JSP Custom Tag Empty Custom Tag

JSP- Custom Tag- Empty Tag.

Introduction:

                        Empty custom tag means that does not have any attributes or body.

< mytag:hello/ >

Creating Custom Tag-Empty Tag:

To create custom tag, three components need.

Ø      The tag library descriptor file that maps the XML elements to the tag implementation.

Ø      The tag handler class that defines tags behavior.

Ø      The JSP file that uses the tag library

                

Procedure:

Step 1:

                       Create Project named as CustomTagProject.

                 

Note:Already we have seen how to create the project for developing the web application.

Step 2:

Create two Folders. One for storing jsp files. Another one for storing   Tag Handler class.

Note: Already we have seen how to create Folder in the previous post. Also we have seen where to create Folder for storing jsp file and where to create Folder for storing tag handler class.

Structure of the CustomTagProject

You can save jsp file under jsp folder. And also you can save the tag handler class under javaclass Folder.

Task 1:Tag Library Descriptor file (TLD file)

First task is to identify the java class for the server and to associate it with a particular XML tag name. Let us create TLD file.

Let us see how to create TLD files.

We give TLD file name as myown-taglib.tld

Step1:

Right click on WEB-INF and select New and Other

New File window will open.

Select web under Categories

Also select Tag Library Descriptor(TLD) under File Types

 

Next

New Tag Library Descriptor window will open.

You give TLD name as welcome.tld

Also give prefix name as wel

After creaing welcome.tld. you can see welcome.tld file like below.

welcome.tld


< ?xml version="1.0" encoding="UTF-8"? >
< taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd >
< tlib-version > 1.0 < /tlib-version >
< short-name > wel < /short-name >
< uri > /WEB-INF/tlds/welcome < /uri >

< /taglib >

Task 2:Tag Handler Class

Ø      The second task is to define a java class that tells the JSP ENGINE what to do when it sees the tag.

Ø      This class must implements javax.servlet.jsp.tagext.Tag interface.

Ø      Extends TagSupport or BodyTagSupport

Let us go to create java class that display “welcome India”

Right click on javaclass. And select New and Other.

New File window will open.

Where you select web under categories

And also select Tag Handler under File types

Next

New Tag Handler window will open.

You give Tag Handler name as Welcome.

Next

New File window will open.

Where you select TLD

Browse and select TLD under WEB-INF\tlds\welcome.tld

Select Body Content: empty

Finish

Welcome.java file is successfully created.

Welcome.java

package javaclass;

import javax.servlet.jsp.JspWriter;

import javax.servlet.jsp.JspException;

import javax.servlet.jsp.tagext.JspFragment;

import javax.servlet.jsp.tagext.SimpleTagSupport;

import javax.servlet.jsp.tagext.TagSupport;

public class Welcome extends TagSupport

{

    public int doStartTag() throws JspException

    {

        try

        {

            JspWriter out=pageContext.getOut();

            out.println("Welcome India");

        }

        catch(Exception e)

        {

        }

        return SKIP_BODY;

    }

    public int doEndTag() throws JspException

    {

        return SKIP_PAGE;

    }

}

Create JSP file

Create jsp file  -- Home.jsp

Let us see how to create Home.jsp

Right click on jsp Folder.

New File window will open.

Where you select web under categories and select JSP under File Types.

Next

New JSP File window will open.

Finish

Home.jsp file is successfully created.

In Home.jsp, we include taglib directive.

How to include Taglib directive.

< %@taglib uri="/WEB-INF/tlds/welcome" prefix="wel" % >

We create jsp file. We define taglib tag to include custom tag into jsp.


Include following jsp coding into the Home.jsp

< %@taglib uri="/WEB-INF/tlds/welcome" prefix="wel" % >
< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >

< html >
< head >
< title > JSP Home Page < /title >
< /head >
< body >
< h1 > Hello World! < /h1 >
< wel:Welcome/ >
< /body >
< /html >


Run the Home.jsp

Right click on Home.jsp and select Run File.

You get output

Strutcture Of The CustomTagProject

JSP Custom Tag

JSP-Custom Tag

Introduction:

                        Custom tag is user-defined tag that enables us to minimize complex and repetitive business logic in jsp by creating the reusable components, which can be used in another application.

package:

                        javax.servlet.jsp.tagext;

Custom tag API:

Custom tag API consists of classes and interfaces of the javax.servlet.jsp.tagext that are used to create custom tag.

Interfaces:

1). Tag

2). IterationTag

3). BodyTag

Classes:

1). BodyContent

2). TagSupport

3). BodyTagSupport

4). TagData

5). TagInfo

6). TagLibraryInfo

7). TagVariableInfo         

Tag Interface

Tag Interface has many methods.

1). doStartTag()

2). doEndTag()

3). release()

4). setPageContext()

5). setParent()

6). getParent()

                                                            IterationTag

The IterationTag interface extends Tag Interface.

                           doAfterBody()

                           

                            Re-evaluation of the body content of custom tag

 

                                                           BodyTag

The BodyTag interface  extends IterationTag

This interface defines method that enable ag handler to manipulate the body content of custom tag.

1). doInitBody

2). setBodyContent()

Type of custom tag

1). Custom Tag- Empty Tag

2). Custom Tag- tag with Attributes

3). Custom Tag- tag with body

4). Custom Tag- nested Tags

JSP Login Example

JSP Login Example

Problem:

            Get input such as username and password from user.

            Check given username as sureshkumar and password as murugan.

Solution:

            Step 1:

                        Create jsp page(Home.jsp)

                        Get username and password from user.

Home.jsp

 

 

< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >

< html >
< head >
< title > JSP Home < /title >
< /head >
< body >
< h1 > Login Example < /h1 >
< form method="post" action=http://localhost:8084/DataBasePro/jsp/validate.jsp >
< table >
< tr >

< td > UserName < /td >
< td > < input type="text" name="uname" > < /td >

< /tr >

< tr >
< td > Password < /td >
< td > < input type="password" name="pwd" > < /td >
< /tr >

< tr >
< td > < input type="submit" value="Login" > < /td >
< td > < input type="reset" value="Clear" > < /td >
< /tr >
< /table >
< /form >
< /body >
< /html >


validate.jsp

< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >

< html >
< head >
< title > JSP Validate Page < /title >
< /head >
< body >
< h1 > Login Example < /h1 >

< %
String username=request.getParameter("uname");
String password=request.getParameter("pwd");

if(username.equals("sureshkumar")&&(password.equals("murugan")))
{
out.println("You Are Valid User");
}
else
{
out.println("You Are Not Valid User");
}
% >
< /body >
< /html >

Explain:

            Using Home.jsp, we will get username and password.

Using validate.jsp, we will check the given username as sureshkumar and password as murugan. If it is true, the You Are Valid User message will display.

Otherwise, the You Are Not Valid User message will display.

Note: you give username as suresh , you will get message You Are Not Valid User.

JSP delete query using JDBC

JSP- Delete Query using JDBC

Aim:

            Using JDBC, we will delete the record from mysql database.

Problem:

            Already we insert many records in exam table.

            Now we have to delete suresh records.

Procedure:

Step 1:

            Load the Driver

            Class.forName(“com.mysql.jdbc.Driver”);

Step 2:

            Create Connection

            String driver=”jdbc:mysql://localhost/example”;

            Connection con=DriverManager.getConnection(driver,”username”,”password”);

Step 3:

            Create Statement

            Statement stmt=con.createStatement();

Step 4:

            Execute Query

            String sql=”delete from exam where student_name=’suresh’ “;

            stmt.executeUpdate(sql);

Step 5:

            Create jsp file

            I have given jsp file name as DeleteExample.

            Add following coding into DeleteExample.

< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >
< %@page import="java.sql.*" % >
< html >
< head >
                     < title > Java DataBase Connectivity Example-Delete Query < /title >
< /head >
< body >
< %!
                     Connection con=null;
                      ResultSet rs=null;
                     Statement stmt=null;
% >
<%
try
{
                       Class.forName("com.mysql.jdbc.Driver");
}
catch(Exception e)
{
                        out.println(e.getMessage());
}
try
{
         con=DriverManager.getConnection("jdbc:mysql://localhost/example","root","sure");
         stmt=con.createStatement();
         int i=stmt.executeUpdate("delete from exam where student_name='suresh'");
         if(i==1)
         {
                out.println("Successfully Deleted");
          }
          else
          {
                  out.println("Error For Inserted");
           }
}

catch(Exception e)
{
               out.println(e.getMessage());
}
finally
{
         con.close();
         stmt.close();
}
% >
< /body >
< /html >


Step 6:

Include mysql-connector.jar

Already we have included mysql-connector.jar into our project. So no need to include again.

Step 7:

Run the Application

Already I have explained how to run the application.

Step 8:

Get the output

JSP update query using JDBC

JSP- update statement

Introduction:

Sometimes we want to change the inserted data into the database.
If you want to update the student_name in our exam table, you’ll use a SQL statement like the one below:

mysql > update exam set student_name=’suresh’ where student_name=’sureshkumar’;


Problem:

Update data in mysql database.

We have to change student_name as kannanto kamalkannan.

Procedure:

Already How to import mysql-connector.jar and how to create database and how to create table and how to insert data into the table and how to select the inserted data in exam table.

Step 1:

Use update SQL statement to update data in our exam table.

We use update SQL statement to update data in mysql

Step 2:

Create jsp file I have used file name as updatePro.

Include following coding into updatePro

< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >
< %@page import="java.sql.*" % >
< html >
< head >
< title > Java DataBase Connectivity Example-Update Query < /title >
< /head >
< body >
< %!
Connection con=null;
ResultSet rs=null;
Statement stmt=null;
% >
< %
try
{
Class.forName("com.mysql.jdbc.Driver");
}
catch(Exception e)
{
out.println(e.getMessage());
}
try
{
con=DriverManager.getConnection("jdbc:mysql://localhost/example","root","sure");
stmt=con.createStatement();
int i=stmt.executeUpdate("update exam set student_name='kamalkannan' where student_name='kannan'");
if(i==1)
{
out.println("Successfully Updated");
}
else
{
out.println("Error For Updated");
}
}

catch(Exception e)
{
out.println(e.getMessage());
}
finally
{
con.close();
stmt.close();
}
% >
< /body >
< /html >

Step 3:

Step 4:

            We want to check the data is updated successfully.

JSP select query using JDBC

JSP- Select Query.

Problem:

              Using Select Query, to retrieve the data from table using jsp and mysql.

             We follow some steps to connect jsp with mysql database.

1). Load the Driver

            Class.forName(“com.mysql.jdbc.Driver”);

            This statement load the mysql Driver.

2). Create the Connection

 String s=”jdbc:mysql://localhost/Database_Name”,”username”,”password”

           

Connection con=DriverManager.getConnection(s);

3). Create Statement

            Statement stmt=con.createStatement();

            String sql=”select * from Table_Name”;

            Stmt.executeQuery(sql);

Requirements:

            Netbean 6.8

            Mysql 6.0

            Knowledge from mysql.

Procedure:

             Step 1:

                        Create DataBase named as example.

            How to Create Database

 

Mysql > create database example;

Successfully database is created.

Step 2:

Use database.

How to activate example database?

Mysql > use example;

Step 3:

create table named exam.

Mysql > create table exam(student_name varchar(40),rollno varchar(20));

Step 4:

Insert data into exam table in example database.

Mysql > insert into exam values(‘anbuselvan’,’2k2ccs2006’);

Step 5:

Create jsp file using netbean IDE.

Give any file name for jsp. I have given jsp file name as databaseExam.jsp

Already I have explained How to create jsp file using netbean 6.8. if you forget the procedure. Please remind the previous post and you will continue this post.

Next

Include following coding into databaseExam.jsp

< %@page contentType="text/html" pageEncoding="UTF-8"% >
< !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
http://www.w3.org/TR/html4/loose.dtd >
< %@page import="java.sql.*" % >
< html >
< head >
                   < title > Java DataBase Connectivity Example For Select < /title >
< /head >
< body >
< %!
             Connection con=null;
             ResultSet rs=null;
             Statement stmt=null;
% >
< %
try
{
               Class.forName("com.mysql.jdbc.Driver");
}
catch(Exception e)
{
              out.println(e.getMessage());
}
try
{
             con=DriverManager.getConnection("jdbc:mysql://localhost/example","root","sure");
             stmt=con.createStatement();
             rs=stmt.executeQuery("select * from exam");

           while(rs.next())
           {

                 out.println(rs.getString(1));
                out.println(rs.getString(2)) ;
          }

}
catch(Exception e)
{
               out.println(e.getMessage());
}
% >
< /body >
< /html >

You will run the databaseExam.jsp

Step 4:

Note:
          Already I have explained how to include mysql-connector.jar in our project. 


          Run the Application

You will get the output