16 | Note that we have created this Java class inside the package org dot spokentutorial dot model. |
| 08.24 | We have the following attributes firstName, surname, age, gender, email, username, password.
|
| 08.33 | We have initialized them to empty values. |
| 08.37 | Then we have a parameterized constructor. |
| 08.41 | We also have the default constructor. |
| 08.44 | We define the getFirstName method. |
| 08.47 | We also define the setFirstName method. |
| 08.51 | Similary we define the set and get methods on each of the attributes. |
| 08.57 | Come back to the browser. |
| 08.59 | Now, let us click on here link to register. |
| 09.03 | Type all the fields in the Registration Page. |
| 09.07 | Then click on Add User. |
| 09.10 | We get Add User Success Page. |
| 09.14 | We get the message Your request to add harshita was successful. |
| 09.20 | Here harshita was the username that we have given |
| 09.24 | Now, let us see how this is done. |
| 09.28 | So switch back to the IDE. |
| 09.30 | Go to AddUserServlet dot java. |
| 09.35 | The steps are similar to that we had followed in GreetingServlet dot java. |
| 09.40 | First we get the form parameters using the getParameter method. |
| 09.46 | We initialize variable user as instance of User Model with individual attributes. |
| 09.53 | We set the variable user into the request scope using setAttribute method. |
| 10.01 | If there are no errors while filling the form, we execute the query to insert the values into the user tables. |
| 10.10 | Then we forward to success user page |
| 10.15 | Now, let us come to successUser dot jsp. |
| 10.19 | First, we have imported User dot java. |
| 10.24 | This line of code is called directive in JSP. |
| 10.28 | A JSP directive starts with opening tag less than sign percentage sign and at the rate sign and ends with closing tag percentage sign and greater than sign. |
| 10.42 | This one is a page directive. |
| 10.45 | The page directive contains a list of all imported packages. |
| 10.50 | We get the value of the attribute user and store it as the User object. |
| 10.57 | Then,We have the success message here. |
| 11.00 | Here, we have retrieved the Username. |
| 11.04 | We have used the getUsername() method on the request object. |
| 11.09 | We have done this using scriptlet tags. |
| 11.12 | Now, let us come back to the browser. |
| 11.15 | We will try to add a user already present in the database. |
| 11.20 | So, I will add harshita again. |
| 11.24 | We can see that we get the error message Please correct the following errors!!1 Duplicate entry 'harshita' for key username. |
| 11.33 | Now, Let us register for a user once again. |
| 11.37 | Here, I have filled up the form now. |
| 11.40 | I have created a mistake in the Age field. |
| 11.44 | I have typed ab instead of a valid number. |
| 11.48 | Now, click on Add User. |
| 11.51 | We see we get the error message The age must be a positive integer. |
| 11.57 | Now, let us see how this is done.
|
| 12.00 | Switch back to the IDE. |
| 12.03 | Open AddUserServlet dot java. |
| 12.08 | Here also, we have created a list for errorMsgs. |
| 12.11 | Then we set the variable errorMsgs into the request scope using setAttribute method. |
| 12.18 | Then, we have declared ageUser of type integer and we have initialize it to -1 |
| 12.26 | Inside the try catch block we have used parseInt method. |
| 12.31 | This will return an integer, given a string representation of number as input. |
| 12.37 | So here we validate that the age field contains a valid positive integer. |
| 12.44 | If the validation fails, then we add error message to errorMsgs list |
| 12.51 | The age must be a positive integer. |
| 12.54 | Similarly, we have to validate that all the other fields too have valid data. |
| 13.01 | If the errorMsgs list is not empty, then we will display the errorMsgs on addUser dot jsp itself |
| 13.09 | We have already seen how to do this using the RequestDispatcher. |
| 13.15 | Now, let us come to the addUser dot jsp. |
| 13.19 | Here also, first we have imported User dot java. |
| 13.24 | Inside the scriptlet tags we have created an object of type User. |
| 13.31 | Then we get the value of the attribute errorMsgs using getAttribute method. |
| 13.38 | We check if this value is equal to null. |
| 13.43 | If it is not equal to null, then we display the error message just as we had done for index dot jsp. |
| 13.51 | If not, we will get the value of the attribute user from request using User model. |
| 13.59 | Then we have the form. |
| 14.01 | The form tag has action as AddUserServlet and method as POST. |
| 14.07 | The first field is First Name of input type as text ,name as firstName and value as user dot getFirstName. |
| 14.18 | Here, we are initializing the value of firstName to empty string. |
| 14.24 | Similarly you have to do for other fields. |
| 14.28 | We also have a submit button and value as Add User.
|
| 14.33 | This is how we validate the fields in addUser.jsp. |
| 14.38 | You can try out different errors on the Add User page. |
| 14.42 | Now let us see that the user harshita has been added to the database. |
| 14.49 | So come back to user table. We can see that harshita is added to the database. |
| 14.56 | In this tutorial we have learnt: |
| 14.58 | Database connectivity and |
| 15.00 | Field validation |
| 15.02 | To know more about the spoken tutorial project, watch the video available at the following link. |
| 15.07 | It summarizes the Spoken Tutorial Project |
| 15.11 | If you do not have good bandwidth you can download and watch it |
| 15.15 | The Spoken Tutorial Project Team |
| 15.17 | Conducts workshops using spoken tutorials |
| 15.20 | Gives certificates for those who pass an online test |
| 15.23 | For more details please write to contact at spoken hyphen tutorial dot org |
| 15.29 | Spoken Tutorial Project is a part of the Talk to a Teacher Project |
| 15.32 | It is supported by the National Mission on Education through ICT, MHRD, Government of India |
| 15.38 | More information on this mission is available at spoken-tutorial.org/NMEICT-intro |
| 15.48 | The Library Management System has been contributed by a leading software MNC, through their Corporate Social Responsibility Programme. |
| 15.57 | They have also validated the content for this spoken tutorial. |
| 16.02 | This is Arya Ratish from IIT Bombay signing off.
|
Contributors and Content Editors
Nancyvarkey, PoojaMoolya, Pratik kamble, Sandhya.np14, Shruti arya
