Difference between revisions of "Java-Business-Application/C2/Database-and-validation/English-timed"
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| 00:06 | | 00:06 | ||
− | | In this tutorial we will learn to: | + | | In this tutorial, we will learn to: |
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| 00:08 | | 00:08 | ||
− | | '''Interact with database''' | + | |* '''Interact with database''' |
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| 00:10 | | 00:10 | ||
− | | '''Validate the fields''' | + | |* '''Validate the fields'''. |
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| 00:12 | | 00:12 | ||
− | |Here we are using | + | |Here we are using: |
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| 00:13 | | 00:13 | ||
− | | '''Ubuntu Version''' 12.04 | + | |* '''Ubuntu Version''' 12.04 |
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| 00:15 | | 00:15 | ||
− | | '''Netbeans IDE''' 7.3 | + | |* '''Netbeans IDE''' 7.3 |
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| 00:19 | | 00:19 | ||
− | | '''JDK''' 1.7 | + | |* '''JDK''' 1.7 |
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| 00:21 | | 00:21 | ||
− | | '''Firefox''' web-browser 21.0 | + | |* '''Firefox''' web-browser 21.0 |
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| 00:28 | | 00:28 | ||
− | |To follow this tutorial you must have knowledge of | + | |To follow this tutorial, you must have knowledge of |
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| 00:31 | | 00:31 | ||
− | | Basics of '''Java Servlets''' and '''JSPs''' | + | |* Basics of '''Java Servlets''' and '''JSPs''' |
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| 00:35 | | 00:35 | ||
− | | Connecting to '''MySQL Database ''' from '''Netbeans IDE''' | + | |* Connecting to '''MySQL Database ''' from '''Netbeans IDE''' |
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| 00:39 | | 00:39 | ||
− | | Creating '''database '''and '''tables''' | + | |* Creating '''database '''and '''tables''' |
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| 01:42 | | 01:42 | ||
− | | Right click on '''Libraries''' and | + | | Right click on '''Libraries''' and click on '''Add Library.''' |
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| 02:17 | | 02:17 | ||
− | | We will go to '''GreetingServlet | + | | We will go to '''GreetingServlet '''dot '''java.''' |
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| 02:21 | | 02:21 | ||
− | | Come to the '''doPost''' method | + | | Come to the '''doPost''' method. |
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| 03:03 | | 03:03 | ||
− | | We check if '''username '''and '''password '''is same as that which is entered in the form. | + | | We check if '''username '''and '''password '''is same as that which is entered in the '''form'''. |
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| 03:26 | | 03:26 | ||
− | | Then we execute the '''executeQuery method '''on the '''Prepared statement''' object | + | | Then we execute the '''executeQuery method '''on the '''Prepared statement''' object. |
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|03:33 | |03:33 | ||
− | |We store the result in '''ResultSet''' object | + | |We store the result in '''ResultSet''' object. |
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| 03:56 | | 03:56 | ||
− | | We then invoke the '''forward method '''on '''RequestDispatcher.''' object | + | | We then invoke the '''forward method '''on '''RequestDispatcher.''' object. |
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| 04:02 | | 04:02 | ||
− | | In this way, we '''forward '''to '''successGreeting | + | | In this way, we '''forward '''to '''successGreeting '''dot '''jsp.''' |
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| 04:07 | | 04:07 | ||
− | |Now switch back to the slides | + | |Now switch back to the slides. |
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| 04:10 | | 04:10 | ||
− | |Let us learn something about '''RequestDispatcher interface''' | + | |Let us learn something about '''RequestDispatcher interface'''. |
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| 04:15 | | 04:15 | ||
− | | This interface provides the facility of dispatching the '''request''' to another | + | | This interface provides the facility of dispatching the '''request''' to another resource. |
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| 04:22 | | 04:22 | ||
− | | The | + | | The resource can be html, servlet, or jsp. |
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| 04:26 | | 04:26 | ||
− | | Now let us come back to the IDE | + | | Now let us come back to the IDE. |
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| 04:29 | | 04:29 | ||
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| 04:59 | | 04:59 | ||
− | | We can see that we get the '''error message '''on the same page itself. | + | | We can see that we get the '''error message '''on the same '''page''' itself. |
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| 05:03 | | 05:03 | ||
− | | '''Please correct the following error!!! Invalid username or password''' | + | | '''Please correct the following error!!! Invalid username or password'''. |
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| 05:12 | | 05:12 | ||
− | | So, Switch back to the '''IDE''' | + | | So, Switch back to the '''IDE'''. |
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| 05:14 | | 05:14 | ||
− | | Go to '''GreetingServlet | + | | Go to '''GreetingServlet '''dot '''java.''' |
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| 05:17 | | 05:17 | ||
− | | If the '''validation '''fails | + | | If the '''validation '''fails then we should display the '''error message.''' |
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| 06:00 | | 06:00 | ||
− | | If the '''errorMsgs list '''is not empty, we display the '''error messages '''on '''index | + | | If the '''errorMsgs list '''is not empty, we display the '''error messages '''on '''index '''dot '''jsp.''' |
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| 06:09 | | 06:09 | ||
− | | So, we have to redirect to '''index | + | | So, we have to redirect to '''index ''' dot '''jsp.''' |
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| 06:13 | | 06:13 | ||
− | | We have already seen how to redirect to another page using '''RequestDispatcher.''' | + | | We have already seen how to redirect to another '''page''' using '''RequestDispatcher.''' |
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| 06:27 | | 06:27 | ||
− | | Now, we will see how to fetch '''errorMsgs '''variable in '''index | + | | Now, we will see how to fetch '''errorMsgs '''variable in '''index '''dot '''jsp.''' |
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| 06:44 | | 06:44 | ||
− | | Note that we have included the '''Java code '''within the opening tag which is ''less than sign percentage sign ''and the | + | | 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.'' |
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| 07:08 | | 07:08 | ||
− | | If the value of '''errorMsgs '''is not null | + | | If the value of '''errorMsgs '''is not null then we display this message. |
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| 07:27 | | 07:27 | ||
− | | This is how we display the '''error messages''' on '''index | + | | This is how we display the '''error messages''' on '''index dot jsp.''' |
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| 08:07 | | 08:07 | ||
− | | Now, | + | | Now, switch back to '''Netbeans IDE.''' |
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| 08:16 | | 08:16 | ||
− | | Note that we have created this '''Java class '''inside the '''package org | + | | Note that we have created this '''Java class '''inside the '''package org dot spokentutorial dot model.''' |
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| 08:51 | | 08:51 | ||
− | | | + | | Similarly we define the '''set '''and '''get methods '''on each of the '''attributes.''' |
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| 09:14 | | 09:14 | ||
− | | We get the message ''' Your request to add harshita was successful.''' | + | | We get the message: ''' Your request to add harshita was successful.''' |
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| 09:20 | | 09:20 | ||
− | | Here '''harshita''' was the '''username''' that we have given | + | | Here '''harshita''' was the '''username''' that we have given. |
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| 09:35 | | 09:35 | ||
− | | The steps are similar to that we had followed in '''GreetingServlet | + | | The steps are similar to that we had followed in '''GreetingServlet '''dot '''java.''' |
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|10:19 | |10:19 | ||
− | | First, we have imported '''User | + | | First, we have imported '''User '''dot '''java.''' |
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| 10:28 | | 10:28 | ||
− | | A '''JSP directive''' starts with | + | | 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'. |
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Revision as of 08:56, 14 June 2015
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 Projectas we had done earlier. |
02:00 | Now, type the username as arya and password as arya*123. |
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 resource. |
04:22 | The resource 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 message. |
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 | Similarly 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 try to 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.
Thank you for joining. |
Contributors and Content Editors
Nancyvarkey, PoojaMoolya, Pratik kamble, Sandhya.np14, Shruti arya